Forage yield and Quality attributes of sorghum-legumes intercropping Systems under different plantinf times and spatial arrangements

Abstract

Sorghum being a drought and heat resistant crop has the potential to serve as an alternate forage crop in rainfed as well as irrigated tracts. Currently, farmers are obtaining much less forage sorghum yield and that too with sub-optimal quality attributes. Intercropping of forage sorghum with legumes is one of the biologically and economically viable options to increase forage yield and quality. However, for boosting the productivity of sorghum-legumes intercropping systems, planting time and spatial arrangements of component crops need to be optimized. Two field experiments were executed to evaluate the forage yield, quality attributes and profitability of sorghum-legumes intercropping systems under varied planting times and spatial arrangements at the Agronomic research area, University of Agriculture Faisalabad, Pakistan during 2013 and 2014. The first experiment involved forage sorghum (var. Hegari) intercropping with different legumes including cowpea (var. P-518), cluster bean (var. BR-99) and soybean (var. Ajmeri) under different spatial arrangements like 2:1 and 2:2 row proportions of sorghum and legumes along with mixed seeded crop of sorghum and legumes sown in 30 cm spaced rows. The sole crops of sorghum and all of three legumes were sown as control treatments. The experimental design was randomized complete block design (RCBD) with three replications. The experimental variables included forage sorghum yield and yield components, physiological parameters (leaf area index, leaf area duration, crop growth rate and net assimilation rate) of sorghum and quality attributes (crude protein, crude fiber, ether extractable fat and ash) of sorghum, legumes and mixed forage. The result revealed that green forage yield of sorghum and legume intercrops was decreased in intercropping systems as compared to their sole crops. Mixed seeded crop of sorghum and cowpea sown in 30 cm spaced rows outperformed all other intercropping systems in terms of green forage yield as well as quality attributes. Soybean sown either as a sole crop or in intercropping with sorghum gave the lowest green forage yield. However, sorghum and soybean sown in 2:2 row proportions recorded the highest crude protein and ether extractable fat. Thus, mixed seeded crop of sorghum and cowpea sown in 30 cm spaced rows was recorded to be the most productive intercropping system during both years. In the second field experiment, sorghum was intercropped with soybean at the same time, 15 days before soybean and 15 days after soybean under different spatial arrangements including 1:1, 1:2, 2:1 and 2:2 row proportions of sorghum and soybean. The experimental design was randomized complete block design (RCBD) with factorial arrangement and was replicated thrice. Sorghum planted 15 days before soybean in 2:1 row proportion gave the highest green xvi forage yield along with better quality forage. Sorghum sown 15 days after soybean in 2:2 row proportions gave the lowest green forage yield. Overall, sorghum performed much better when it was sown 15 days earlier to soybean and it was followed by sorghum sown with soybean at the same time. Sorghum gave the lowest green forage yield when its sowing was delayed for 15 days after soybean cultivation. Regression analysis depicted a positive relationship between experimental variables and green forage yield of sorghum. In contrast, soybean gave the highest green forage yield when it was sown 15 days before soybean in 2:2 row proportions during both years. To conclude with, sorghum planted 15 days before soybean in 2:1 row proportion appeared to be the most productive and complementary intercropping system as far as green forage yield, quality of mixed forage and economic returns are concerned.