Exogenous Application of Glycinebetaine Facilitates Maize (Zea mays L.) Growth under Water Deficit Conditions
K. Raja Reddy *
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
W. Brien Henry
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
Ramdeo Seepaul
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
Suresh Lokhande
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
Bandara Gajanayake
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
David Brand
Department of Plant and Soil Sciences, Mississippi State University, Box 9555, Mississippi State, MS 39762, USA.
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine whether the exogenous application of glycinebetaine (GB) can ameliorate the effects of water deficit on maize growth and physiological processes.
Study Design: Split plot design with water deficit being the main plot factor and GB application being the subplot factor. Treatment was a combination of water deficit level and GB application with 3 replications.
Place and Duration of Study: R.R. Foil Plant Science Research Center, Mississippi State University, Mississippi State, MS, USA between May and July 2010.
Methodology: A pot experiment was conducted using 31-d old ‘TV25R19’ maize irrigated with 750 ml pot-1 day-1 (WW: well-watered), 450 mL pot-1day-1 (WD60, 60% of WW) and 300 mL pot-1day-1 (WD40, 40% of WW) grown with or without GB application at each stress level. GB was applied as a foliar spray every 5 days at a rate of 4 kg ha-1. Soil moisture content and leaf water potential, growth, biomass, and gas exchange parameters were measured in response to the treatment variables.
Results: Significant GB and water deficit main effects were observed for plant height (PH), leaf dry weight (LDW), ear dry weight (EDW) and total dry weight (TDW) (P £ 0.05) while GB main effects alone were observed for node number (NN) and stem dry weight (SDW) (P £ 0.05). GB application increased leaf area (LA) (5,454 cm2 plant-1) in WD60 plants relative to untreated plants. No GB effect was seen under other treatment combinations at 10 or 20 days after treatment (DAT) measurements. GB did not increase stomatal conductance or transpiration at 10 or 20 DAT in plants subjected to water deficit. GB application resulted in leaf water potential values in the WD60 treatment that were statistically similar to the well-watered plants. Volumetric soil water content did not change with foliar GB application across water deficit treatments except under mild stress after 18 DAT, where soil moisture was higher for GB treated plants.
Conclusion: GB’s effect was most evident in plants from the WD60 treatment. GB application significantly improved PH, LA, LDW, SDW, EDW and TDW and did not influence NN under WD60 conditions.
Keywords: Maize, glycinebetaine, water deficits, growth, development, photosynthesis, pigments.