온주밀감의 과실 품질에 미치는 타이벡 멀칭의 효과

Abstract

This study investigated the effect of drought stress on the fruit quality, such as the sugar content and acidity, in the Satsuma mandarin with Tyvex mulching with dryness processing(Mulching 1), compared to Tyvex mulching with trickle irrigation once a week from 20th October after dryness processing(Mulching 2) and no mulching treatment(Control). The results are as follow; In the sugar content of the fruit juices, the content in mulching 1 was 12˚Brix, which was the highest, the content in mulching 2 after starting trickle irrigation marked a down tendency a little, but it was 10.5˚Brix, which was 0.5˚ higher than the control. In the acidity of the fruit juice, the acidity in mulching 1 was 1.4%, which was the higher than the rest, the acidity in mulching 2 was 1.0%, lower than the control. The respiration speed in mulching 1 with dryness processing was slightly quick compared with control, and that of mulching 2 with trickle irrigation marked the highest level on November 30th. The leaf water potentials in mulching 1, 2 during dryness processing were lower than the control, but mulching 2 with trickle irrigation after dryness processing marked 0.7MPa higher than mulching 2 preserved dryness processing. The juice sac water potentials both in mulching 1, 2 were remarkably lower than the control at growing and ripening seasons, but increased rapidly to 0.2MPa at harvest season, to a slightly low degree of the potentials in the control. The osmotic potentials of the juice sac organization of the fruits in mulching 1, 2 were -1.4MPa at growing and ripening seasons, which was lower compared with the control, but at harvest season the potentials in both mulching 2 with trickle irrigation and mulching 1 with dryness processing were -1.2MPa, -1.4MPa respectively, they were higher than that of the control. The tugor pressure of the fruit in mulching 1, 2 were 0.4MPa, slightly higher than the control, at harvest season the tugor pressure in mulching 1 was higher than that in the control, but the tugor pressure in mulching 2 was lower than that in the control. The water content ratios in mulching 1, 2 had no difference in the control at growing season, at ripening season the ratios in mulching 2 was higher than those in mulching 2 and the control, on the contrary the dry rate was lowest. The same order was kept at harvest season. From the study, the fact that the sugar content of the fruit under drought stress increases was verified, it is believed that the increases in the sugar content was caused not by the process of condensation, but by the positive control of the osmotic potentials to deal with the tugor pressure of the fruit affected by drought stress. Also, after trickle irrigation the decreases in the sugar content and acidity was observed, the reason was that the organic acid is used by the material of the respiration process, it was verified by that there was the strong negative correlation between the respiration speed and the organic acid content.