OXIDATIVE BROWNING CONTROL AND CALLUS INDUCTION IN LOQUAT PETIOLE AND VEIN IN VITRO CULTURE

Abstract

A series of experiments were carried out to investigate the effects of leaf developmental stage, positions of petioles and veins, cold treatment at 4°C, strength of MS medium and growth regulators on oxidative browning, and callus induction in loquat. Petioles and veins, harvested from young leaves of ten-year-old trees, were used as experimental materials. Leaf explants collected five day after bud sprouting were prone to severe browning, whereas leaf explants collected ten days after bud sprouting showed minor browning symptoms and rapidly produced large quantity of granular light-green tight calluses. Leaf explants collected 15 days after bud sprouting also showed minor browning symptoms and rapidly produced large quantity of granular calluses, but the calluses were yellow and loose. Petioles were found to be the most suitable explants in terms of callus quantity and quality. Cold treatment at 4°C had no evident effects on browning control and callus formation. Granular, light green and tight calluses were formed in 1/8 MS medium supplemented with 1.0 mg/L BA, 1.5 mg/L 2,4-D, 0.4 mg/L NAA, and 1.5 g/L PVP.