Effect of Plant Architecture on the Performance of Two High-chill Pear Cultivars

Abstract

Pear growing in subtropics began with the advent of low-chill pears, but their fruit quality is inferior to high-chill European/Oriental pears. Thus, the best way to produce high-chill pears in subtropics is by topworking them on the low-chill pears. To attain this, pruned wood with spurs of `Doyenne du Comice' (DCP) and `Victoria pear' (VP) cultivars were collected in January from Hort Expt Center Chaubatia, India (6825'ASL), and tongue grafted on low-chill `Pant Pear-18' (PP18). The grafting was at different heights on trees using 25-cm and 1-m long stocks on Tatura trellis-trained PP18 trees at the Hort. Research Center, Pantnagar (760' ASL). More than 90% grafts succeeded and both DCP and VP produced high quality fruits, but DCP grafts had an edge over VP scions. Both high-chill cultivars topworked on 25-cm stocks had better grafting success (95%) than the scions topworked on 1-m stocks (92%). The increase in topworking heights on stock trees reduced the floral spur numbers in both scions grafted on 25-cm stocks, but not on the scions grafted on 1-m stocks. With the incremental height of topworking irrespective of the length of stocks, the percentage of fruit set was curtailed by 28% and 12% for the DCP and VP scions, respectively. Irrespective of the topworking heights and stock lengths, the fruit yield for DCP (12.5 lbs/tree) was markedly higher than for VP (7.9 lbs/tree). Fruit quality attributes judged by organoleptic testing, TSS, total sugars, acidity, and ascorbic acid, were better for both DCP and VP than for PP18 and other local pear cultivars. The reuse of previous year's scions topworked even after artificial chilling and/or GA3 application to supplement chilling exhibited no fruiting advantage over the grafting using fresh scions.