Progress 01/01/99 to 12/31/03
Outputs
Stimulating growth during the seedling and reproductive stages and suppressing growth during the reproductive stages with plant growth regulators significantly affected rice production. Seed treated with gibberellic acid improved seedling vigor. Depending on date of planting and variety, emergence was 2 to 7 days early and plant population was increased between 5 and 40%. Increasing plant population with gibberellic acid prevented 1000 to 2000 kg/ha losses in yield that occur at seeding rates below 70 kg/ha. Foliar application of gibberellic acid increased seedling height by 3 to 10 cm within 5 to 7 days after application, depending on rate and date of planting. Response was relatively consistent across varieties. Applications of auxins, cytokinins, and gibberellins from panicle initiation through grain filling increased grain yield up to 8% without affecting mature plant height or crop maturity. Applications near panicle initiation caused transient increases in plant
height of 5 to 10 cm with durations of 1 to 2 weeks. Mid and late season applications of imazethapyr and glufosinate limited seed production in red rice, a noxious weed, and had no effect on herbicide-resistant varieties. Red rice was most sensitive to imazethapyr during the early stages of panicle development. Imazethapyr arrested panicle development, resulting in 100% panicle suppression. Red rice was most sensitive to glufosinate during heading and pollination with a 95% reduction in seed formation. Prohexadione-calcium and trinexapac-ethyl reduced mature plant height between 5 and 10% depending on rate and time of application. In lodging susceptible varieties, trinexapac-ethyl reduced lodging by 30%, increased grain yield by 1000 kg/ha, and decreased harvest moisture by 10%. In the absence of lodging, trinexapac-ethyl increased grain yield by 800 kg/ha in conjunction with high seeding rates and nitrogen fertility.
Impacts
Altering plant growth and development with plant growth regulators can reduce water and herbicide use, limit costs of production, increase productivity on fewer acres, improve harvest efficiency (less fossil fuel consumption), and provide a higher quality food product.
Publications
- Jodari, F., X. Sha, S.D. Linscombe, P.K. Bollich, D.E. Groth, L.M. White, R.T. Dunand, and Q.R. Chu. 2003. Registration of 'Delmati' rice. Crop Sci. 43:435-436.
- Saichuk, J.K., R.T. Dunand et al. 2003. Plant growth regulators. In: 2004 Rice Varieties and Management Tips. La. Coop. Extn. Serv. Pub. 2270. 23 pp.
- Dunand, R.T. et al. 2003. Rice Physiology Reports. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., LSU Agricultural Center, 94:130-207.
- Dunand, R.T. 2003. Palisade and lodging in U.S. rice production. Proc. Western Pl. Growth Reg. Soc. 15:33-37.
- Dunand, R.T. 2003. Influence of growth suppression on stature reduction, panicle development, and crop production in rice. PGRSA Quarterly 31(2):96.
- Dunand, R.T., E.P. Webster, R.R. Dilly, C.T. Leon, and W. Zhang. 2003. Red rice growth suppression in Clearfield and Liberty Link rice. Proc. S. Weed Sci. Soc. 56:46.
- Dunand, R.T. 2003. Influence of growth suppression on panicle growth, plant stature, and crop production in rice. Proc. Pl. Growth Reg. Soc. of Am. 30:74.
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Progress 01/01/02 to 12/31/02
Outputs
Plant growth regulators increased seedling vigor, herbicide tolerance, and yield and reduced lodging and red rice seed production in rice. Sixteen varieties and experimental lines responded favorably to gibberellic acid, emerging up to 5 days early and increasing in height up to 60% when planted under cool (March) and warm conditions (April). Long-grain types were more responsive than medium-grain types and semidwarf types were more responsive than tall types. Imidazolinone-resistant rice (Clearfield) was especially responsive with increased stand density and subsequent increases in grain yield ranging from 100 to 1000 kg/ha, with the most dramatic effects at low seeding rates (<50 kg/ha). Cytokinins and gibberellins increased seedling height by 2 to 4 cm and yield by 100 to 200 kg/ha in rice sustaining substantial herbicide injury. Gibberellins, auxins, and cytokinins applied during the reproductive stages increased grain yield up to 8%, and labeled applications of
gibberellic acid increased grain yield by 1000 kg/ha with prepared seedbed versus notill seedbed preparation. Trinexapac-ethyl (Palisade 120 ec) reduced plant height of a tall stature variety by 7 cm and lodging from 35 to 0%. Yield increased 1000 kg/ha. Imazethapyr and glufosinate caused 100% seedhead suppression and 95% reduction in seed set in red rice in Clearfield and Liberty Link rice, respectively.
Impacts
Plant growth regulator use in rice can have a direct, positive impact on crop vigor, herbicide tolerance, weed control, lodging resistance, and grain production. Also, improving crop growth and development with plant growth regulators facilitates crop management, which decreases production costs and increases overall productivity.
