29. Intercropping of sweet potato and legumes.
In: AVRDC Progress Report 1990, pp. 240-243; ISSN 0258-3089; AVRDC,
P.O.B. 205, Taipei 10099
This study evaluated different leguminous crops and examined their planting time relative to that of sweet potato to increase the productivity of sweet potato-based intercropping systems.
Two soybean varieties (AGS 66 and AGS 129) one vegetable soybean (AGS 292), one mungbean (VC 3890 A) were intercropped with sweet potato (TN 67) on two relative planting dates.
This trial was carried out in late spring to compare with results from previous trials in different planting seasons and to determine the relationship between environment and agronomic management of these intercrops.
The climatic conditions during this trial was from a dry cool toward a hot-humid season.
Results of light interception clearly indicated that the mungbean canopy developed slowly compared to other crops. Thus, sweet potato growth, in terms of light interception after the legumes' harvest was less affected by mungbean than soybean. Vegetable soybean sown nine days after sweet potato reduced light interception of sweet potato less than that sown on the same days as grain soybean sown at either date.
The results show that there were significant effects of genotypes, and relative planting dates of legumes on sweet potato yield and the combined yield. Planting of legumes nine days after sweet potato transplanting substantially reduced the competition between legumes and sweet potato. Among legumes, mungbean was dominated by sweet potato because of its slow initial growth. Mungbean was more suited for intercropping with sweet potato than other legumes. Results of the combined yield indicated that late planting in spring is not suitable for sweet potato-legume intercropping compared to that in other planting seasons in previous trials.
It can be concluded that sweet potato-legume intercrop performed better in cool dry than in hot wet season. If it is adopted across dry and wet seasons, planting should begin in wet season with maturity in the dry season. To maximize the yield advantage of intercrops, suitable genotypes and appropriate relative planting time should be identified.
Component crops when intercropped usually compete with each other for growth resources such as light, nutrients and water. To minimize this competition and increase production, appropriate cultural practices such as choice of genotypes, plant populations and spatial arrangements and relative planting time should be adopted.
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