Planting date effects on growth, development and yield of selected agronomic crops at Makhathini Irrigation Scheme.

Abstract

Agriculture, as a source of rural livelihood, is currently faced with challenges such as increasing temperatures, floods, and drought frequency associated with climate change and variability. Climate change is associated with shifting rainfall patterns and distribution, thereby affecting the conventional planting dates. Seasonal variability of rainfall, through uneven distribution and variable amounts, places subsistence farmers at greater risk as they are unable to cope. Simple decision making strategies such as choice of planting date and crop selection could help farmers mitigate some of these impacts. Therefore, the objective of this study was to evaluate the effect of planting date selection on growth and yield of three crops, namely, maize (cereal), dry beans (legume) and sweet potato (root crop). Four planting dates were selected starting from November, 2013 through to February, 2014 and field trials were established at Makhathini Research Station, Northern KwaZulu-Natal. The choice of planting date significantly impacted on growth and yield of crops, especially during critical developmental stages where crops needed sufficient water and optimum temperatures. Dry mass accumulation was greater in the first planting date followed by the third planting date and lastly the second planting date. Water and heat stress were not the only climate characteristics affecting crop growth and yield of all the crops. Flash floods led to significant yield losses, and in some cases, crop failure. Based on the results, planting date selection can be used as a management tool for managing water stress under rainfed conditions. Optimal planting dates varied for the different crops. Maize performed better in the first and third planting dates. Sweet potato was successful only in the second planting date although there were no marketable storage roots. Sweet potato showed high sensitivity to water stress and high temperatures particularly during early establishment and vegetative phases. Dry beans performed better during the fourth planting date. The findings suggest that the crops can be planted at different times of the season. This can improve household food security through broadening on-farm diversity and spreading the risk of crop failure.