EFFECT OF PHYSIOLOGICAL AGE AND GROWTH REGULATORS ON CALLUS BROWNING OF COCONUT ENDOSPERM CULTURE IN VITRO

The possibility of physiological age and growth regulators affecting callus browning ofcoconut endosperm was investigated. Solid endosperm explants of four coconut fruits fromsame brunches of two coconut cultivars “Samoan Dwarf ” were grown on modified Murashigeand Skoog (MS) formula with addition of 10 mg l putresine, 2.50 g l activated charcoal (AC),1.70 g l phytagel, 0, 10 , 10 , 10 , 10 M 2,4-dichlorophenoxyacetic acid (2,4-D) or 4-amino-3,5,6-trichloropicolinic acid (Picloram) combined with 10 M 6-benzylaminopurine (BA).Callogenesis occurred on 98.83% of explants. Callus browning between different physiologicalages (antipodal and micropylar tissues) of coconut endosperm at 9, 26 and 31 weeks of culture(WOC) was significantly different, but not at 16 and 21 WOC. Auxins of 2,4-D and Picloramdid not affect significantly callus browning of endosperm cultures. Auxin doses at 10 , 10 , and10 M decreased significantly callus browning at 9 and 16 WOC, respectively, but at 10 Mbrowning was less significant compared to other doses at 21 WOC. Auxin dose at 10 M causedless significant browning compared to other doses at 31 WOC. The addition of BA decreasedsignificantly callus browning at 9 WOC, but did not affect callus browning thereafter.