jamal, a new persian walnut cultivar for moderate-cold areas of iran

most of walnut production in iran comes from seed originated trees with low quality and quantity as product. for breeding new cultivar(s), from 1983 selection of iranian walnut germplasm was started at seed and plant improvement institute and at the first phase 117 genotypes were collected. seedlings of these genotypes were planted in kamalshahr (karaj), torogh, kahriz and bastam horticultural research stations and evaluations were done for five years. in karaj, genotype z63 was selected together with six other promising genotypes. these seven genotypes and eight foreign walnut cultivars were evaluated for 15 years. results showed that z63 was the best among the native selected promising genotypes. the tree has medium vigor, spreading habit, low shoot density and early- medium leafing time. z63 is a protandrous genotype, so for commercial production it needs a pollinizer cultivar. pistillate flowering period was medium and the pollen shading period was early. fruit and kernel weight and kernel percent was 11.41 g, 5.8 g and 50.77 %, respectively. the minimum planting distance for this genotype is about 7×7m and its yield varied from 500 kg in 5th year to 4 tha-1 at the maturity. fruit shape is long elliptic with smooth shell texture. it has relatively low susceptibility to winter frosts and chilling requirements of terminal and lateral buds and catkins were estimated 750, 900 and 650 hours. growth degree hour (gdh) of terminal and lateral buds and catkins were 14636,15186 and 9071 respectively. pistillate flower abscission (pfa) of this genotype showed to be very low. susceptibility to anthracnose (gnomonia leptostyla) was also very low. the leaves of this genotype was susceptible to bacterial blight (xanthomonas compestris), but after infection most of leaves abscised that helps to reject the infection. unriped fruits of this genotype had the highest resistance among the evaluated cultivars and genotypes. long term evaluation of this genotype together with other native promising and foreign cultivars led to officially introduction of this genotype as the first and a new walnut cultivar in iran in 2010 and named jamal by cultivar release committee of agricultural research, education and extension organization.