Growth, dry-matter partitioning and yiel of sweet potato (Ipomoea batatas L.) as influenced by soil mechanical impedance and mineral nutrition under different irrigation regimes.

Abstract

Sweet potato plants were grown under different irrigation regimes ranging from IW/CPE ratio 1.5, 1.2, 0.9, 0.6, 0.3 as well as rainfed control. At lower irrigation level, mechanical resistance of soil restricted tuber bulking as well as significantly reduced tuber yield (r= -0.8712*). Irrigation increased uptake of both N and K compared to rainfed control. While at lower irrigation more soil resistance restricted growth and tuber development, at higher irrigation more labile N as well as K favored more vegetative growth reducing tuber dry matter production and tuber yield. However, the higher uptake of both N and K was observed at IW/CPE ratio 0.9, which also showed highest yield. The significant association of both dry matter production rate (r= 0.9586**) and total biomass (0,9820**) and non-significant association of harvest index (r= 0.6956) with tuber yield suggested more importance of dry-matter production than partitioning of dry matter in determining tuber yield in sweet potato under different moisture regime.