Application of mungbean residue as green manure. III. Effects on some quality characteristics of sweet potato

Incorporating green manure in soil increases the availability of nutrient elements and improve of quality characteristics in the succeeding crops. So, a field experiment was conducted at the experimental farm and laboratory of Institute of Sustainable Agrotechnology, Universiti Malaysia Perlis, Padang Besar, Perlis, Malaysia. This study was about effect of green manure with mungbean (Vigna radiata L.) on some quality characteristics of sweet potato under two grown conditions; open field and greenhouse. The green manuring of mungbean was compared with the control. Results of the study show of that there were different effect of treatments on quality characteristics of sweet potato. The highest nitrogen content in leaves and protein content in tuberous root 1.64% and 2.49%, respectively, were observed in the treatment of mungbean residue. But the highest sugar content of 19.93% in tuberous root was recorded in control treatment. Mungbean residue and control treatment were not significantly different between them in phosphorous and potassium content in leaves, hardness of tuberous root and starch content. There was significant increment in nitrogen and potassium contents in sweet potato leaves under open field condition. On the other hand, there was significant increment in sugar content under greenhouse condition. But the different conditions were at par in phosphorous content in leaves, starch content in tuberous root and hardness of tuberous root. The nitrogen content in leaves was greatest at treatment of mungbean residue under open field condition, while treatment of mungbean residue under greenhouse condition gave highest protein content in tuberous root compared to other treatments. Highest starch content and sugar in tuberous root were found in control treatment under greenhouse condition 52.90% and 20.92%, respectively.