Pollination requirements and control of fruit drop in subtropical plum (Prunus salicina Lindl.) cv. Satluj purple by foliar application of PGRs and micronutrients
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Date
2020-09
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present investigation was undertaken at Horticultural Research Centre, Patharchatta and Department of Horticulture, G.B. Pant University of Agriculture and Technology, Pantnagar, Udham Singh Nagar (Uttarakhand) in the year 2018 to 2020. The whole experiment was grouped under pollination studies, microscopic studies; and PGRs and micronutrients studies. Under the pollination studies, the various pollination methods viz., self pollination, open pollination with adjacent row of pollinizer, open pollination with distant row of pollinizer, cross pollination, supplementary pollination and floral bouque placement were compared in plum cvs. Satluj Purple and Kala Amritsari. The results demonstrated that cross pollination was most effective in terms of initial fruit set (37.11%), final fruit retention (15.80%), yield (26.21 kg/tree), fruit length (2.90 cm) and fruit width (3.11 cm) in Satluj Purple, while the same treatment recorded the minimum fruit drop (84.19%). In cv. Kala Amritsari, self pollination resulted in the highest initial fruit set (56.08%) and yield (37.12 kg/tree), whereas the maximum fruit length (2.60 cm) and fruit width (2.71 cm) was obtained under cross pollination Among the two cultivars under study i.e., Satluj Purple and Kala Amritsari, the pollen viability (90.45%) and germination (39.54%) was estimated highest under Satluj Purple, whereas the maximum polar length (29.13μm) and equatorial diameter (19.76μm) of pollen grains was measured in Kala Amritsari. The microscopic studies demonstrated the presence of gametophytic self incompatibility in Satluj Purple, where the growth of self pollen was arrested in the lower half of the style; however, cross pollen successfully entered the ovary region. Studies on the effect of PGRs and micronutrient reveals the foliar application of plant growth regulators (NAA @ 10 ppm, NAA @ 15 ppm, NAA @ 20 ppm, NAA @ 15 ppm + urea @ 2%, 2,4-D @
5 ppm, 2,4-D @ 10 ppm, 2,4-D @ 15 ppm and 2,4-D @ 10 ppm + urea @ 2%) and micronutrients (Borax @ 0.5%, ZnSO4 @ 0.4%, ZnSO4 @ 0.5%, ZnSO4 @ 0.6% and ZnSO4 @ 0.5% + urea 2%) significantly improved the fruit retention, yield and quality attributes of plum cv. Satluj Purple. The pooled analysis showed the maximum fruit retention (37.43%), fruit yield (28.29 kg/tree), fruit length (3.68 cm), fruit width (3.46 cm), fruit weight (33.50 g), fruit volume (32.76 ml), fruit firmness (4.19 lbs), pulp weight (32.29 g), pulp-stone ratio (25.77), TSS (14.41 oBrix), TSS/acid ratio (17.47), total sugar (10.41%),
reducing sugar (7.26%) and ascorbic acid (12.63 mg/100 g), estimated under the application of NAA @ 15 ppm + urea @ 2%, while the same treatment recorded the minimum fruit drop (62.57%) and titratable acidity (0.83%) followed by 2,4-D @ 10 ppm + urea @ 2% in the same sequence. The minimum fruit retention, yield and physico-chemical attributes were observed under the control. Thus, it can be concluded that plum cv. Satluj Purple possess gametophytic self incompatibility, where the growth of self pollen is arrested in the lower half of the style, whereas cross pollen (Kala Amritsari) successfully entered the ovary region. Therefore, the planting of cv. Kala Amritsari as a pollinizer along with the application of NAA @ 15 ppm + urea @ 2% is recommended for the control of fruit crop and improvement in other quality attributes of plum cv. Satluj Purple.