Effect of time and level of detopping on grain and fodder yield and quality of maize (Zea mays L.) tops in Eastern Hararghe

Field experiment was carried out during 2001 cropping season under rain-fed at Raree Research Center of Alemaya University with the objectives to investigate the effects of time and level of detopping on grain yield, yield components, green fodder yield and quality of maize tops. Factorial combination of four times of detopping (15, 30, 45 and 60 days after 50% silking) and four levels of detopping (25%, 50%, 75% and 100%) of maize (var. Rare-1) with a check were laid out in randomized complete block design in triplicate. Grain yield, yield components, green fodder yield and nutritive value of maize tops were studied. The ANOVA showed significant differences due to time of detopping for most parameters. On the other hand, level of detopping did not affect most of the parameters except stover yield. As compared to detopping at 30 days after silking, detopping at 15 days after silking reduced the grain yields significantly. Besides, ear length and number of kernels/row were also reduced due to detopping at 15 days after 50% silking as compared to detopping at 30 days after 50% silking. Days to maturity, ear height, 1000 kernel weight and shelling percent did not differ significantly due to time of detopping. On the contrary, the highest dry matter yields of 13.78 and 13.42 q/ha of maize tops were obtained when maize plants were detopped at 15 and 30 days after 50% silking, respectively. With regard to fodder quality, crude protein and either extract increased while crude fiber and total ash contents decreased as a result of detopping at 15 and 30 days after silking as compared with other treatments. The interaction effects between time and level of detopping were virtually absent except for nitrogen free extract and number of kernel rows/ear. These findings of present investigation indicate that 100 percent detopping of maize (var. Rare-1) at 30 days after 50% silking provide the grain yield with little or no reduction plus maximal fodder yield with highest nutritive values as compared to other level and time of detopping.