Source: KANSAS STATE UNIV submitted to NRP
REGULATION OF PHOTOSYNTHETIC PROCESSES
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1000042
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
NC-_old1200
Project Start Date
May 29, 2013
Project End Date
Sep 30, 2017
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
KANSAS STATE UNIV
(N/A)
MANHATTAN,KS 66506
Performing Department
KSU NW Agriculture Research Center
Non Technical Summary
Photosynthesis provides the basis for plant growth; supports production of food, animal feed, fiber, bio-energy products and sustains the natural environment. Environmental factors such as drought, chilling and excessive heat can damage or impair photosynthetic processes. Our research goal is to increase knowledge of the response of photosynthesis to environmental factors (excessive heat, cold, and drought as well as use of nitrogen and water) that limit plant productivity. Our studies will be conducted under field and controlled environment conditions, with emphasis on whole-plant responses. We will use standard techniques such as canopy temperature measurements, gas exchange instrumentation, leaf fluorescence, pollen viability, seed-set percentage, and harvest index to quantify effects of heat stress, and develop remote sensing methods for assessing stress responses in the field. We will apply these techniques to evaluate genotypes of sorghum, wheat and soybean to identify tolerance to drought or heat stress. For example, to assess drought stress, canopy conductance will be inferred from digital images which provide information about leaf photosynthetic activity. As a consequence, new methods of evaluating plant performance, under stress conditions (including remote sensing) will become available and will lead to a refinement of our understanding of the impacts of these stresses on plant growth. Genes or metabolic pathways associated with water- and nitrogen-use efficiency and tolerance to temperature extremes and drought will be identified in wheat, soybean and sorghum. New stress tolerant crop hybrids and varieties, including those with greater nitrogen- and water-use efficiency, will be developed by manipulating the genes or pathways associated with environmental limitations to photosynthesis. The major advances and discoveries of this research will be published in scientific journals and meeting proceedings.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
20616201060100%
Knowledge Area
206 - Basic Plant Biology;

Subject Of Investigation
1620 - Warm season perennial grasses;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
Analyze the limitations to photosynthetic productivity caused by environmental factors.
Project Methods
Research studies will focus on abiotic stress physiology and germplasm screening. Field and controlled-environment studies will be conducted to evaluate genotypes of sorghum, wheat and soybean for tolerance to drought or heat stress. Stomatal behavior is central to both drought stress and water use efficiency, and will be actively investigated. These studies will apply theoretical consideration to simulate stomatal behavior based on radiation utilization and to develop canopy temperature and chlorophyll fluorescence as drought screening tools. Studies will investigate the effects of high temperature stress on photosynthesis and fruit-set with emphasis on the inhibitory effects which may be mediated through ethylene response through production of reactive oxygen species and subsequent membranes damage. Efforts will include phenotyping studies to elucidate the basis of the slow wilting trait in sorghum and to examine the response of to vapor pressure deficit. These studies will utilize physiological techniques such as canopy temperature measurements, gas exchange instrumentation, leaf fluorescence, pollen viability, seed-set percentage, and harvest index to quantify effects of abiotic stresses. Field studies will also develop and utilize remote sensing techniques (visible, near infrared and thermal ranges), in-canopy measure of light transmittance, gas exchange instrumentation and leaf fluorescence techniques to quantify assimilation responses to radiation and to simulate stomatal behavior. These studies will investigate the role of canopy architecture as a component of assimilation responses to abiotic stress, complementing the role of stomatal regulation. Techniques under development will support large through-put characterization of phenotypic expression, required in studies of gene expression as well as classical crop breeding. The major advances and discoveries of this research will be published in scientific journals and meeting proceedings. Peer-reviewed publication is the best practical method for evaluating the quality and impact of the research results. Research results will also be presented as platform lectures and poster presentations at local, regional, national, and international scientific meetings.

