Effect of Thermal Indices on Yield of Garlic (Allium sativum L.) Varieties under Variable Weather Conditions of South Saurastra Agro-climatic Zone of Gujarat, India

A field experiment was conducted during Rabi (spring) season of year 2017-2018 at Junagadh Agricultural University, Junagadh, Gujarat, India. Four varieties of Garlic (GG-4, GJG-5, Promising and Local variety) were sown on four different dates for generating different weather condition during various phenological stages of crop. Results revealed that sowing between 7th to 21st November produced significantly higher growth due to fulfillment of optimum thermal requirement for various plant processes. Timely sown garlic crop recorded significantly higher GDD (growing degree days), HTU (helio-thermal units) and PTU (photo-thermal units) and HTU (Heat use efficiency). Delay in sowing (after 21st November) reduced the crop duration and yield. Yield had higher value in local variety followed by GG-4and GJG-5 in all weather conditions. Yield was more in timely sown crop as compared to late and very late sown crop. Local variety was found more conducive for growth and higher thermal unit.