Irrigation Water Management for Guar Seed Production
1988
Alexander, W. L. | Bucks, D. A. | Backhaus, R. A.
Agricultural crops with low water requirements and drought tolerance are needed for semiarid irrigation regions. Guar [Cyamopsis tetragonoloba (L.) Taub.] is promising as a crop for producing foodthickening agents and fluid additives for the oil drilling industry. The effects of irrigation timing, cultivar, and plant population on water use, growth, and yield of guar were investigated at Maricopa, AZ, on a Mohall sandy loam soil (fine-loamy, mixed, hyperthermic Typic Haplargid) with a water salinity of 1.1 dS m⁻¹ total dissolved salts over a 2-yr period. Variables were: six irrigation levels (one to four irrigations based on physiological plant growth stages), three cultivars (‘Kinman’, ‘Santa Cruz’, and ‘Lewis’), and three populations (78, 26, and 13 plants m⁻²). Three post-establishment irrigations—one before flowering, one during initial pod development, and one at mid-pod filling—were optimal. Four irrigations maximized vegetative growth but reduced seed production per unit of water use; two irrigations lowered growth, seed yield, and water use efficiency. Seed yields averaged 1567, 1650, and 1830 kg ha⁻¹ for Kinman, Santa Cruz, and Lewis, respectively. Seasonal evapotranspiration was 400 mm on the optimal seed production treatments, and water use efficiencies were as high as 0.64 kg seed m⁻³ in 1983, and 0.41 kg seed m⁻³ in 1984. The newer Lewis has the potential for higher yields, in addition to being an attractive, low water-use summer crop for the southwestern United States. Contribution of the Mountain States Area, USDA-ARS, U.S. Water Conservation Lab., Phoenix, AZ.
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