Kian is the First Drought-Tolerant Rice Cultivar in Iran Developed Through Mutation of Local Varieties

Iranian local rice cultivars have excellent cooking quality but unfortunately, are sensitive to water stress. In the present study, we tried to introduce a drought-tolerant variety using mutation by radiation. The first step was the determining the optimal dose of gamma radiation for the Tarom variety (230 Gy) to obtain a mutant population. Selection was based on drought stress tolerance and other agronomic traits, including plant height, panicle length, number of filled grains per panicle, percentage of fertility, 1000-grain weight, and grain yield from 2009 to 2012. This process led to the identification of 56 promising drought-tolerant mutant lines. Based on preliminary evaluations conducted over two years (2012 and 2013) under both normal and drought stress conditions, 14 lines were selected. The stability of these 14 mutant lines was further assessed in three regions-Rasht, Chaparsar, and Fars-from 2014 to 2015. After the evaluation, the Kian variety was chosen as the superior line for yield, drought stress tolerance, early maturity, and good cooking quality. Agronomic tests determined that applying 90 kg of nitrogen per hectare with a planting distance of 20×20 cm was optimal for this variety. In 2017, Kian was cultivated alongside Hashemi, the check cultivar, in three cities of Guilan province. Results showed that the average grain yield of the Kian variety was 5383 kg/ha under normal conditions and 4093 kg/ha under drought stress, compared to an average yield of 3900 kg/ha for the Hashemi cultivar under normal conditions. The growth period from sowing to maturity ranged from 99-109 days for Kian, while it was 112-114 days for Hashemi.