Effect of Nitrogen and Water Stress on the Growth, Water Use Efficiency and Seed Yield of Rapeseed (Brassica Napus L.)

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Wamuongo J.W.
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The effects of water stress and nitrogen application to the growth, yield and water use efficiency of rapeseed were investigated in the greenhouse. The parameters measured included plant height, maximum number of leaves on the main stem, number of primary branches per plant, number of pods per branch, number of seeds per. pod, seed yield per plant and amount of water used. All parameters, except for maximum number of leaves on the main stem, were affected by water stress. Application of N fertiliser when water supply was adequate promoted growth of all plant parts and increased seed yield, while application to water-stressed plants suppressed growth and yield. When N was not applied, there was a more conservative use of available water, leading to less dry matter production than when water was not limiting. Application of N appeared to promote water use with the effect being greater in the nonstressed plants. The water-stressed, non-fertilised plants were the most inefficient in water use, requiring about 3300 g of water to produce 1 g dry matter, while the non-stressed plants, regardless of the N fertiliser applied, were about twice as efficient, requiring about 1600 g of water to produce 1 g dry matter. However, these values are still large compared to those obtained under field conditions.
East African Agricultural And Forestry Journal, 61 (No. 2), p. 187-190