Drought tolerance selection of sugarbeet hybrids

Abstract

Increased water demands and drought have resulted in a need to indentify crop hybrids that are drought tolerant, requiring less irrigation to sustain yields. This study was conducted to assess differences in drought tolerance among a group of genetically diverse sugarbeet hybrids. The study was conducted over three consecutive growing seasons (2008-2010) at the USDA Northwest Irrigation and Soils Research Laboratory in Kimberly, Idaho on a Portneuf silt loam soil (coarse-silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid). Drought tolerance was evaluated by measuring sucrose yield production of six breeding hybrids of Klein Wanzlebener Saatzucht (KWS SAAT AG) and one commercial hybrid (Betaseed Inc.) under six water input treatments. Hybrid drought tolerance was evaluated by linear regression analysis (slope and intercept) of yield versus water input, calculation of a drought stress index (DSI), and comparison of yield potential under full irrigation. The water input treatments were based on a percentage of estimated crop evapoatransipration (ETc). Water input treatments were 125% ETc (W1), 100% ETc (W2), 75% ETc (W3), 50% ETc (W4), 25% ETc (W5) and rain-fed (W6). Irrigation was applied three times a week to meet the desgnated rate. There were significant differences in overall yield potential and in the sucrose yield response to water among hybrids. Greater drought tolerance or greater difference in sucrose yield between hybrids was seen at the lowest water input treatment (intercept difference). Greater drought tolerance was observed for the KWS-05 hybrids compared to the commercial hybrid. Based on these results there exist genetic diversity among existing sugarbeet breeding hybrids.