Irrigation and Plant Spacing Effects on Seed Production of Buffalo and Coyote Gourds

Abstract

AbstractBuffalo gourd (Cucurbita foefidissima HBK) and coyote gourd (Cucurbita digitata Gray) are xerophytic perennial cucurbits with potential as oilseed or starch crops for arid and semiarid lands. This study investigated irrigation and plant spacing effects on growth, water requirements, and oilseed production of these species. Irrigation of first‐season buffalo gourds planted in 1981 at a 610‐m elevation site on Pima clay loam [fine‐silty, mixed (calcareous) thermic Typic Torrifluvent], and irrigation and plant spacing were evaluated on first‐season buffalo and coyote gourds at a 360‐m site in 1983 on Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid) and Trix clay‐clay loam [fine‐loamy, mixed (calcareous), hyperthermic Typic Torrifluvent], respectively. Irrigation and plant spacing were evaluated on second‐season buffalo gourds planted in 1983. Irrigation did not affect first‐season buffalo gourd yields. Second‐season yields were reduced by irrigating when the available soil water was 75% depleted (I2) compared to irrigating when soil water was 50% depleted (I1). Coyote gourd yields were reduced by the I2 treatment in 1983 but not in 1984. Consumptive water use for first season buffalo gourds in the I1 treatment at the 610‐ and 360‐m sites was 870 and 645 mm, respectively. Consumptive water use was similar for coyote and buffalo gourds at the 360‐m site. In the first season, these species derived up to 50% of water used from the top 0.4 m of soil, and extracted water to a depth of at least 2.6 m. Irrigation did not affect water‐use efficiency (WUE) of either species. Buffalo gourds had higher WUE in the second season (0.09 kg seed m−3 water) than the first season (0.04 kg m−3). Plant spacings of 0.25 to 2 m in 1‐m spaced rows had no effect on first‐season yield in 1983, but in 1984 a quadratic relationship indicated that the closest and widest spacings reduced yields. Coyote gourd consistently outyielded buffalo gourd at the 360‐m site. Although these gourd species have promising water use characteristics for arid lands agriculture, the low seed yields of the cultivars currently available appear to limit their potential as oilseed crops.