EFFECTS OF TEMPORARY WATER-STRESS BEFORE ANTHESIS ON GROWTH, DEVELOPMENT AND GRAIN-YIELD OF SPRING WHEAT

Soil water availability can limit grain yields of spring wheat in humi d climates. The objective of this study was to quantify the effect of temporary water shortage at three stages during the development, i.e. stem elongation to flag leaf stage (WS1), flag leaf stage to ear emerg ence (WS2) and ear emergence to anthesis (WS3) on the growth, developm ent and grain yield of spring wheat with special emphasis on the inter action between cultivars and nitrogen treatments. A pot experiment wit h controlled water supply and rain shelters was conducted in 1984 and 1985 in Kiel, NW Germany. The largest relative effect of a temporary w ater stress on crop development occurred after the first treatment per iod, EC 31 to 39 (Zadoks scale). Fresh weight, dry weight and the numb er of tillers per plant as well as the apex length of the second categ ory tillers were reduced compared with the untreated control. After re watering, the differences diminished and eventually plants which were subjected to the WS1 treatment produced more tillers than the control. The largest yield decrease, associated with a reduced number of kerne ls per ear, was observed after the WS3 treatment. The two other treatm ents caused a yield increase due to a compensatory increase in the num ber of kernels per ear in the second category tillers. Additional nitr ogen partly compensated for the effect of a temporary water shortage a t WS1 or WS2 by increasing the single ear yield of the second category shoots.