Recipient Organization
CLEMSON UNIVERSITY
(N/A)
CLEMSON,SC 29634
Performing Department
Plant & Environmental Sciences
Non Technical Summary
Saltwater is a threat to sustainable organic rice production in coastal regions. Climate change effects are seen in rising sea level, increasing salinity in tidal rivers, and flooding of cultivable lands with saltwater. This project's long-term goal is to increase organic rice production of coastal South Carolina (SC) by bringing salt-intruded lands to cultivation. We will accomplish this goal by completing the following objectives: (1) Evaluating the impact of saltwater and native weed pressure on plant vigor among diverse rice cultivars/germplasm in greenhouse. (2) Validating salt tolerance and performance of select cultivar in organic-plot-trials. (3) Evaluating agronomic performance of salt-tolerant cultivar in salt-affected, organic farms in coastal SC. (4) Developing enterprise budgets for organic rice production. (5) Evaluating soil and water quality improvements under organic rice production. (6) Developing salt-tolerant pre-breeding lines with 'Carolina Gold' type traits. Salt-tolerant cultivar selections will be trialed on-farm to determine productivity and grain quality. New, salt-tolerant cultivars will be introduced, expanding potential for organic rice production in salt-intruded lands. Economics of organic rice production detailed, enabling growers to make informed decisions. Ultimately, new cultivars will expand acreage under organic rice production, while ensuring the economic stability of producers and enhancing ecosystem services. This project will address Priority Areas (1) effects of organic practices on soil quality and fertility and understanding of weeds, (2) technologies to document the mitigation ability of organic crops, and (3) cultural practices and cultivars to remove NOP-cited substances and evaluate efficacy based on resulting productivity.
Animal Health Component
45%
Research Effort Categories
Basic
45%
Applied
45%
Developmental
10%
Goals / Objectives
The overall goal of this project is to increase organic rice production in coastal SC on salt-impacted lands. We will accomplish this goal by completing the following objectives:Objective 1: Evaluate the impact of saltwater and native weed pressure on plant vigor among diverse rice cultivars/germplasm in greenhouse.HA1: Saltwater will suppress weeds when salt-tolerant rice cultivars are grown under organic conditions.We will determine the effect of saltwater (representative of organic plot and on-farm locations) and rice cultivar on competition between native weeds and rice crops in pots. We surveyed various SC rice fields and determined the most common weed species are goosegrass (Eleusine indica) and hemp sesbania (Sesbania herbacea), which will be used in the experiments. The greenhouse study will be at the Coastal REC and at Clemson University in Year 1.Objective 2: Validate salt tolerance and performance of select cultivar in organic plot trials.HA2: Salt-tolerant cultivar will grow productively using saline irrigation and organic management practices in field plots.We will use the most salt-tolerant cultivar from the greenhouse trials and the susceptible, commercial cultivar, 'Carolina Gold'. We will determine the cultivar salt tolerance in addition to yield, grain quality, disease rankings, and overall vigor under field conditions. The plots are on the Yonges loamy fine sand, representative soil found in large portions of coastal SC counties. The plots have entered organic transition to become organic certified and have been under organic conditions for the past two years. The plots are chosen due to its proximity to a tidal salt marsh that often inundates the field, especially under high water events. These plots have a history of poor growth of vegetables and cover crops due to saltwater intrusion. This field's proximity to tidal saltwater and our freshwater irrigation infrastructure will allow varied salinity level scenario testing. Plot trials will be conducted during Year 2 and repeated in Year 3.Objective 3: Evaluate agronomic performance of salt-tolerant rice cultivar in salt-affected, organic farms in coastal South Carolina.HA3: Salt-tolerant rice varieties will yield well in organic farms affected by saltwater intrusion in coastal SC.We will grow the same salt-tolerant cultivar used in organic plot trials and in a saltwater intruded agroecosystem. If the rice cultivar exhibits better salt tolerance than the weeds present at the field locations, then the weeds will not be as competitive. Salinity will likely enhance rice vigor while reducing weed pressure, diminishing the need to hand-weed the fields. Rice cultivation costs will decrease with the use of marginal quality (high salinity) water and reduced weed management. On-farm trials will be conducted in four locations along the coastal plain in SC where saltwater intrusion is evident with reduced rice yields. These trials will be