Accepted 20th May, 2016
Aridity of the climate, high summer and low winter temperatures, soil salinization and low nutrient contents in soil are among the main causes, which limit productivity of winter wheat in the northern zone of Karakalpakstan. Experiments to study adaptability of the different wheat varieties to the local climatic and soil conditions have been aimed at identifying the best performing, high-yield varieties. Among tested varieties, Polovchanka produced a highest grain yield in both trials under fertilizer application rates of N120P100K60 and N200P120K80. This variety has high values of the photometric leaf surface area (37-39.2 thousand m2 ha-1) and dry matter (9.26 t ha-1). The yield of grain in the experimental site (1.01 t ha-1) was substantially higher compared with that in the control site. The yield of wheat increases due to the higher number of productive crop stems per 1 m2, grain weight per spike and higher weight of 1000 seeds. Compared with the traditionally applied fertilizer rates of N120P100K60, application of N200P120K80 contributed to the increase of all productivity indicators: Leaf surface area increased on the average by 8.3 thousand m2 ha-1. There was a high correlation (R - 0.97) between the increased fertilizer application rates and grain yield.
Keywords: Soil and climatic conditions, mineral fertilizers, productivity, crop leaf area, dry matter, Aral Sea region.