Growth of spring canola (Brassica napus) under deficit irrigation in Western Nebraska

Abstract

Drought is a periodic occurrence in the High Plains of the U.S.A.; thereby low-water using crops are desired. Canola, a biofuel and food oil, has been studied in the region under rain-fed conditions for several years. The study's objective was to measure plant growth, seed yield, and oil characteristic of canola at four levels of applied water in western Nebraska. The cultivar Hyola 357 Magnum was exposed to rain-fed only (RF), and irrigated with 10 (LI), 20 (MI), and 30 (HI) cm water. Adding irrigation increased plant growth, i.e., canopy height, stem length, and canopy weight. Highest canopy height (>100cm for MI and HI) was reached by 10 weeks after planting (WAP) with a total of 23cm of applied water or 13cm of irrigation. By 8 WAP, canopy fresh weight was increased by 37 to 58% by MI and HI irrigations. Pod fresh and dry weights at harvest (13 WAP) were increased >50% and >20%, respectively, by all irrigations. Seed yield were increased by each incremental increase in irrigation from 1220kg/ha for RF to 2905 for HI, a 2.4-fold increase. Seed oil content was increased by MI and HI irrigations (4–8%). The fatty acid profile was not substantially altered by irrigation. There was a slight decrease of palmitic acid and increase in linolenic acid with HI. Canola showed that >20cm of applied water is needed for good vine and pod growth but >40cm was needed to achieve the highest yield. Canola could be grown successfully in western Nebraska, supplying oil for fuel and cooking.