Progress 05/29/13 to 09/30/17

Outputs
Target Audience:Crop scientists, crop advisors, public agency representatives and the farming public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Seven graduate students (S. Narayanan, G. Pradhan, A. Ehtaiwesh, K Shroyer, K. Pidaran, A. Chiluwal, N. Jayram) and four postdoctoral research associate (M. Djanaguiraman, A. Araya, D. Sebela and J. Sunoj) contributed to project objectives. Investigators pursued professional development by participating in conferences, symposia and workshops noted above. How have the results been disseminated to communities of interest?Experimental results were presented to scientific groups at American Society of Agronomy annual meetings at Tampa FL (11/4-6/2013), Long Beach, CA (11/2-5/2014), Minneapolis, MN (11/16/2015), and Phoenix, AZ (11/6-9/2016); CIMMYT Workshop "Modeling Wheat Response to High Temperature", 6/19-21/2013, El Batan, Mexico; "Tear-Down-the-Walls" High Plains Regional Agronomists meeting, Colby, KS (8/14-15/2013); NC1200 Annual Meetings in Lincoln, NE (11/23/2013), Kansas City, MO (11/14/2014), St. Louis, MO (11/7/2015), Missoula, MT (10/ /2016); K-State Center for Sorghum Improvement (7/7/2014), and Plant and Animal Genome Conference, San Diego, CA (1/9-13/2016). Experimental results were presented to producer organizations including National Sunflower Association Research Forum at Fargo, ND (1/7/2013); NWREC Field Day, Colby, KS (6/4/2013 and 9/4/2014); SWREC Field Day, Garden City, KS (8/29/2013) and the Sorghum Improvement Congress of North America at Lubbock, TX (8/27/2013), Manhattan, KS (9/2/2015), and Manhattan, KS (9/19-21/2016). In addition, research results have been highlighted in professional publications (Short-statured sunflower: 'Sunflower' magazine 2012; Wheat water productivity manuscript featured in Certified Crop Advisor profile https://www.certifiedcropadviser.org/ and Advances in Engineering profile http://advanceseng.com/general-engineering/; Sorghum radiation and water use manuscript featured in CSA news (June, 2013). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? High-temperature stress in wheat significantly decreased chlorophyll content, damaged thylakoid membrane, and decreased photosynthesis and grain yield. There was genetic variability for high temperature tolerance. New potential sources of heat-tolerant genotypes in wheat included wild relatives of wheat, chromosomal substitution lines and synthetic wheat collections. Germplasm collections were screened for root traits that may play significant roles in drought tolerance and yield improvement. Heat stress increased reactive oxygen species concentration and membrane damage in wheat and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. These results suggest that high night-time and daytime temperatures during flowering cause damage of a similar magnitude to winter wheat. We measured 165 glycerolipids and sterol derivatives under optimum and high day and night temperatures in wheat pollen. Levels of polar lipid fatty acyl chain unsaturation were lower under high temperatures, compared to optimum temperature. Levels of 18:3-containing triacylglycerols increased 3-fold/more under high temperatures, consistent with their possible role in sequestering fatty acids during membrane lipid remodeling. Correlation analysis of lipid levels revealed 13 groups of co-occurring lipids, which are up-or down-regulated together through time during high temperature stress; likely because they are regulated by the same enzyme(s). The data demonstrate that wheat leaf lipid composition is altered by high day and night temperature stress, that some lipids are particularly responsive to high temperatures, and co-occurring lipids represent groups that can be explained by coordinated metabolism. Wheat breeding lines differed in grain carbon isotope discrimination (CID) an indicator of water stress avoidance which was positively correlated with grain yield. These results indicate that grain CID could be a useful selection criterion for grain yield improvement under moderate drought stress, especially post-anthesis drought, in temperate semi-arid regions. Analysis of grain yield formation factors for winter wheat indicated that yield was determined by the product of kernel frequency and kernel mass--with dominant influence of environmental conditions. Genetic factors affected spike frequency and kernels per spike, which exhibited compensatory growth patterns. CID, an indicator of stress avoidance, indirectly contributed to yield via effects of biomass accumulation. Wheat grown in water-deficient intensive cropping systems had less biomass productivity relative to crop water use. This finding contrasted with evidence of greater transpiration efficiency for wheat in intensive systems, indicated by smaller grain CID. The reduced water productivity at the cropping system level was attributed to a smaller transpiration fraction of crop water use for wheat in the more intensive cropping systems. Sorghum genotypes differed for percentage seed-set under high temperature (HT) stress. Genotypes with high maximum temperature and pollen germination had improved percentage of seed-set under HT stress. This research suggest that HT stress tolerant genotypes can be identified by quantifying oxidative damage in pollen grains and by measuring pollen germination, seed-set percentage and grain yield at HT. Heat stress had greatest effects, decreasing floret fertility in sorghum, when imposed between 10 and 5 d before flowering; and between 5 d before- and 5 d after-flowering. Mean daily temperatures >25°C decreased floret fertility (reaching 0% at 37°C) when imposed at the start of panicle emergence. Temperatures ranging from 25 to 37°C decreased individual grain weight when imposed at the start of grain filling. In sorghum water use efficiency (WUE) was more strongly correlated with biomass production than to water use. These results imply that it is possible to improve WUE without compromising biomass production. A limited-transpiration (TRlim) trait, found in sorghum, results in restricted transpiration rate under high vapor pressure deficits (VPD). The benefit of TRlim is that under high midday-VPD conditions crop water loss is limited so that there is water conservation enabling the crop to better withstand later-season drought. Only three of 16 genotypes expressing TRlim at 31 °C sustained expression of TRlim at 37°C. In conditions in which very high temperatures threaten crop heat stress, those genotypes that lose the TRlim trait at high temperature may be more desirable since increasing transpiration rates at these temperatures can result in leaf cooling. Evaluation of leaf hydraulic conductance