Irrigation Effects on Water Use, and Production of Tap Roots and Starch of Buffalo Gourd
1989
Nelson, J. M. | Scheerens, J. C. | Bucks, D. A. | Berry, J. W.
The buffalo gourd (Cucurbita foetidissima HBK) is a possible new root starch crop for semiarid regions. Information on water use relationships of this species is needed to determine its suitability for arid lands agriculture. The objective of this study was to assess the influence of water management on buffalo gourd tap root production and water use. Five irrigation levels were evaluated for an annual buffalo gourd crop in 1985 and 1986 at a 360-m elevation field site on Casa Grande sandy loam (fine-loamy, mixed, hyperthermic Typic Natrargid) using plant populations of 400 000 to 450 000 plants ha⁻¹. Irrigating at 50% available soil water (ASW) content (I₁) gave higher fresh tap root yields than irrigating at 75% ASW (I₂) (27.8 vs. 24.1 Mg ha⁻¹) in 1985 with identical starch yields. In 1986 the I₂ treatment was higher than the I₁ treatment in starch yield (3.1 vs. 2.1 Mg ha⁻¹) and tap root starch concentration (47.5 vs. 38.1%). Vines of water stressed plants (I₂) grew rapidly when irrigated. Consumptive water use was 649 and 487 mm in I₁ and I₂, respectively. Peak consumptive use rates were <6.5 mm d⁻¹. As much as 48% of seasonal water use was from the 0 to 0.4 m soil depth. Water was extracted to a depth of 2.6 m. The I₂ treatment had the highest wateruse efficiency (WUE), 4.9 kg m⁻³, for fresh root production. The WUE for starch production was higher for the I₂ treatment (0.62 kg m⁻³) than the I] treatment (0.42 kg m⁻³). Irrigation scheduling to provide moderate stress reduces buffalo gourd water use without reducing starch yield, increasing its potential as a semiarid starch crop. Contribution from the Arizona Agric. Exp. Stn. Journal Paper no. 5005.
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