Crop design for the doubled up groundnut and pigeonpea intercrop systems
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Amos Ngwira. (26/2/2020). Crop design for the doubled up groundnut and pigeonpea intercrop systems.
Smallholder farmers of eastern and southern Africa practice intercropping to intensify crop production, and mitigate land shortages. Intercropping two grain legumes, groundnut with pigeonpea, a system known as ‘doubled-up legumes’ technology is one of the promising intercropping systems. The current productivity of this intercropping system could be improved by careful selection of varieties that minimize intraspecific competition. Currently, a large number of varieties of both pigeonpea and groundnut with varying plant architecture, growth duration and growth habits are available but knowledge about the productivity of these varieties when grown as intercrops is lacking. A study was conducted to identify groundnut and pigeonpea varieties that optimize resource use efficiency and yield and improve economic returns to smallholder farmers when intercropped. Treatments consisted three varieties each for groundnut and pigeonpea arranged as a factorial structure in a randomized complete block design with three replications. These were assessed at Chitala and Chitedze Research stations, representing low and mid altitude agro-ecological zones, respectively, for two seasons (2016-2018). In general, intercepted radiation and photosynthetic efficiency were greater for groundnut in intercrops with medium and long duration pigeonpea varieties. In the first season, while biomass yields of medium and long maturing groundnut varieties were reduced in intercrops with pigeonpea, yields of short duration variety in intercrops with all the varieties of pigeonpea were comparable to sole crops at Chitedze. Medium duration variety outperformed the other groundnut varieties when grown as sole crop at both sites and during both seasons, with largest increase in grain yield observed during second season at both sites. However, in the second season, medium duration groundnut variety gave 1.40, 0.90 and 1.14 Mg ha-1 less grain yields in intercrops with Mwaiwathualimi, Kachangu and Chitedze1 respectively at Chitala, and 1.20, 0.93 and 0.92 Mg ha-1 less grain yields in intercrops with Mwaiwathualimi, Chitedze1 and Kachangu, respectively at Chitedze compared with sole crops. Short duration groundnut variety in intercrops with pigeonpea of at least medium duration in maturity gave comparable grain yields to sole crops at both sites and during both seasons. Pigeonpea grain yields were not influenced by varieties nor intercrops with groundnut at Chitala during both seasons. In 80% of the cases, CG13 and CG11 gave greater groundnut yields when pigeonpea grain yields were highest, demonstrating complementarity of the two crops in association. Land equivalent ratios (LERs) of all intercrop combinations were greater than unity indicating more efficient and productive use of environmental resources by intercrops. Early maturing groundnut variety in intercrops with late maturing pigeonpea achieved highest pLER ratios of 0.98 and 0.73, respectively. Economic returns and benefit-cost ratios were greater for intercrops than either sole crop. Intercropping short duration groundnut variety, CG13 with at least medium to long duration pigeonpea varieties was the most productive and lucrative system. This suggests that careful selection of varieties in intercrops with different architecture and growth habits are complementary and contribute to the sustainable utilization of limited land resources that enhance resource use efficiency, yield and economic returns.