Investigation and estimation of chill and heat requirements of flower buds of some promising almond genotypes and cultivars

The aim of this study was to investigate the chill and heat requirements of flower buds of 8 foreign and domestic commercial cultivars and promising domestic almond genotypes during 2019 and 2020 as a factorial experiment based on a completely randomized design with 3 replications and two factors including five cultivar type (Tuono, Nanpariel, Mamaie, Shahroud 12, Rabi) and three genotypes (1-16, 13-40, and D11) and the number of child and heat requirements hours 0-7.2 ° C (zero, 50, 100, 200, 300, 400 , 500, 600, 700 and 800 hours) were performed at the One hundred hectare research station of Horticultural Research Institute. Based on the results, the studied genotypes and cultivars showed a wide range of chill and heat requirements. The number of days to break dormancy at 0 to 7.2 ° C varied between 17 days in the Mamaie cultivar and up to 58 days in the D11 genotype. Mamaie cultivar was recognized as the earliest cultivar among the cultivars and genotypes studied which after 17 days from the beginning of the accumulation of chill requirements and with 50 hours of chill between 0-7.2 ° C reached 50% of flowering. Mamaie cultivar with 7128 Growth Degree Hour (GDH) and genotype D11 with 11088 Growth Degree Hour had the highest heat requirement. The results showed that with increasing the number of hours of chilling requirement, the number of days required for buds to bloom significantly decreased. In general, Mamaie and Rabi cultivars were identified as early flowering cultivars with the lowest chill requirement and D11 genotype as the late flowering cultivars with high cold requirement.