Publications
- Saichuk, J.K., R.T. Dunand et al. 2002. Plant growth regulators. In: 2003 Rice Varieties and Management Tips. La. Coop. Extn. Serv. Pub. 2270. 23 pp.
- Dunand, R.T. et al. 2002. Rice Physiology Reports. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., LSU Agricultural Center, 93:181-257.
- Dunand, R.T., E.P. Webster, and S.D. Linscombe. 2002. Gibberellic acid and crop injury in Clearfield rice. Proc. S. Weed Sci. Soc. 55:117.
- Dunand, R. 2002. Impact of prohexadione-calcium on plant stature and crop production in conventional height rice. Proc. Pl. Growth Reg. Soc. of Am. 29:187.
- Dunand, R.T., S.D. Linscombe, and R.R. Dilly. 2002. Plant growth regulator offers advantages for herbicide-tolerant rice. Louisiana Agric. 45(1):16-17.
- Dunand, R.T. 2002. New plant growth regulators and their application in rice production. Proc. Western Pl. Growth Reg. Soc. 14:60-64.
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Progress 01/01/01 to 12/31/01
Outputs
Plant growth regulators improved seedling vigor, increased tolerance to herbicides, reduced height, and increased yield of rice. Seed treatment with gibberellic acid in 14 varieties and experimental lines resulted in 3 to 4 days earlier emergence, had no effect on stand density, and increased seedling height by 50%. Long-grain varieties and experimental lines were more responsive than medium-grain types and semidwarf types were more responsive than tall types. At lower than recommended seeding rates, drill-seeded imidazolinone tolerant (Clearfield) rice treated with gibberellic acid seed treatment was more tolerant to imazethapyr, resulting in 50% less injury, twice the vigor, and 8% higher yields. Grain yield in Jefferson, a semidwarf, early season variety, was increased 500 kg/ha by gibberellic acid applied at the beginning of the reproductive phase of growth. Experimental plant growth regulators containing natural and synthetic gibberellins, auxins, and cytokinins
produced yield increases ranging from 0 to 500 kg/ha and had no effect on premature abscisin layer in grain induced by panicle blight (Pseudomonas glumeae). Suboptimal rates of prohexadione-calcium (0.1 kg/ha) reduced mature plant height by 1 to 2 cm with no effect on lodging resistance, maturity, and grain production. In a simulated weed resistance management system with transgenic rice, maleic hydrazide affected seed production on 100% of the panicles of a crop compatible weed substitute. Maleic hydrazide applied during the late grain filling stages of the first crop increased grain yield by 30% in the subsequent ratoon crop.
Impacts
Plant growth regulator use in rice can have a direct, positive impact on crop vigor, weed control, lodging tolerance, and grain production. Also, improving crop growth and development with plant growth regulators facilitates crop management, which decreases production costs and increases overall productivity.
Publications
- Dunand, R.T. et al. 2001. Rice physiology reports. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., LSU Agricultural Center, 92:154-283.
- Dunand, R.T. 2001. Plant growth regulators in rice. Proc. Western Pl. Growth Reg. Soc. 13:57-61.
- Dunand, R.T., Webster, E.P., Linscombe, S.D., and Masson, J.A. 2001. Impact of gibberellic acid on crop tolerance of imidazolinone tolerant rice. Proc. S. Weed Sci. Soc. 54:44.
- Dunand, R.T. 2001. Primo, nitrogen fertility, and stature reduction in rice. Proc. Rice Tech. Wrkg. Group. 28:152.
- Dunand, R. 2001. A comparison of mefluidide and prohexadione-calcium on plant growth and crop production in semidwarf rice. Proc. Pl. Growth Reg. Soc. of Am. 28:64.
- Saichuk, J.K., Dunand, R.T., et al. 2001. Plant growth regulators. In: 2002 Rice Varieties and Management Tips. La. Coop. Extn. Serv. Pub. 2270. 36 pp.
- Linscombe, S.D., Jodari, F., Bollich, P.K., Groth, D.E., White, L.M., Chu, Q.R., and Dunand, R.T. 2001. Registration of `Earl' Rice. Crop Science 41(6):2003-2004.
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Progress 01/01/00 to 12/31/00
Outputs
Growth promotants and retardants were studied for their effects on plant growth and crop production in rice. Gibberellic acid hastened emergence by 3 days, increased seedling population by 25%, and increased seedling height by 5 cm. Response was variety dependent with long-grain varieties more responsive than medium-grain varieties and semidwarf varieties more responsive than tall varieties. Injury from postemergence applications of carfentrazone, halosulfuron, imazethapyr, fenaxoyprop-p-ethyl, and bispyribac reduced seedling height by 2 cm and was not reversed by gibberellic acid. Imazethapyr+gibberellic acid reduced grain yield by 1000 lb/A. Midseason applications of gibberellic acid to selected varieties increased grain yield by 500 lb/A, and commercial plant growth regulator formulations (Auxigro, Burst, Early Harvest, Megazone, and Phyllsyner) had no effect on root and shoot growth and grain yield. Prohexadione-calcium and mefluidide reduced mature plant height
by 10 cm, increased lodging resistance, delayed maturity by 7 days, increased grain moisture by 5%, and reduced grain yield by 1000 lb/A. Boron, calcium, ethylene, gibberellic acid, naphthalene acetic acid, and zinc had no effect on early abscisin during grain formation induced by panicle blight (Pseudomonas glumeae). Ratoon crop growth was initiated one week early by maleic hydrazide applied during the first crop with no impact on yield.
