RESPONSE OF BREAD WHEAT (Triticum aestivum L.) TO IRRIGATION DEPTHS AND NITROGEN RATES AT WERER, RIFT-VALLEY OF ETHIOPIA

Abstract

Management of moisture and soil nitrogen is the most important practice for wheat production in arid and semi-arid regions of the country. A careful combination of water and nitrogen is therefore compulsory to improve the productivity of wheat. A field experiment was conducted at Werer Agricultural Research Center, Amibara district during 2018/19 cropping season to assess the effects of irrigation depths and nitrogen rates on bread wheat. The experiment was laid out in split-plot design with three replications. Three irrigation depths (50, 75 and 100% ETc) were assigned to the main plots whilst, four nitrogen levels (0, 60, 120 and 180 kg ha-1) were assigned to the sub-plots. The analysis of variance revealed that except days to heading, days to maturity, plant height, number of productive tillers, number of kernels per spike, spike length and harvest index, all parameters were significantly (p<0.05) influenced by interaction effect of irrigation depths and nitrogen rates. The maximum grain yield (4523.30 kg ha-1) was recorded in response to 100% ETc and 180 kg N ha-1 whereas, the lowest grain yield (2400.50 kg ha-1) was found from 50% ETc and no nitrogen application. The highest water productivity (WP, 1.01 kg m-3) was recorded from 50% ETc and 120 kg N ha-1 while, the lowest water productivity ( WP, 0.50 kg m-3) was found from 100% ETc and no nitrogen application. The present study also showed that the highest agronomic efficiency (11.43 kg grain kg-1) was recorded from 100% ETc and 60 kg N ha-1 while, the lowest AE (3.05 kg grain kg-1) was obtained from 50% ETc and 180 kg N ha-1. Based on economic analysis, the highest net benefit (49,667.76 ETB ha-1) was obtained from application of 100% ETc and 180 kg N ha-1 while, the lowest net benefit (21,754.36 ETB ha-1) was resulted from 50% ETc and no nitrogen application. From the present study it can be concluded that the integration of 100% ETc with 180 kg N ha-1 attained the maximum grain yield and highest net return compared to other combinations. Therefore, growers in the study site are suggested to apply 100% ETc combined with 180 kg N ha-1. However, when water scarcity is high, 75% ETc alongside with 180 kg N ha-1 appears to be a promising integration level since, it resulted relatively higher grain yield (3840.90 kg ha-1) and reasonable net return of (36,795.16 ETB ha-1).