indicated that low hydraulic conductance in sorghum line SC15 was associated with conservative water use by restricting transpiration at higher soil water content during soil drying and under high VPD (above 2.1 kPa). Tests with inhibitors indicate that these differences may be linked to differences between their aquaporin populations. We partitioned leaf hydraulic resistance of six genotypes of Sorghum bicolor L. (Moench) into leaf specific hydraulic resistance within the large longitudinal veins and outside the large veins. The hydraulic resistance of leaf tissue limits the maximum rate of transpiration and photosynthesis. As the soil dries, maintenance of cell turgor and function was affected by the ability of leaf veins to move water long distances. Genotypes with increased hydraulic resistance through the leaf had less evapotranspiration resulting in more conservative water use. These results illustrate that leaf resistance characteristics can alter water use and plant responses to declining soil moisture. Genetic mapping studies were conducted with grain sorghum, seeking genetic links to physiological traits including grain yield, flowering time, chlorophyll content, chlorophyll fluorescence and duration of green leaves. Complementary methods revealed fifteen genetic links to the traits studied. A genetic link for grain yield under normal and stressed conditions was identified in chromosome 1. Genetic links for flowering time were found in chromosomes 2, 6 and 9. Green leaf duration was linked to genes in chromosomes 3 and 4. A separate study identified a genetic link (Locus 7-2) to germination of sorghum seeds under cold conditions (12 °C). These identified genetic linkages could be used to improve grain yield, flowering time and green leaf duration in sorghum molecular breeding programs. High day- or night-time temperatures increased leaf respiration and decreased photochemical quenching, electron transport rate and leaf photosynthesis, and pollen germination in soybean. Overall, high temperatures during flowering decreased leaf photosynthesis and pollen germination, leading to decreased pod-set percentage and seed weight. Soybean genotypes, released from the 1920s through 2010, were evaluated for productivity and physiological characteristics. Among genotypes, seed yield and chlorophyll content increased with year of release. Canopy temperature decreased with year of release. Selecting for these traits in plant breeding programs may improve genetic gain. In corn (hybrid DKC47-27RIB) lower diurnal temperature amplitude led to a linear increase in night respiration and a linear decrease in total sugars, non-reducing sugars, starch concentrations, plant height, total leaf area and total biomass accumulation. The results imply that narrowing diurnal temperature amplitude as a result of higher night temperature is the major driver of the negative impact on vegetative growth in maize. Simulation work, using the Kansas Water Budget model, indicated that crop water production functions, which are embedded in the model, can be effectively used to quantify effects of limited water supply on grain productivity of winter wheat and grain sorghum.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Prasad P. V. Vara, B R, Raju, Jagadish SVK. 2016. Field crops and the fear of heat stressOpportunities, challenges and future directions. Field Crops Research. 200. 114-121. 10.1016/j.fcr.2016.09.024.
  • Type: Journal Articles Status: Published Year Published: 2017 Citation: Yang, H.S., P. Grassini, K.G. Cassman, R.M. Aiken and P.I. Coyne. 2017. Improvements to the Hybrid-Maize model for simulating maize yields in harsh rainfed environments. Field Crops Research 204:180-190. Sunoj, J., I. Somayanda, A. Chiluwal, R. Perumal, P.V.V. Prasad, S.V.K Jagadish. 2017. Resilience of Pollen and Post-Flowering Response in Diverse Sorghum Genotypes Exposed to Heat Stress under Field Conditions. Crop Science. 57. 10.2135/cropsci2016.08.0706. Maduraimuthu, D., R. Perumal, I. Ciampitti, S.K. Gupta, P.V.V. Prasad, 2017. Quantifying pearl millet response to high temperature stress: thresholds, sensitive stages, genetic variability and relative sensitivity of pollen and pistil: Response of pearl millet to high temperature. Plant, Cell & Environment. 10.1111 Shakeel, A., F. Muhammad, A. Muhammad, Folkard, S.V.K. Jagadish, P.V.V. Prasad, K. Siddique. 2017. Thermal stress impacts reproductive development and grain yield in rice. Plant Physiology and Biochemistry. 115. 5772. 10.1016/j.plaphy.2017.03.011. Assefa, Y., P.V.V. Prasad, P. Carter, M. Hinds, G. Bhalla, R. Schon, M. Jeschke, S. Paszkiewicz, I. Ciampitti, I. 2017. A New Insight into Corn Yield: Trends from 1987 through 2015. Crop Science. 57. 2799-2811. 10.2135/cropsci2017.01.0066. Sun, A., I. Somayanda, J. Sunoj, K. Singh, P.V.V. Prasad, K. Gill, S.V.K. Jagadish. 2017. Heat stress during flowering affects time of day of flowering, seed-set, and grain quality in spring wheat (Triticum aestivum L.). Crop Science. 58. 10.2135/cropsci2017.04.0221. Maduraimuthu, D., R. Perumal, S.V.K. Jagadish, I. Ciampitti, R. Welti, P.V.V. Prasad. 2017. Sensitivity of sorghum pollen and pistil to high temperature stress. Plant Cell and Environment. . 10.1111/pce.13089. Tack, J., J. Lingenfelser, and S.V.K. Jagadish. 2017. Disaggregating sorghum yield reductions under warming scenarios exposes narrow genetic diversity in US breeding programs. Proceedings of the National Academy of Sciences 114(35) DOI. 10.1073/pnas.1706383114 Fu, J., R.L. Bowden, S.V.K. Jagadish, B.S. Gill. 2017. Genetic variation for tolerance to terminal heat stress in Dasypyrum villosum Crop Science 57(5) DOI. 10.2135/cropsci2016.12.0978 Jagadish, S.V.K., R.N. Bahuguna, D. Maduraimuthu, R. Gamuyao, P.V.V. Prasad, P.Q. Craufurd. 2016. Implications of High Temperature and Elevated CO2 on Flowering Time in Plants. Frontiers in Plant Science 7(1010). DOI.10.3389/fpls.2016.00913 Desai J.S., R.C. Sartor, L.L. Lawas, S.V.K. Jagadish, C. Doherty. 2017. Improving Gene Regulatory Network Inference by Incorporating Rates of Transcriptional Changes. Scientific Reports. DOI:10.1038/s41598-017-17143-1 Hu Y., Q. Wu, Z. Peng, S.A. Sprague, W. Wang, J. Park, E. Akhunov, S.V.K. Jagadish, P.A. Nakata, N. Cheng, K.D. Hirschi, F.F. White, S. Park. 2017. Silencing of OsGRXS17 in rice improves drought stress tolerance by modulating ROS accumulation and stomatal closure. Scientific Reports, doi:10.1038/s41598-017-16230-7 Chaturvedi A.K., R.N. Bahuguna, D. Shah, M. Pal, S.V.K. Jagadish. 2017. High temperature stress during flowering and grain filling offsets beneficial impact of elevated CO2 on assimilate partitioning and sink-strength in rice. Scientific Reports DOI:10.1038/s41598-017-07464-6


