1. Comparing Water Use Pattern of Winter Canola and Winter Wheat and Their Water Use and Yield Relationships.

Interest in Winter Canola (WC) as an alternative oilseed crop in the Southern High Plains is steadily increasing. The potential benefits of WC in the rotation include source of high quality oil for human consumption, potential feedstock for biodiesel industry, protein rich meal source for dairy animals, and good rotational crop to control weed problems in predominantly winter wheat (WW) rotation. Field trials were conducted at Agricultural Science Center at Clovis, NM in 2008-09, 2009-10 and 2010-11 seasons to compare growth, water use patterns and its relation to yield of WC (cv. Rally and DKW-41-10) compared with WW (cv. TAM-111). Six levels of irrigation ranging from rainfed (only irrigated to establish the crop) to about 25% higher than the estimated evapotranspiration of winter wheat were used in the study. Each plot was irrigated with surface drip system with water meters to measure the exact amount of water applied. Neutron tubes were installed in WW cv. TAM111 and WC cv. Rally and in treatments 0, 50 and 100% ET. Water extraction patterns differed significantly between WC and WW. Generally, WW started extracting soil moisture earlier compared to WC. In response to water stress, WC extracted soil moisture similar to WW by the harvest time. If irrigated regularly (at higher end of irrigation), WC relied on irrigation water more than deep soil moisture. Biomass production by WC and WW responded linearly to water use and there was no difference between WC and WW in two out of three years. Winter canola exhibited excellent recovery from late spring frost that killed most of the regrowth early in the spring. Water use and seed yield were linearly related in both WC and WW, although the slope of WC was lower than WW. However, the relationship in WC was more strongly related on weather conditions during regrowth and flowering period than in WW. Earlier maturing WC seems to be more sensitive to weather extremes than later maturing WC. Rally performed better under the High Plains conditions. Harvest index, was more stable in winter canola across irrigation regimes. Seed oil content ranged from 39 to 42 per cent, lower numbers reported from the drier treatments.  Change in oil content by irrigation regimes was relatively smaller compared to seed yield. Results from all years along with soil moisture data will be summarized in the presentation.