Leaf Retention Influences Photosynthetic Activities, LAI and PAR in Clone-2A Grapevine

Abstract

The study was conducted during October, 2023 to March, 2024 at ICAR-National Research Centre for Grapes, Pune, Maharashtra, India to assess the leaf area requirement of Clone-2A grape variety. The experiment was laid out using Randomized Block Design (RBD) with variation in leaf on a fruit-bearing shoot such as 10,12,14,16 and >16 leaves above the bunch as five treatment replicated five times. The parameters measured were leaf area, leaf area index (LAI), photosynthetically active radiation (PAR), photosynthetic rate, stomatal conductance, chlorophyll content, average bunch weight, berry weight, yield vine^-1, total soluble solids (TSS) and acidity. Maximum bunch weight (450.60 g), 50-berry weight (182.60 g), TSS (18.25°B) and yield vine^-1 (19.46 kg) were recorded in 14 leaves shoot^-1 above the bunch treatment.  The highest photosynthetic activity such as assimilation rate (11.25 µmol CO₂ m^-2 s^-1) and transpiration rate (2.85 mmol H₂O m^-2 s^-1) and total chlorophyll content (35.28 mg ml^-1) was observed in the same treatment.  Minimum bunch weight (380.10 g), 50-berry weight (155.22 g), TSS (16.60°B) and yield vine^-1 (16.38 kg) were observed in >16 leaves above the bunch treatment. However, retaining 14 leaves above the bunch in a shoot with 2861.42 cm² leaf area shoot^-1, 85842.60 cm² leaf area vine^-1 and 1988.00 cm² leaf area bunch^-1 were found sufficient for quality grape production in Clone-2A grape variety spaced at 9×5 ft² distance.