Growth‐Stage‐Based Irrigation Management on Biomass, Yield, and Yield Attributes of Spring Canola in the Southern Great Plains

Abstract

2623 RESEARCHL imited water availability is one of the major constraints to agricultural production in the semiarid US Southern Great Plains (SGP). Erratic rainfall and frequent droughts further aggravate stress on agriculture in the region (McGuire, 2012). The Ogallala aquifer is the main resource for irrigation in SGP (Chaudhuri and Ale, 2014). Excessive use of groundwater for irrigation has significantly depleted the aquifer. A recent study showed that the aquifer lost 31 and 33% of its water storage in New Mexico and Texas, respectively, between the predevelopment period and 2010 (Steward and Allen, 2016). The pumpage rate is greater than the recharge rate, resulting in a decline in water table depth by >30 m in 30 yr in several parts of the SGP including New Mexico and Texas (Sophocleous, 2000). Scanlon et al. (2012) reported that if the current pumping rate continued, 35% of the total irrigated area in the SGP would not be able to irrigate in the next 30 yr. This would have a devastating effect on the rural economy in the region.The major agricultural crops cultivated under irrigation in the region include corn (Zea mays L.) and forage sorghum [Sorghum bicolor (L.) Moench], which have high evapotranspiration (ET) requirements of 772 and 637 mm for their production ABSTRACT Extensive use of groundwater for irrigation has significantly depleted the Ogallala aquifer, threatening the sustainability of irrigated agriculture in the Southern Great Plains. There is a need to identify a low-water-requiring alternative crop and understand the response of that crop to deficit irrigation strategies. The objective of this study was to assess biomass partitioning and yield of spring canola (Brassica napus L.) under deficit irrigation. Three diverse canola cultivars ('H930', 'H955', and 'L140') were grown under four different irrigation treatments; full season irrigation (FI), no irrigation at the vegetative stage (VS), no irrigation at the reproductive stage (RS) and dryland (DL) at Clovis, NM, on Olton clay loam soil. Seed yield of VS was similar to FI in both years but was greater by 93 and 200% in 2015 and by 120 and 263% in 2016 than RS and DL, respectively. Biomass and oil yield of VS were similar to those of FI in 2015 but were lower by 14% in 2016. Relieving water stress with irrigation at flowering increased leaf area index of VS and made it similar to that of FI by pod development stage. Biomass accumulation was greater in treatments receiving irrigation after flowering and most of the post-flowering biomass was partitioned into reproductive parts. Among yield components, greater 1000seed weight in VS than RS and DL, indicated recovery of canola stressed at the vegetative stage. Results indicated that if water is limited, the vegetative growth stage would be a better time to skip irrigation in spring canola.

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Main factors affecting nutrient and water use efficiencies in spring canola in North America: a review of literature and analysis

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