Optimizing the Planting Date for Onion Production

Abstract

This investigation was carried out during 2018 and 2019 at the research farm of the Agriculture Faculty of Kabul University, Afghanistan to study the correlation between weather conditions (maximum, minimum and mean temperature, relative humidity, cumulative day light and cumulative rainfall) and onion plant growth, yield and bulbs quality, as well as to find the optimal planting date for onion variety Safid e Paisaye. The data was analyzed with STAR software. The results of this study reveal that, increasing temperature and decreasing relative humidity and rainfall during growing season, caused faster maturity of bulbs, produced small sized bulbs, and finally reduced onion bulbs yield. It was observed that, due to relatively lower temperature and higher relative humidity during early growth stages the onion grown early in spring (seed sown in early March and transplants planted early in May) took longer period for maturation, produced larger bulbs and higher yield. This was also noted that due to longer maturation period the onion plants grown in early spring received a higher cumulative heat and sun light which contributed to improve bulbs quality and yield of onion. Based on this study results it is concluded that, early planting date of onion variety Safid e Paisaye not only increased significantly yield but also improved bulbs quality.