Effect of Green Gram-sorghum Intercrop Arrangement on Crop Growth, Yield and Resource Use Efficiency in Southeastern Kenya

Abstract

Small scale farmers in dryland areas generally grow green gram under sole crop system. However, this system has produced low yields per unit area of land and failed to meet the growing population’s demand despite the development of improved green gram varieties. Plant arrangement patterns and microclimate manipulation have been studied on monocropping system and found to affect crop growth and yield. Further, there is lack of information on plant arrangement pattern that farmers can adopt under sorghum-green gram intercropping in southeastern Kenya that could give higher yields. Experiments were conducted simultaneously during the 2022 short rains season in two dryland locations to (1) evaluate the effect of intercropping intimacy on the growth and yield of green gram and sorghum, and (2) determine the effect of sorghum-green gram intercropping intimacy on crop microclimate and resource use efficiency. Intercropping arrangements were double alternate rows of sorghum and green gram (double row) and single alternate rows of sorghum and green gram (single row) as well as control of both sole crop green gram and sorghum. Four green gram varieties including N26, Biashara, Karembo, and KS20 were intercropped with sorghum variety Seredo. Treatments were placed in a randomized complete block design with a split-plot arrangement where crop arrangement system formed the main plots while the green gram variety assumed the subplots and replicated three times. Key measurements were crop growth traits, yield components, resources use efficiency, and intercropping system efficiency. Data were subjected to analysis of variance using R software and treatment means separated by Fisher’s least significant difference at 5% probability. Crops grown in pure stands out-yielded both intercrop crops. Sole green gram recorded the highest yield of green gram with 0.9 t ha-1 the same way sole sorghum recorded the highest yield of 2.7 t ha-1. The key attributes to be focused for intercropping in green gram were crop growth rate, number of seeds pod-1 and pods m-2 while for sorghum were crop growth rate, seed weight, and panicle length due to their positive interrelationships with grain yield. A yield decline of 17.4% was measured under double row while single row reduced yield by 31.9%. The highest green gram yield was obtained in N26 with 1.0 t ha-1 although Biashara recorded higher seed weight than N26 by 29.4% and the lowest vapor pressure deficit (VPD) of 1.3 kPa. However, among the intercropping systems, plants were taller in single rows by 10% compared with double rows, but reduced grain yield by 0.31 t ha-1 compared with the sole crop. Variety N26 recorded the lowest canopy temperature of 19.3 oC and soil temperature of 21.7 oC under the intercropped system...