Water Stress Effects on Winter Canola Growth and Yield
2010
Tesfamariam, Eyob H. | Annandale, John G. | Steyn, Joachim M.
Canola (Brassica napus L.) is seen as a dryland crop in many parts of the world. In South Africa, there is growing interest in producing canola under irrigation because of its profitability and beneficial disease control characteristics in a rotation system. The objectives of this study were to identify the growth stage most sensitive to water stress and to determine the effect of water stress on crop growth, phenology, seed and oil yield, water use, and seed oil content. A well watered control was compared with treatments stressed during one of the following stages: vegetative, flowering, or seed filling in replicated field studies during 2002 and 2003 at Pretoria, South Africa. Water stress imposed during flowering delayed maturity by 114 growing degree days. In contrast, water stress imposed during seed fill resulted in 127 growing degree days earlier maturity. The well watered control gave the highest value for leaf area index of 8, water use of 709 mm, seed yield of 3831 kg ha⁻¹, and seed oil content of 398 g kg⁻¹ Canola stressed at flowering gave the lowest values for seed yield of 1361 kg ha⁻¹, seed oil content of 340 g kg⁻¹, and water use of 332 mm. Dry matter production per unit water use at seed filling was only a third of its value during the vegetative and flowering stages. Canola seed and oil yield are most sensitive to water stress at flowering and less sensitive during the vegetative and seed-filling stages.
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