Progress 10/01/15 to 09/30/16

Outputs
Target Audience:Crop scientists, crop advisors, public agency representatives and the farming public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Three graduate students (A. Ehtaiwesh, S. Narayanan, and K. Shroyer) and two postdoctoral research associates (M. Djanaguiraman and J. Sunoj) worked on projects related to the objectives of this project. Investigators pursued professional development by participating in conferences, symposia and workshops noted above. How have the results been disseminated to communities of interest?Project investigators presented findings at conferences and symposia including NC 1200 Annual Meeting, 11/7/2015, St. Louis, MO; American Society of Agronomy Annual Meetings, 11/15-18/2015, Plant and Animal Genome Conference, 1/9-13/2016, San Diego, CA; and Sorghum Improvement Congress of North America, 9/19-21/2016, Manhattan, KS. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? A corn hybrid (DKC47-27RIB) was grown in controlled environments, under six sets of temperature conditions (31:29, 35:25, 29:21; 36:34, 40:30, and 44:26; oC day:night). After 40 days, significant changes were observed in night time respiration, plant height, total leaf area and total dry matter accumulation. Leaf respiration at night decreased with more cool night conditions. However, sugar and starch content, as well as plant height, total leaf area and total dry matter accumulation increased with cooler night conditions. No differences were detected in photosynthesis, photochemical efficiency and chlorophyll content. A strong negative correlation was found between night respiration and total dry matter accumulation, leaf area, reducing sugars and starch. The results suggest that night time respiration drives the negative impact on maize growth as a result of increased night temperature. Twelve genotypes of winter wheat were grown in controlled environments, at optimum temperature (25:15 oC day:night) until booting (panicle, or seed head nearly emerged from leaf sheath). At booting, plants were irrigated with three different salinity levels (0, 60, or 120 mM NaCl) and exposed to optimum or high temperature (25:15 oC day:night and 35:20 oC day:night) for 10 days. High temperature stress, when combined with salinity during booting stage, negatively affected the growth and development of the plant, resulting in lower plant productivity. Greater impact on yield was observed with the combined stresses compared with salinity alone or high temperature alone. Salinity and high temperature treatments decreased leaf level photosynthesis, seed set, grain number and grain yield per spike (panicle). In addition, there was considerable variation in high temperature and salinity tolerance among winter wheat genotypes for leaf level photosynthesis, seed set, grain number and grain yield. Winter wheat genotypes Ventnor (heat tolerant) and Karl 92 (heat susceptible) were grown at optimum temperatures (25:15 °C, day:night) until the onset of flowering. Thereafter, plants were exposed to high night (25/24 °C day:night), high day (35:15 °C day:night), high day and night (35:24 °C day:night), or optimum temperatures for 12 days. We measured 165 glycerolipids and sterol derivatives under optimum and high day and night temperatures in wheat pollen on the third day of stress. Levels of polar lipid fatty acyl chain unsaturation were lower under high temperatures, compared to optimum temperature. The lower unsaturation was predominantly due to lower levels of 18:3 and higher levels of 18:1 and 16:0 acyl chains. Levels of 18:3-containing triacylglycerols increased 3-fold/more under high temperatures, consistent with their possible role in sequestering fatty acids during membrane lipid remodeling. Phospholipids containing odd-numbered or oxidized acyl chains accumulated in leaves under high temperatures. Sterol glycosides and 16:0-acylated sterol glycosides were higher under high temperatures than optimum temperature. Correlation analysis of lipid levels revealed 13 groups of co-occurring lipids, which are up-or-down-regulated together through time during high temperature stress. Current knowledge of lipid metabolism suggests that the lipids in each group co-occur because they are regulated by the same enzyme(s). Taken together, the data demonstrate that wheat leaf lipid composition is altered by high day and night temperature stress, that some lipids are particularly responsive to high temperatures, and co-occurring lipids represent groups that can be explained by coordinated metabolism. Soybean genotypes (114 varieties), released from the 1920s through 2010 were evaluated for productivity and physiological characteristics including canopy temperature, leaf chlorophyll con­tent, pollen germination, electrolyte leakage and leaf antioxidants. Among genotypes seed yield increased with year of release, as well as chlorophyll content. Canopy tempera­ture decreased with year of release. Canopy temperature and chlorophyll content changed over time along with changes in maturity, plant height, lodging, and disease resistance. The changes have resulted in corre­sponding improvements in seed yield. The rela­tionships between canopy temperature and chlorophyll content with seed yield provide support to intentionally select for these traits in plant breeding programs as a possible means to improve genetic gain. Genetic mapping studies were conducted with grain sorghum, seeking genetic links to physiological traits including grain yield, flowering time, chlorophyll content, chlorophyll fluorescence and duration of green leaves. Complementary methods revealed fifteen genetic links to the traits studied. A genetic link for grain yield under normal and stressed conditions was identified in chromosome 1. Genetic links for flowering time were found in chromosomes 2, 6 and 9. Green leaf duration was linked to genes in chromosomes 3 and 4. A separate study identified a genetic link (Locus 7-2) to germination of sorghum seeds under cold conditions (12 oC). These identified genetic linkages could be used to improve grain yield, flowering time and green leaf duration in sorghum molecular breeding programs.

Publications

  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Bheemanahalli, R., Sathishraj, R., Tack, J., Nalley, L.L., Muthurajan, R., Jagadish, K.S.V*. (2016). Temperature thresholds for spikelet sterility and associated warming impacts for sub-tropical rice. Agric. For. Meteorol. 221, 122130.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Jagadish, S.V.K, Bahuguna, R.N., Djanaguiraman, M., Gamuyao, R., Prasad, P.V.V., Craufurd, P.Q. 2016. Implications of high temperature and elevated CO2 on flowering time in plants. Front. Plant Sci. doi: 10.3389/fpls.2016.00913.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Keep NR, Schapaugh WT, Prasad PVV, Boyer JE. 2016. Changes in physiological traits in soybean with breeding advancements. Crop Science 56: 122-131
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Narayanan S, Tamura P, Roth M, Prasad PVV, Welti R. 2016. Wheat leaf lipids during heat stress: I. High day and night temperatures results in major lipid alternations. Plant Cell and Environment 39: 787-803.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Narayanan S, Prasad PVV, Welti R. 2016. Wheat leaf lipids during heat stress: II. Lipid experiencing coordinated metabolism are detected by analysis of lipid co-occurrence. Plant Cell and Environment 39: 608-317.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Ocheltree TW, Nippert JB, Prasad PVV. 2016. A safety vs. efficiency trade-off identified in the hydraulic pathway of grass leaves is decoupled from photosynthesis, stomatal conductance, and precipitation. New Phytologist 210: 97-107.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Prasad PVV, Djanaguiraman M, Perumal R, Ciampitti IA. 2015. Impact of high temperature stress on floret fertility and individual grain weight of grain sorghum: sensitive stages and thresholds for temperature and duration. Frontiers in Plant Science 6: 820 (doi: 10.3389/fpls.2015.00820).
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Sukumaran S, Li X, Zhu C, Bai G, Perumal R, Tuinstra MR, Prasad PVV, Mitchell S, Tesso T, Yu J. 2016. QTL mapping for grain yield, flowering time, and stay-green traits in sorghum using genotyping-by-sequencing markers. Crop Science 56: 1429-1442.
  • Type: Journal Articles Status: Published Year Published: 2016 Citation: Upadhyaya HD, Wang Y, Dintyala S, Dwivedi SL, Prasad PVV, Burrell A, Klein R, Morris G, Klein P. 2016. Association mapping of germinability and seedling vigor in sorghum under controlled low temperature conditions. Genome 59: 137-145.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Ehtaiwesh, A., P.V.V. Prasad, M.B. Kirkham, A. Fritz, and S. Park. 2015. The combined effect of salinity and high temperature on winter wheat at booting. Agronomy Abstracts. American Society of Agronomy, 11/15-18/2015, Minneapolis, MN.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Jagadish, K., T. Ishimaru, C. Ye. 2015. Rice races against rising temperaturesachievements, opportunities and challenges. Agronomy Abstracts. American Society of Agronomy, 11/15-18/2015, Minneapolis, MN.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Jagadish SVK, Kadam N, Bheemanahalli RR, Prasad PVV. 2016. Exploring root morphological and anatomical plasticity among cereals to enhance adaptation to water limited conditions. Oral presentation Plant and Animal Genome Conference (PAG XXIV), Jan 9-13, San Diego, CA.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Narayanan, S., R. Welti, and P.V.V. Prasad. 2015. High day and night temperature stress results in lipid alterations in wheat pollen. Agronomy Abstracts. American Society of Agronomy, 11/15-18/2015, Minneapolis, MN.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Narayanan, S., R. Welti, and P.V.V. Prasad. 2015. High day and night temperatures result in major lipid alterations in wheat and co-occurring lipids represent groups that are explained by coordinated metabolism. Agronomy Abstracts. American Society of Agronomy, 11/15-18/2015, Minneapolis, MN.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Sunoj, J. K.J. Shroyer, K. Jagadish, and P.V.V. Prasad. 2015. Diurnal temperature amplitude alters physiological and biochemical responses of maize during the vegetative stage. Agronomy Abstracts. American Society of Agronomy, 11/15-18/2015, Minneapolis, MN.


