Effect of meteorological factors on fruit maturation and the prediction of optimum harvest for apples.

Apple maturation was found to be largely governed by meteorological conditions, viz. the temperature
and precipitation during the pre-bloom period and the first half of the post-bloom period.
The meteorological and physiological factors affecting three strains of 'Red Delicious' and 'Golden
Delicious' apples cultivated in an orchard in the Simla Hills were studied during four consecutive
seasons and significant correlations were established. The optimum harvest period was precisely
predicted by the meteorological conditions well in advance, and the latter showed significant correlations
with the actual optimum harvest period determined by starch pattern index and seed
colour index. Based on these meteorological factors, a "key year" concept was evolved to reliably
predict the optimum harvest period. Since this concept was based on all the interrelated meteorological
conditions, a prediction would be more reliable under varying climatic conditions in any
ensuing season if considered for the period of 242 days from November to June.