carried out in Year 3 and 4 at (1) Turnbridge Plantation (Marion R. Chalmers), (2) Ashe Plantation (John H. Smoak), (3) Lavington Plantation (Jimmy Hagood), (4) Toogoodoo Oyster Company (Andrew Speaker), (5) Rosebank Farms (Sidi Limehouse) and (6) Whitehouse Plantation (Donald A. Quattlebaum). All farms are either certified organic, under organic transition, or are eligible to bypass transition and enter straight into certified organic.Objective 4: Quantifying costs and potential revenue of organic rice production by developing enterprise budgets for organic rice production in coastal region.HA4: The cost of organic production in marginal salt-intruded agricultural lands will be similar to the cost of production in non-marginal land.We will develop enterprise budgets and compare the cost of different production practices, including 1) conventional saltwater rice production with current varieties, 2) conventional saltwater rice production with salt-tolerant varieties, 3) organic saltwater rice production with current varieties, and 4) organic saltwater rice production with salt-tolerant varieties. Economic analysis will be carried out in Year 2, 3, and 4.Objective 5: Evaluate soil and water quality improvements under organic rice production.HypothesisA5.1: Organic management may improve soil and water quality and crop productivity.We will collect soil and water samples periodically throughout the growing seasons from the plots (Year 2 & 3) and the growers' fields (Year 3 & 4) (both before and after rice trials initiated). Samples will be analyzed for pH, salinity, cation exchange capacity (CEC), nitrate, total N, total P, total C, microbial diversity, and common herbicides. Under organic cultivation, the leaching of nutrients should be minimal. We will analyze leachate and soil samples for salinity, pH, and CEC from the greenhouse study in Year 1 to document the basic soil and water chemistry.Objective 6: Develop salt-tolerant pre-breeding lines with 'Carolina Gold' type agronomic traits.HypothesisA6: Salt-tolerant traits from a salt-tolerant rice germplasm can be introgressed into 'Carolina Gold'.We will initiate a breeding approach to cross 'Carolina Gold' and/or 'Charleston Gold' rice with a salt-tolerant line (e.g., 'Doble Carolina' and/or 'M202') identified during screening experiments at Clemson Costal REC (Table 1). Thereafter, the desired parent cultivar i.e., 'Carolina Gold' and/or 'Charleston Gold' will be used as a recurrent parent; back-crossing will be performed to maximize the 'Carolina Gold' background traits in the salt-tolerant offspring. From a true hybrid seed, F2:3 population consisting of 250-300 recombinant inbred lines will be generated (Year 1 & 2). We will evaluate those 250-300 F3 'Carolina Gold' type rice lines in the greenhouse under tidal saltwater-stress in Year 3 & 4 at Clemson coastal REC. We will advance the individual lines comprised of salt-tolerance and 'Carolina Gold' grain quality to F7/F8 homozygous state for germplasm release and variety development for salt-intruded coastal regions' organic rice producers.
Project Methods
Objective 1The Year 1 experiment will be a factorial, completely randomized block design with five replications per treatment with one plant per pot. Experiment treatment factors include: (1) soil type [Yonges loamy fine sand, Kiawah Sandy Loam, and Edisto Muck (thermic Typic Endoaqualfs)] that represents soils of areas affected by salt intrusion and majority of areas where rice was grown historically; (2) rice cultivar (commercial standard, low-, medium-, and high-salt tolerance); (3) salinity concentration representative of organic plots and growers' fields [freshwater 0× (control) to 1× (0.375%), 2× (0.75%), and 3× (1.5%)], and (4) weed competition [rice alone, native weeds alone, native weeds seeded with rice, and native weeds transplanted at the seedling stage with rice]. Native weeds included in the objective will consist of goosegrass (Eleusine indica) and hemp sesbania (Sesbania herbacea). We will conduct preliminary studies to determine the density of weeds that would reduce biomass of 'Carolina Gold' to use as guidelines for this objective. Plants will be grown in one gallon 25 cm2 surface area pots with water retention pans to achieve complete soil saturation and will be replenished as needed. We will use Nature Safe organic OMRI certified 10-2-8 fertilizer at 150 lb/acre, which is the commercial standard.Objective 2The organic plot trials will be conducted at Coastal REC, Charleston, SC. The experimental design will consist of a completely randomized block design with four replications and a plot size of 4 ft2 with a total of 16 plants each. The treatments will be structured as factorial with four weed-free periods (0, 2, 4, and 6 weeks weed free) by two irrigation regimes (freshwater or salt water from tidal rivers) by two rice cultivars (most salt tolerant selection from the greenhouse screening and the local standard 'Carolina Gold') for a total