‘ Kinnow’ mandarin (Citrus nobilis L.× Citrus deliciosa T.) is an important marketable fruit of the world. It is mainstay of citrus industry in Pakistan, having great export potential. But out of total production of the country only 10% of the produce meets the international quality standard for export. Pre-harvest fruit drop and poor fruit quality could be associated with various issues including the plant nutrition. Most of the farmers do not pay attention to the supply of micro nutrients which are already deficient in the soil. Furthermore, their mobility within plants is also a question. Zinc (Zn) is amongst those micronutrients which affect the quality and postharvest life of the fruit and its deficiency in Pakistani soils is already reported by many researchers. Therefore, this study was carried out to evaluate the influence of pre-harvest applications of zinc sulfate (ZnSO4; 0, 0.4%, 0.6% or 0.8%) on pre-harvest fruit drop, yield and fruit quality of ‘Kinnow’ mandarin at harvest. The treatments were applied during the month of October i.e. 4 months prior to harvest. The applied Zn sprays had significant effect on yield and quality of the “Kinnow” fruit. Amongst different foliar applications of ZnSO4applied four months before harvest, 0.6% ZnSO4 significantly reduced pre-harvest fruit drop (10.08%) as compared to untreated control trees (46.45%). Similarly, the maximum number of fruits harvested per tree (627), fruit weight (192.9 g), juice percentage (42.2%), total soluble solids (9.5 °Brix), ascorbic acid content (35.5 mg 100 g-1) and sugar contents (17.4) were also found significantly higher with 0.6% ZnSO4 treatment as compared to rest of treatments and control. Foliar application of 0.6% ZnSO4 also significantly improved total antioxidants (TAO) and total phenolic contents (TPC) in fruit. In conclusion, foliar spray of ZnSO4 (0.6%) four months prior to harvest reduced pre-harvest fruit drop, increase yield with improved quality of ‘Kinnow’ mandarin fruit.

Going towards sustainable fruit culture, it is very important that soil fertility should maintain by adopting the proper weeds control and adding the organic matter. This research was carried out to identify the most suitable weed control method for Kinnow orchard. The plants of Kinnow at the age of 6 years grown under drip irrigation were selected. Weeds of orchard were managed by mulching (wood chip and black polyethylene), mechanical (cultivator and rotavator) and chemical (glyphosate) methods. Mechanical weed control was taken as control treatment. The plants where wood chip mulching was used for weed control showed maximum increase in shoot length (24.00 cm), chlorophyll contents (84.00 SPAD value) and yield (11.88 ton ha-1) followed by the plants where weeds were controlled with chemical control while lowest shoot length (12.00 and 12.33 cm), chlorophyll contents (41.00 and 42.67 SPAD value) and yield (3.80 and 4.70 ton) was achieved in cultivator and rotavator treatment respectively. Wood chip mulch also improved soil physical properties by reducing bulk density (1.49 Mg m-3), soil penetration resistance (785.33 kPa) and by enhancing soil organic matter (1.17%), hydraulic conductivity (34.50 mm/hr^-1) and soil microbial biomass carbon (159.68 g kg-1) followed by glyphosate control while lowest values of soil physical properties were obtained in cultivator and rotavator weed control. Wood chip mulch also reduced weed dry weight (45.25 g) and efficiently controlled weeds (95.66%) as compared to other weed control methods. In this case, wood chip mulch performed better in all studied parameters than plastic mulch, rotavator, cultivator and glyphosate weed control. So, wood chip mulch should be recommended to citrus grower for improving soil physical properties and yield.