Progress 10/01/14 to 09/30/15

Outputs
Target Audience:Crop scientists, crop advisors, public agency representatives and the farming public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Two graduate students (S. Narayanan, G. Pradhan) and one postdoctoral research associate (M. Djanaguiraman) worked on projects related to the objectives of this project. Investigators pursued professional development by participating in conferences, symposia and workshops noted above. How have the results been disseminated to communities of interest?Project investigators presented findings at conferences, symposia, workshops and field days including ASA Annual Meetings, 11/2-5/14, Long Beach, CA; NC 1200 Annual Meeting, 11/14/14, Kansas City, MO; Sorghum Improvement Conference of North America, 9/2/15, Manhattan, KS. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We compared the effects of high daytime and high night-time temperatures during anthesis on physiological (chlorophyll fluorescence, chlorophyll concentration, leaf level photosynthesis, and membrane damage), biochemical (reactive oxygen species (ROS) concentration and antioxidant capacity in leaves), growth and yield traits of wheat genotypes (Ventnor and Karl 92) (Narayanan et al., 2015). Plants were grown at optimum temperatures (25/15C, maximum/minimum) until the onset of anthesis. Thereafter, plants were exposed to high night-time (HN, 25/24C), high daytime (HD, 35/15°C), high daytime and night-time (HDN, 35/24C) or optimum temperatures for 7 days. Compared with optimum temperature, HN, HD and HDN increased ROS concentration and membrane damage and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. Impact of HN and HD was similar on all traits. Greater impact on seed set, grain number and grain yield per spike was observed at HDN compared with HN and HD. These results suggest that HN and HD during anthesis cause damage of a similar magnitude to winter wheat. We identified the most sensitive stages of reproductive development to high temperature stress and quantified the thresholds for temperature and duration for floret fertility and individual grain weigh in sorghum (Prasad et al., 2015). Periods between 10 and 5 d before anthesis; and between 5 d before- and 5 d after-anthesis were most sensitive to high temperatures causing maximum decreases in floret fertility. Mean daily temperatures >25°C quadratically decreased floret fertility (reaching 0% at 37°C) when imposed at the start of panicle emergence. Temperatures ranging from 25 to 37°C quadratically decreased individual grain weight when imposed at the start of grain filling. Both floret fertility and individual grain weights decreased quadratically with increasing duration (0-35 d or 49 d during floret development or grain filling stage, respectively) of high temperature stress. In field conditions, imposition of temperature stress (using heat tents) during floret development or grain filling stage also decreased floret fertility, individual grain weight, and grain weight per panicle. A limited-transpiration (TRlim) trait has been identified in many crop species, including sorghum (Sorghum bicolor (L.) Moench), that results in restricted transpiration rate under high vapor pressure deficits (VPD). The benefit of TRlim is that under high midday-VPD conditions crop water loss is limited so that there is water conservation and positions the crop to better withstand later-season drought. Previous studies performed at 31°C found that TRlim was commonly expressed among sorghum genotypes. However, it is uncertain how applicable these previous results obtained at 31°C might be at higher temperature that may exist at midday in regions where sorghum is commonly grown. The current study tested for the expression of TRlim at 37°C in 16 sorghum genotypes previously found to express the trait at the lower temperature. Only three of the genotypes sustained expression of TRlim at 37°C. These results indicate that for environments where temperature may commonly reach or exceed 37°C, sorghum genotypes have been favored that acclimate to the high temperature by losing the TRlim trait. In conditions in which very high temperatures threaten crop heat stress, those genotypes that lose the TRlim trait at high temperature may be more desirable since increasing transpiration rates at these temperatures can result in leaf cooling. We found that wheat grown in water-deficient intensive cropping systems had less biomass productivity relative to crop water use. This finding contrasted with evidence of greater transpiration efficiency for wheat in intensive systems, indicated by smaller grain carbon isotope (13C) discrimination (DELTA). The reduced water productivity at the cropping system level was attributed to a smaller transpiration fraction of crop water use for wheat in the more intensive cropping systems.

