2017 ASHS Annual Conference

Hydrolytic enzymes have been shown to relate to organ abscission in plants. However, it is not clear about the nature of hydrolytic enzymes and their dynamics of change in balsam fir postharvest needle abscission. It is also not known whether the changes in the levels would explain the needle retention resistance in clones. An experiment was conducted to evaluate the dynamics of change in hydrolytic enzymes (cellulase and pectinase) during postharvest and uncover their relationship to the needle abscission resistance (NAR). A total of 264 branches were collected from low and high genotypes with 4 replicates. The treatments included: genotypes and days. Water was supplied to branches during a 72-day period. Water usage and needle loss were recorded every 2 days. Water usage decreased (P<0.05) with increasing days. The cumulative needle loss percentage was significantly affected by the interaction between clone and day (P<0.05). In this experiment, the low NAR clone began to lose needle sooner and reached 50% of needle loss faster than that of the high NAR clone. Cellulase (EC 3.2.1.4) and pectinase (EC 3.2.1.15) activities in the needle were evaluated every 3 days. Cellulase activity of low NAR clone was significantly higher (P<0.05) than that of high NAR clone through the whole experiment period. The pectinase activity was not affected by neither genotypes nor the days of postharvest. These results indicate that higher cellulase activity could be the reason for higher needle abscission in balsam fir, postharvest. Cellulase activity was also found to be significantly high in low NAR clone, which could be a possible reason why the low NAR clones loose needles early.