phenological and pomological characteristics of five promised walnut genotypes in karaj, iran

Late spring frost is one of the most important factors causing loss of production of the persian walnut (juglans regia l.). therefore, the selection of spring frost tolerant genotypes has been among the most important priorities in the breeding programs during the recent years in horticultural science research institute, karajiran.  after the spring frost in 2010, five superior genotypes (b10, h1/1, h1/7, h2/1, and h2/12) were selected among 250 walnut genotypes of kamalshar walnut collection in karaj. at the second stage, vegetative and reproductive characteristics (leafing and flowering date, yield, nut and kernel) of the selected genotypes were evaluated and compared with chandler, hartley, pedro, ronde de montignac and franquette in 2010 and 2011. among the genotypes, h2/12 with 534 and 312g/m2 of scaffold cross area of nut and kernel yield showed the maximum production. the h2/1 with 3.37 nut/ cm2 of trunk cross sectional area and h2/12 with 48.1 nut/m2 of scaffold cross area showed the highest crop density. based on this evaluation, the five promised walnut genotypes showed very good performance in comparison with the commercial walnut cultivars.