Impacts
Plant growth regulator use in rice can improve crop vigor, aids in weed control, and increases lodging tolerance. Improving crop growth and development facilitates crop management, which decreases production costs and increases productivity.
Publications
- Dunand, R.T. 2000. Gibberellic Acid, Planting Depth, and Command Injury in Rice. Proc. S. Weed Sci. Soc. 53:32.
- Saichuk, J.K., R.T. Dunand, et al. 2000. Plant growth regulators. In: 2001 Rice Varieties and Management Tips. La. Coop. Extn. Serv. Pub. 2270. 36 pp.
- Dunand, R.T. et al. 1999. Rice Physiology Reports. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., LSU Agricultural Center, 91:253-356.
- Dunand, R.T. 2000. Enhancing Lodging Resistance in Rice with Plant Growth Regulators. Proc. Western Pl. Growth Reg. Soc. 12:34-38.
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Progress 01/01/99 to 12/31/99
Outputs
Gibberellic acid (GA), maleic hydrazide (MH), and the growth retardants, prohexadione-calcium and trinexapac-ethyl had effects on growth and development. The growth enhancing plant growth regulators, Early Harvest, Burst, and Cytoplex (proprietary formulations of gibberellins, auxins and cytokinins), Auxigro (gamma aminobutyric acid), and GWN-6001 (a mixture of derivatives of a brassenosteroid and a jasmonic acid) did not affect growth. Emergence and seedling height were increased 25 and 50%, respectively, by GA applied as a seed treatment and seedling spray. The rate of 1 g/A gave optimal responses under warm conditions (daily average temperature ranging between 20 and 30 C), and rates of 2 to 3 g/A were required at successively lower temperatures to optimize response. Grain yield was increased in some varieties by 300 to 500 lb/A with GA applied during the reproductive phase of growth. Deep planting, facilitated by GA seed treatment, did not reduce seedling injury
from a postplant and preemergence herbicide application of clomazone. Rice and soybeans were tolerant to drift rates of MH (less than 0.4 lb/A) applied during susceptible stages of growth. The growth retardants decreased plant height by 3 to 4 inches, improved lodging tolerance, increased tillering by 20% and decreased grain yield by 700 lb/A. The yield reduction was less at high nitrogen fertility. Ethylene, naphthalene acetic acid, aminoethoxyvinylglycine, and 6-benzyladenine applied at heading had no affect on limiting premature termination of grain formation induced by panicle blight (Pseudomonas glumeae). Flight Control (anthroquinone), a bird repellant seed treatment, was compatible with standard fungicide, insecticide and plant growth regulator seed treatments and had no affect on germination, plant density or seedling vigor.
Impacts
Plant growth regulator use in rice can improve crop vigor, aids in weed control, and increases lodging tolerance. Improving crop growth and development facilitates crop management, which decreases production costs and increases productivity.
Publications
- Dunand, R.T. et al. 1998. Rice Physiology Reports. Ann. Res. Rpt., Rice Res. Stn., La. Agri. Exp. Stn., LSU Agricultural Center, 90:194-347.
- Dunand, R.T. 1999. Influence of environment and gibberellic acid seed treatment on seedling vigor of water-seeded rice. Proc. Western Pl. Growth Reg. Soc. 11:53-57.
- Dunand, R.T. 1999. Rice tolerance to maleic hydrazide used in red rice suppression. Proc. S. Weed Sci. Soc. 52:49.
- Dunand, R.T. 1999. Sensitivity of rice to low rates of maleic hydrazide. Pl. Growth Reg. Soc. of Am. Quarterly. 27(2):48.
- Dunand, R.T. 1999. Sensitivity of rice to low rates of maleic hydrazide. Proc. Pl. Growth Reg. Soc. of Am. 26:184.
- Dunand, R.T. 1999. Effects of preheading applications of gibberellic acid on rice growth and production. Proc. Rice Tech. Wrkg. Grp. 27:211.
- Bollich, P.K. and R.T. Dunand. 1999. Gibberellic acid use in stale seed bed rice production. J.E. Hook (ed.) Proc. 22nd Ann. South. Conservation Tillage Conf. for Sustainable Agriculture. Tifton, GA. 6-8 July 1999. Georgia Agriculture Experiment Station Special Publication 95. Athens, GA. p. 99-103.
- Saichuk, J.K., R.T. Dunand et al. 1999. Plant growth regulators. In: 2000 Rice Varieties and Management Tips. La. Coop. Extn. Serv. Pub. 2270. 34 pp.
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