Publications

  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Narayanan, S., Prasad, P.V.V., Fritz, A.K., Boyle, D.L., and Gill, B.S. 2015. Impact of high nighttime and high daytime temperature stress on winter wheat. Journal of Agronomy and Crop Science 201, 206-218. Prasad, P.V.V., Djanaguiraman, M., Perumal, R., and Ciampitti, I.A. 2015. Impact of high temperature stress on floret fertility and individual grain weight of grain sorghum: sensitive stages and thresholds for temperature and duration. Frontiers in Plant Science 6,820.
  • Type: Journal Articles Status: Published Year Published: 2015 Citation: Godar, A.S., Varanasi, V.K., Betha, S., Prasad, P.V.V., Thompson, C.R., and Mithila, J. 2015. Physiological and molecular mechanisms of differential sensitivity of palmer amaranth (Amaranthus palmeri) to mesotrione at varying growth temperatures. PloS One 10(5), e0126731. Pradhan, G.P., and Prasad, P.V.V. 2015. Evaluation of wheat chromosome translocation lines for high temperature stress tolerance at grain filling stage. PLoS One 10(2), e0116620. Riar, M.K., Sinclair, T.R., and Prasad, P.V.V. 2015. Persistence of limited-transpiration-rate trait in sorghum at high temperature. Environmental and Experimental Botany 115, 58-62.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Aiken, R.M., G. Zhang and T.J. Martin. 2014. Carbon isotope discrimination, selecting for productivity and water use efficiency in wheat. Agronomy Abstracts. 409-6. Prasad, P.V.V. and D. Maduraimuthu. 2014. Advances in understanding of physiological and biochemical responses of crop plants to high temperature stress. Agronomy Abstracts. 111-3. Narayanan, S., P.V.V. Prasad and R. Welti. 2014. Membrane lipid composition under high temperature stress in wheat. Agronomy Abstracts. 279-4. Gill, K., S. Bakshi, A. Sharma, A. Mohan, K. Singh, J. Saini, P.V.V. Prasad, J. Jaiswal, K.S. Dhugga, P.K. Gupta, R. Kumar, S. Sareen, H. Singh, H.S. Balyan, K.K. Narayanan, V. Chinnusamy and R. Singh. 2014. Improving heat tolerance of wheat by combining genomic, molecular and physiological approaches. Agronomy Abstracts. 280-4.


Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Crop scientists, crop advisors, public agency representatives and the farming public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two graduate students (S. Narayanan, G. Pradhan) and one postdoctoral research associate (M. Djanaguiraman) worked on projects related to the objectives of this project. Investigators pursued professional development by participating in conferences, symposia and workshops noted above. How have the results been disseminated to communities of interest? Project investigators presented findings at conferences, symposia, workshops and field days including ASA Annual Meetings, 11/4-6/13, Tampa, FL; NC 1200 Annual Meeting, 11/23/13, Lincoln, NE; K-State Center for Sorghum Improvement, 7/7/2014; NWREC Fall Field Day, 9/4/2014, Colby, KS. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? 1. The response of eight sorghum genotypes to high temperature was quantified under controlled environment conditions. High temperature stress increased leaf and pollen oxidative stage. Sorghum genotypes differed for percentage seed-set under high temperature stress. Genotypes with high maximum temperature and pollen germination had improved percentage of seed-set under high temperature stress. This research suggest that HT stress tolerant genotypes can be identified by quantifying oxidative damage in pollen grains and by measuring pollen germination, seed-set percentage and grain yield at HT. 2. We partitioned leaf hydraulic resistance of six genotypes of Sorghum bicolor L. (Moench) into leaf specific hydraulic resistance within the large longitudinal veins and outside the large veins. We correlated these resistances with the response of stomatal conductance and photosynthesis to drought. Experimental results indicate that the hydraulic resistance of leaf tissue limits the maximum rate of transpiration and photosynthesis. As the soil dries, maintenance of cell turgor and function was affected by the ability of leaf veins to move water long distances, i.e. small hydraulic resistance within large longitudinal veins. Genotypes with increased hydraulic resistance through the leaf had less evapotranspiration resulting in more conservative water use. These results illustrate that leaf resistance characteristics can alter water use and plant responses to declining soil moisture. 3. We found significant genetic variations for grain carbon isotope (13C) discrimination (CID) among wheat breeding lines and a significant and positive correlation between grain CID and yield across three of four field trials conducted under various environmental conditions. These results indicate that grain CID could be a useful selection criterion for grain yield improvement under moderate drought stress, especially post-anthesis drought, in temperate semi-arid regions. The positive relationships of CID and test weight suggests further investigation of CID as an indicator of enhanced translocation capacity.

