Effect of Some Climatic Factors on Sweet Potato Yield

Abstract

Field experiment was conducted to evaluate the importance of air temperature, solar radiation and precipitation on root yield and yield components of sweet potato, and to identify optimum planting dates for the different sweet potato varieties, Tainung 66, CN1108-13 and CN1345-8. Planting was done year-round, expect June and July, commencing on 15 January and at 10-day intervals thereafter. The results showed that temperature had significant effects on root size, number of roots/plant and plant survival rate; whereas, solar radiation had a positive relationship with root size only. Precipitation showed a significant effect on root size and number of roots/plant. Multiple nonlinear regression analysis indicated that 81% of the total variation in yield was explained by the variation in the three climatic factors. In general the optimum planting date for the crop was between 16 and 26 March. Planting the crop during this period subjected the plants to cool weather in March and early April during its root formation stage, and to warm weather in late April and May during their root enlargement stage. This climatic condition enhanced root formation and stimulated root enlargement resulting in high yield.