Competition for water and nutrients in mixed stands of spring wheat

Summary Grain yields, moisture extraction pattern, water use efficiency and NPK uptake were studied with three spring wheat cultivars grown in pure and mixed stands under three irrigation levels. The three spring wheat cultivars produced similar grain yields. None of the mixed stands yielded more than pure stands. Soil moisture extraction pattern of the three cultivars and their binary mixed stands was similar from the top layers, however, more moisture was extracted from deeper layers by the tall cultivar C 306 and mixed stands having C 306 as a component cultivar. The water use efficiency of the dwarf cultivar HD 2160 was higher than the other two cultivars. Two mixed stands, namely, 3 : 1 and 1 : 1 Kalyansona: C 306 had a higher water use efficiency than their pure stands but all other mixed stands were intermediate. The grain yield and NP uptake of the dwarf cultivar HD 2160 were less when it was grown in mixed stands, while that of semi-dwarf cultivar Kalyansona and tall cultivar C 306 were more when grown with cultivar HD 2160 than when grown alone or together. The K uptake of all the three cultivars was adversely affected when they were grown in mixed stands. Two or three irrigations increased the moisture extraction from top layers but decreased the water use efficiency as compared to one irrigation. Grain yield and NPK uptake of the cultivars and their binary mixed stands were more with two or three irrigations than with one irrigation.