Publications

  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Djanaguiraman, M., P.V.V. Prasad, M. Murugan, U.K. Reddy. 2014. Physiological differences among sorghum (Sorghum bicolor L. Moench) genotypes under high temperature stress. Environmental and Experimental Botany 100, 43-54. Hebbar, K.B., J. Rane, S. Ramana, N.R. Panwar, S. Ajay, A. Subba Rao, and P.V.V. Prasad. 2014. Natural variation in the regulation of leaf senescence and relation to N and root traits in wheat. Plant and Soil 378, 99-112. Kadam, N.N., G. Xiao, R.I. Melgar, R.N. Bahuguna, C. Quinones, A. Tamilselvan, P.V.V. Prasad, and S.V.K. Jagadish. 2014. Agronomic and physiological response to high temperature, drought and elevated carbon dioxide interactions in cereals. Advances in Agronomy 127, 111-156. Mahama, G.Y., P.V.V. Prasad, D.B. Mengel, and T.T. Tesso. 2014. Influence of nitrogen fertilizer on growth and yield of sorghum hybrids and inbred lines. Agronomy Journal 106, 1623-1630. Narayanan, S., R.M. Aiken, P.V.V. Prasad, Z. Xin, G. Paul, and J. Yu. 2014. A simple quantitative model to predict leaf area index in sorghum. Agronomy Journal 106, 219-226. Narayanan, S., A. Mohan, K.S. Gill, and P.V.V. Prasad. 2014. Variability of root traits in spring wheat germplasm. PLoS One 9(6), e100317. Narayanan, S. and P.V.V. Prasad. 2014. Characterization of a spring wheat association mapping panel for root traits. Agronomy Journal 106, 1593-1604. Ocheltree, T.R., J.B. Nippert, M.B. Kirkham, and P.V.V. Prasad. 2014. Partitioning hydraulic resistance in sorghum bicolor leaves reveals unique correlations with stomatal conductance during drought. Functional Plant Biology 41, 25-36. Ocheltree, T.R., J.B. Nippert, and P.V.V. Prasad. 2014. Stomatal response to changes in vapor pressure deficit reflect tissue-specific differences in hydraulic conductance. Plant Cell and Environment 37, 132-139. Paul, G., P.H. Gowda, P.V.V. Prasad, T.A. Howell, and R.M. Aiken. 2014. Investigating the influence of roughness length for heat transport (zoh) on performance of SEBAL in semi-arid irrigated and dryland agricultural systems. Journal of Hydrology 209, 231-234. Singh, P., N. Swamikannu, S.P. Traore, K.J. Boote, H.F.W. Rattunde, P.V.V. Prasad, N.P. Singh, K. Srinivas, and C. Bantilan. 2014. Quantifying potential benefits of drought and heat tolerance in rainy season sorghum for adapting to climate change. Agricultural and Forest Meteorology185, 231-234.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Aiken, R.M. and P.I. Coyne. 2013. Inferring Relative Heat, Water Vapor and Carbon Exchange From Digital Images of Vegetative Canopies. Agronomy Abstracts. 201-6. Aiken, R.M. and V. Prasad. 2013. Seeking gains in crop water productivity. Annual meeting, NC 1200 "Regulation of Photosynthetic Processes." Aiken, R.M. 2014. High Throughput Screening Tools to Detect Advanced Sorghum Canopy Traits. K-State Center for Sorghum Improvement. Aiken, R.M. 2014. Water Use and Productivity of Dryland Corn and Grain Sorghum. NWREC Fall Field Day.


Progress 05/29/13 to 09/30/13

Outputs
Target Audience: Crop scientists, crop advisors, public agency representatives and the farming public. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Two graduate students (S. Narayanan, G. Pradhan) and one postdoctoral research associate (M. Djanaguiraman) contributed to project objectives. Investigators pursued professional development by participating in conferences, symposia and workshops noted above. How have the results been disseminated to communities of interest? Project investigators presented findings at conferences, symposia, workshops and field days including ASA Annual Meetings, 10/22-24/12, Cincinnati, OH; NC 1200 Annual Meeting, 11/17/12, Reno, NV; National Sunflower Association Research Forum, 1/7/13, Fargo, ND; Cover Your Acres Winter Conference, 1/ 15-16/2013, Oberlin, KS; No-Till Oklahoma Conference, 2/19-20/2013, Norman, OK; Central Plains Irrigation Conference, 2/26-27/2013, Kearney, NE; Ogallala Aquifer Program workshop 3/5-7/13, Amarillo, TX; NWREC Field Day, 6/4/2013, Colby, KS; CIMMYT Workshop "Modeling Wheat Response to High Temperature," 6/19-21/2013, El Batan, Mexico.; "Tear-Down-the-Walls" High Plains Regional Agronomists meeting, 8/14-15/2013, Colby, KS; SWREC Field Day 8/29/2013, Garden City, KS; Sorghum Improvement Conference of North America, 8/27-29/2013 Lubbock, TX; (see presentations). In addition, research results have been highlighted in professional publications (Short-statured sunflower: 'Sunflower' magazine 2012; Wheat water productivity manuscript featured in Certified Crop Advisor profile https://www.certifiedcropadviser.org/ and Advances in Engineering profile http://advanceseng.com/general-engineering/; Sorghum radiation and water use manuscript featured in CSA news (June, 2013). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Controlled environment and field studies led to improved understanding of genetic variability, mechanisms, and field responses associated with improved tolerance of drought (water use efficiency and water availability) and supra-optimal temperature. In sorghum, water use efficiency (WUE) was more strongly associated with biomass than water use. Stay-green trait in sorghum was not associated with sensitivity of transpiration to either soil drying or vapor pressure deficits. High day or nighttime temperatures increased respiration rates and decreased photosynthesis, pollen germination and seed-set percentage in soybean. High temperature stress caused biochemical, anatomical and morphological changes in soybean pollen grains, leading to decreased pollen germination and seed-set. Water deficits reduced wheat productivity responses to an increment of water use and impaired multiple components of grain formation. High-temperature stress significantly decreased chlorophyll content, damaged thylakoid membrane (indicated by chlorophyll fluorescence), leading to decreased photosynthesis and grain yield. Measurement of chlorophyll loss or chlorophyll fluorescence can help determine genotypes that are tolerant to high temperature stress. There was genetic variability for high temperature tolerance in wheat. New potential sources of heat-tolerant genotypes in wheat included wild relatives of wheat, chromosomal substitution lines and synthetic wheat collections. Several germplasm collections (spring and winter wheat collections about 700 lines) were screened for root traits that may play significant roles in drought tolerance and yield improvement under controlled environments. High day- or nighttime temperatures increased leaf respiration and decreased photochemical quenching, electron transport rate and leaf photosynthesis, and pollen germination. Overall, high temperatures during flowering decreased leaf photosynthesis and pollen germination, leading to decreased pod-set percentage and seed weight. High temperature stress resulted in deformed pollen grains with thicker exine walls and disintegrated tapetum layer leading to decreased pollen germination and pod-set percentage. Satellite images, combined with weather data, can quantify crop water use over large (multi-state) regions. These techniques can be quite accurate for well-watered crops, but strongly biased (under-estimating crop water use) for crops affected by soil water deficits. This bias can be corrected by incorporating effects of turbulent transfer into the simulation model. Soil water deficits can affect plant development and subsequent yield formation. Eight sorghum genotypes were evaluated for biomass production, WUE, and radiation use efficiency (RUE) and to test whether the differences in WUE among sorghum genotypes were associated with increased biomass production or decreased water use under field conditions. It was observed that WUE was more strongly correlated with biomass production than to water use. These results imply that it is possible to improve WUE without compromising biomass production. In grain sorghum, the potential drought tolerant trait of slow wilting was identified in several lines. This trait was further being evaluated under controlled environment and field conditions to understand the mechanisms associated with the slow-wilting trait. Enhancing the duration of green leaf area or stay green has been widely investigated in sorghum for improving drought tolerance. In addition, there are two additional mechanisms that can result in soil water conservation to allow greater water availability during seed fill. One mechanism is an earlier decrease in transpiration with soil drying so that the rate of soil water loss is decreased earlier in the soil drying cycle. The second mechanism is a limitation on transpiration rate at high vapor pressure deficit (VPD) so that soil water is conserved on days when midday VPD is high. Evaluation of genotypes that consistently expressed the stay-green trait and genotypes that did not exhibit this trait was compared with the above two mechanisms. Results showed that there was no evidence in the selected pool of genotypes, that the stay-green trait was closely linked with either mechanisms of water conservation. The impact of leaf hydraulic conductance on water use characteristics was explored by comparing two contrasting sorghum genotypes. Genotype SC15 had a much lower leaf conductance than genotype SC1205. Results demonstrated that low hydraulic conductance in SC15 was associated with conservative water use by restricting transpiration at higher soil water content during soil drying and under high VPD (above 2.1 kPa). Genotype SC1205 did not show such response. Tests with inhibitors indicate that these differences may be linked to differences between their aquaporin populations.

