RESPONSE OF BARLEY (Hordeum vulgare L.) VARIETIES TO SEED AND NITROGEN RATES IN KENYA

Abstract

There is difficulty in attaining malt grade barley since barley varieties recommended for malting must meet specific quality requirements and these demand specific agronomic practices. A study to develop appropriate agronomic packages with reference to cultivar choice, plant population density and nitrogen fertilizer rates for malting Barley was conducted in two barley growing sites, University of Eldoret farm and Mau Narok in Kenya. Three varieties; HKBL 1512-5, HKBL 1385-13 and Nguzo were combined in a 4*3*3 factorial arrangement, in a completely randomized block design (RCBD), with seed rates of 150, 200 and 250 pure germinating seeds m-2 and nitrogen fertilizer rates of 0, 30, 40 and 50 kg-N ha-1 in an experiment at each of the sites to determine the effect of seed and nitrogen fertilizer application rates on their malting quality. Grain yield components including, plant establishment, spike length, number of grains per spike, number of tillers, 1000-grain weight and grain yield; and grain quality components including grain size and grain N-content were recorded. The generated data was subjected to ANOVA using the SAS package. Mean differences were determined by Least Significant Differences; (LSD) at α = 0.05 probability level. Test variety HKBL 1385-13 had superior grain yield than the control variety Nguzo at both the Mau Narok and University of Eldoret sites by 500 kg ha-1 (25%) and 1400 kg ha-1 (37.8%) respectively. It also had a higher number of productive tillers than the control at the UoE site, a factor that could have made it produce superior grain yields. Although test variety HKBL 1512-5 had significantly higher grain yields than the control variety Nguzo at the Mau Narok site by 400 kg ha-1, it had inferior yields at the UoE site. It also had shorter spike length and a lower number of grains spike-1. However, it had consistently heavier grains throughout the study. Test varieties HKBL 1512-5 (2.33% N) and HKBL 1385-13 (2.21% N) accumulated grain N-content beyond the acceptable level of 2.2% N at the Mau Narok site compared to 1.97% N and 1.87% N respectively at the UoE site. Although site differences were observed for the proportion of maltable grains, all test varieties produced acceptable proportions of more than 90 %. Increasing seed rate increased grain yield as expected. However, whereas higher seed rate (250 seed m-2) at Mau Narok produced significant increase in yield by 500 kg ha-1 (11.4 %) over the control seed rate, a similar increase in seed rate at the UoE did not. This is closely related to the effect of increasing seed rate on the grain N-content. Lower seed rates produced grains with higher N-content than the acceptable level for malting of 2.2 % at the Mau Narok site. Whereas N-addition significantly increased grain yield at both sites, it led to accumulation of grain N-content beyond the acceptable level. Test variety, HKBL 1385-13 can be suitable for both sites, but its seed rate should be higher than the control to attain acceptable grain N-content. The superior grain size of test variety HKBL 1512-5 can be used to improve barley varieties with superior yields but with inferior kernel size. Nitrogen fertilizer should be used sparingly with introduced varieties or combined with higher seed rates at the Mau Narok site to retain acceptable grain N-content. These findings confirm that malting barley requires specific site, variety, seed rate and N-rate recommendations.