摘要：India with its unique agro climate conditions favours cultivation of number of fruits. For decades together typical temperate fruits like apple, pear, stone and nut fruits were grown with adequate production and productivity. However, during the past 10-15 years on account of global warming many of the sites which were potential hub for temperate fruit cultivation have been rendering unfit for their cultivation. The productivity of temperate fruits especially apple in Himachal Pradesh is declining at a faster rate. Average yield of apple in India has been estimated at about 7.0 t/ha which is far below the level of 30 t/ha in most of advanced countries. The productivity has also not kept pace with the expansion in area under temperate fruits due to various biotic and abiotic problems faced by the farmers in the Himalayas. This has caused a serious concern not only to the hill farmer community but also to researchers, development agencies and policy planners. With the global warming, the decline in productivity is being mainly attributed to changing climatic scenario. It is clearly reflected that standard apple cultivar 'Starking Delicious' and 'Red Delicious' would not flower and fruit when chilling units are not adequately fulfil. Hence there is an urgent need to select appropriate low chill cultivars for plantation at low elevation location so that consistent yields are obtained and crop failures avoided. Results obtained revealed that cultivar 'Tropical Beauty' was the best genotype for the characters like plant height (6.60m), plant spread (5.67m), trunk girth (64.50cm), tree volume (111.20m3), leaf area (60.67cm2), number of fruit set per unit shoot length (15.25%), yield per plant (15.82Kg), fruit weight (129.80g), total sugar (8.48%) and non-reducing sugar (1.92%). Cultivar 'Parlin's Beauty' was the best genotype for characters like fruit breadth, reducing sugar and was recorded as promising next to 'Tropical Beauty' for many desirable traits. Cultivar 'Chahla' was superior for high number of flowers per unit shoot length, shoot length, fruit length and long duration of flowering. Earliest flowering was observed in cultivars 'Anna'. Maximum phenotypic coefficient of variability was observed for fruit yield per plant. High heritability and high genetic advance indicated presence of additive gene action for these traits. To meet the bulk requirements of the processing units and horticultural diversification, apple cultivation can be extended to mid hills by planting suitable low chilling cultivars. The low productivity of apple has become a serious concern for the farmers, research workers and development agencies at national and state level for the last two decades. Several factors can be attributed to the declining trend in productivity like expansion of apple cultivation to marginal areas, monoculture of Delicious varieties, declining standards of orchard management, improper chilling requirements and the fluctuating abnormal climatic conditions.
