Foliar application of calcium chloride and borax affects the fruit skin strength and cracking incidence in litchi (<i>Litchi chinensis</i> Sonn.) cultivars

Abstract

The influence of foliar application of calcium chloride and borax calcium on fruit skin strength and cracking incidence in litchi (Litchi chinensis Sonn.) fruit was investigated at 25 days interval and also the evaluation of fruit skin calcium and boron contents, skin strength, ion leakage from skin discs and fruit cracking in four litchi cultivars. Significant variations were observed in different litchi cultivars and CaCl₂ and borax treatments. The means revealed that cultivar Gola had the highest fruit skin calcium content (7.67 mg/100 g DW), ion leakage from skin discs (31.11%) and fruit cracking (21.91%) but the least skin strength (2.44 kg cm^-2). Skin boron content was the highest in cultivars Gola (0.203 mg/100 g DW). Cultivar Bedana had the highest fruit skin strength (3.39 kg cm^-2) and the least mean ion leakage (18.86%) and fruit cracking (13.26%). Foliar application of CaCl₂ and borax significantly increased the mean fruit skin calcium content (4.79 mg/100 g DW), boron content (0.109 mg/100 g DW), and skin strength (2.43 kg cm^-2) from the least in the control to the highest 8.88 mg/100 g DW , 0.247 mg/100 g DW and 3.01 kg cm^-2 with CaCl₂ 3 + boron 1.5% treatment respectively, while ion leakage (35.17%) and fruit cracking (25.40%) in the control decreased to 16.17 and 11.14% respectively with CaCl₂ 3% + boron 1.5% treatment. The Ca content of the litchi fruit skin in the control vs. Rest, control vs. CaCl₂ and control vs. CaCl₂ + borax increased from 4.79 to 7.36 mg/100 g DW, 4.85 and 8.20 mg/100 g DW respectively. The boron content of the fruit skin also increased in the control vs. Rest (0.11 vs. 0.21 mg/100 g DW), control vs. CaCl₂ (0.11 vs. 0.14 mg/100 g DW), control vs. CaCl₂ + Borax (0.11 vs. 0.23 mg/100 g DW) and CaCl₂ vs. CaCl₂ + Borax (0.14 vs. 0.23 mg/100 g DW) treatments. The mean ion leakage decreased from 35.17 in the control to 24.10% in control vs. Rest, 30.26% in control vs. CaCl₂ and 22.05% in control vs. CaCl₂ + Borax. Similarly, the ion leakage decline from 30.06 to 22.05 in CaCl₂ vs. CaCl₂ + Borax means.

Key words: Boron, calcium, fruit cracking, litchi, skin strength, ion leakage.