The forage and grain yield of cold-tolerant sorghum and maize as affected by time of planting in the highlands of Kenya.

Abstract

In trials with sorghum and maize in the highlands of Kenya the effects of sowing date on the forage and grain yields were studied. Yields were regressed on sowing date in days after the start of the wet season, mean air temp. during the 1st 5 wk post-em. and sowing date index in a yield stability analysis. Grain yields varied more than total DM yields, indicating that correct sowing date was more important if crops were harvested for grain than for forage. Sorghum cv. E 1291 gave the highest grain yields and sorghum cv. E 6518 the highest DM yields under all conditions. The grain yield of E 1291 was less affected by delayed sowing than the grain yield of maize cv. H 613. In a dry yr delayed sowing was beneficial because it allowed a certain soil moisture reserve to be built up, but this beneficial effect disappeared if the duration of crop development exceeded the length of the wet season. If rainfall was heavy immediately after the dry season, delayed sowing had a pronounced negative effect on yields. Under such conditions DM yields decreased by 1.0 t/ha for each wk delay in sowing for both E 6518 and H 613; grain yields decreased by 0.41 t/ha wk and 0.47 t/ha wk for E 1291 and H 613, resp. All grain yields were positively correlated with av. mean air temp. and regression coeff. varied from 0.77 to 3.67 t/ deg C, but temp was confounded with rainfall and more work was needed to separate temp. and rainfall effects. (Abstract retrieved from CAB Abstracts by CABI’s permission)