of 16 treatments. Seedlings will be planted on 25 cm centers between row and within row. Three-foot-wide beds will act as buffers between beds so that the buffer will be wider to avoid cross treatment contamination. The two center rows will be used for data collection with all the response variables collected and analyzed as in Objective 1. Individual plots will be treated with saline water with a system of dosing pumps. Water for the treatments will come from the brackish water source located on site and diluted to salinity treatment levels described in Objective 1. Organic fertilizer application will follow the prescription as in Objective 1. This plot trial will be repeated twice (Year 2 and 3).Objective 3The on-farm trials will be conducted at four farms that are either certified organic, under organic transition, or are eligible to be certified organic. All trials will be completely randomized block design and replicated four times with plot size 16' × 16' with plants planted 25 cm within row and between rows. In addition, an additional experiment will be performed on all four sites using grower's preference rice cultivar spacing that varies from 6" × 6" to 9" × 9" within and between row spacing, respectively. All response variables mentioned in Objective 1 & 2 will be collected. Data will be analyzed as described in Objectives 1 & 2. These on-farm trials will be repeated twice (Year 3 & 4).Objective 4Since organic rice is currently a very niche market, it is important to understand its economics and develop plans for growers' production and investment costs. We will develop and disseminate/provide information to the industry towards the cost of organic rice production in marginal salt-intruded agricultural lands. This objective will be achieved with the use of enterprise budgets. The cost data required for the development of the budget will be obtained from the plot and on-farm trials in Objectives 2 and 3, and from interviews conducted with the farmers who currently produce organic rice.Objective 5Soil core samples (12 to 15 cm below the surface) from different treatments will be collected in triplicates at regular intervals (starting at pre-treatment as Time 0) for each experiment to track chemical movement and fate in the root-zone of the soil. Soil samples will be homogenized and analyzed for its pH, EC, CEC, ammonium, nitrate, total N, total P, total organic carbon, and microbial diversity (heterotrophic bacteria and fungi) using standard methods. Lysimeters will be installed on plots at 60 cm depth both at Coastal REC and four growers' farms. Water samples will be collected periodically (starting at pre-treatment as Time 0) throughout the growing season including once after the crop harvest. Leachate collected from pots (greenhouse trials) and pore water from the plots and on-farm trials will be analyzed for pH, EC, CEC, ammonium, nitrate, total N, total P, dissolved organic carbon, trace elements, cations and anions using standard methods. Ten percent of the water samples collected from plot and on-farm trials will be analyzed for select agrochemicals either GC (for volatilized chemicals) or HPLC (for non-volatilized chemicals) pesticides/herbicides panel.Objective 6We will develop 'Carolina Gold' type rice breeding lines with salt-tolerance and desirable agronomic traits for its successful organic production in coastal regions of SC. To achieve this goal, 'Carolina Gold' and/or 'Charleston Gold', highly desirable varieties for organic production in this region, will be crossed with selected salt-tolerant cultivar such as 'Doble Carolina' and/or 'M202,' (Year 1 & 2). True-hybrid seeds will be identified by marker-assisted selection and will be back-crossed to 'Carolina Gold' or 'Charleston Gold'. After backcrossing, the resulting true-hybrid F1 plant will be selected and selfed for two generations. The F2:3 population, with at least 250-300 recombinant inbred lines, will be developed by the end of Year 2.Salt-tolerance screening of this population (F3 generation) will be conducted in Year 3 using a completely randomized design and three replications at the Coastal REC as explained in the Objective 1. During salt-tolerance screening, data will be collected on agronomic traits such as: chlorosis, transplant injury, tillers number, plant height, heading date, chlorophyll content (using SPAD meter), spikelet sterility, chalkiness, seed length (L), seed width (W), L/W ratio. After evaluating the data, the top 10% of the lines (25-30 lines) with desirable salt-tolerance level, heading date, plant height, spikelet fertility, and grain quality will be selected and further evaluated in greenhouse at the Coastal REC during Year 4 of the project. During the years 3 & 4, the F2:3 generation will be advanced to homozygosity reaching at F7 or F8 generation using greenhouse at the DBNRRC. From the analysis, best breeding lines will be selected for germplasm release and/or variety development by the end of the project.