Publications

  • Type: Journal Articles Status: Published Year Published: 2013 Citation: Choudhary, S., Mutava, R.N., Shekoofa, A., Sinclair, T.R., and Prasad, P.V.V. 2013a. Is the stay-green trait in sorghum a result of transpiration sensitivity to either soil drying or vapor pressure deficit? Crop Sci. 53:2129-2134. Choudhary, S., Sinclair, T.R., and Prasad, P.V.V. 2013b. Hydraulic conductance of intact plants of two contrasting sorghum lines SC15 and SC1205. Funct. Plant Biol. 40:730-738. Djanaguiraman, M., Prasad, P.V.V., and Schapaugh, W.T. 2013a. High day and night temperature alters leaf assimilation, reproductive success and phosphatidic acid of pollen grain in soybean (Glycine max L. Merr.). Crop Sci. 53:1594-1604. Djanaguiraman, M., Prasad, P.V.V., Boyle, D.L., and Schapaugh, W.T. 2013b. Soybean pollen anatomy, viability and pod set under high temperature stress. J. of Agron. Crop Sci. 199:171-177. Narayanan, S., Aiken, R.A., Xin, Z., Prasad, P.V.V., and Yu, J. 2013. Water use efficiencies in sorghum. Agron. J. 105:649-656. Rao, S.S., Patil, J.V., Prasad, P.V.V., Reddy, D.C.S., Mishra, J.C., Umakanth, A.V., Reddy, B.V.S., and Kumar, A.A. 2013. Sweet sorghum planting effects on stalk yield and sugar quality in semi-arid tropical environment. Agron. J. 105:1458- 1465. Singh, R.P., Reddy, K.R., and Prasad, P.V.V. 2013. Impact of changing climate and climate variability on seed production and seed industry. Adv. in Agron. 118:49-110.
  • Type: Books Status: Published Year Published: 2013 Citation: Djanaguiraman M. and Prasad P.V.V. 2013. High temperature stress. On: Plant Genetic Resources and Climate Change (Eds. Jackson, M., Ford-Lloyd, B.V. and Perry, M.L.). CABI. pp. 201-220.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Aiken, R.M. D1 corn hybrid response to limited irrigation Tear Down the Walls Annual Meeting, Colby, KS, 8/15/13. Aiken, R.M. and Coyne, P.I. 2013. Inferring Relative Heat, Water Vapor and Carbon Exchange from Digital Images of Vegetative Canopies. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI. Aiken, R., Lamm, F., and Seiler, G. 2013. Sunflower canopy and oilseed yield formation under deficit irrigation. National Sunflower Association Research Forum, Fargo, ND 1/7/13. Aiken, R.M., Perumal, R., and Prasad, V. Boosting Sorghum Yields with Novel Productivity Traits SICNA meetings, Lubbock, TX, 8/27/2013. Djanaguiraman, M., Prasad, P.V.V., Marimuthu, M., and Reddy, U.K. 2013. Differential response of sorghum genotypes to high temperature stress is mediated through oxidative damage in leaves and pollen grains. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI. Prasad, P.V.V. and Djanaguiraman, M. 2013. Impact of season-long and short-episodes of high temperature stress on growth and development of wheat. Proceedings of the Workshop Modeling Wheat Response to High Temperature, 19-21 June, CIMMYT, El Batan, Mexico. Prasad, P.V.V., Reddy, K.R., and Djanaguiraman, M. 2013. Response of soybean and cotton to climate change factorscarbon dioxide, temperature and water. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI.
  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Narayanan, S., Prasad, P.V.V., Shroyer, K., Gill, B.S., and Fritz, A. 2013. Characterization of a spring wheat association mapping panel for root traits. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI. Narayanan, S., Prasad, P.V.V., Welti, R., and Fritz, A. 2013. Comparative responses of wheat to high day- and/or night-time temperature stress during flowering. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI. Shroyer, K. and Prasad, P.V.V. 2013. Estimation of yield and physiological status of spring and winter wheat using canopy spectral reflectance. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI. Shroyer, K. and Prasad, P.V.V. 2013.The effect of heat stress on the seed filling rate and duration of three winter wheat (Triticum aestivum L.) cultivars [Armor, Jagger and Karl 92]. In Annual meetings abstract (CD-ROM). ASA, CSSA, and SSA, Madison, WI.