Effect of environment on fruit growth and quality in early heating cropping type of satsuma mandarin (Citrus unshiu Mark.)
2014
Yano, T. (Oita Prefectural Agriculture, Forestry and Fisheries Research Center (Japan). Agricultural Research Division, Fruit Tree Group) | Soda, Y. | Nagao, S. | Yamasaki, R. | Mizuuchi, I.
In order to establish an energy-saving temperature regime, farmers' greenhouses (32 greenhouses) were researched on the environment, fruit growth and quality in early heating cropping type of Satsuma mandarins (Citrus unshiu Mark.). The following knowledge was obtained. 1 The standardized fruit growth rate (GRFsub(St)) correlated linearly (P<0.01) with the night temperature (12-24degC) at 30-59 days after full bloom (DAFB). 2 The GRFsub(St) correlated quadratically (P<0.05) with the vapor pressure deficit (VPD) at 30-59 DAFB, thus the existence of the VPD which maximize the fruit growth was shown. 3 On the relation of the soluble sugar content (SSC) and the air temperature, a negative correlation (P<0.01) was recognized between the SSC at 120 DAFB and the day temperature (22-26degC) at 60-89 DAFB. Similarly, a negative correlation (P<0.05) was recognized between the SSC at 150 DAFB and the night temperature (19-25degC) at 60-89 DAFB. 4 On the relation of the titratable acidity (TA) and the air temperature, the TA at 120 DAFB was correlated negatively with the day temperature (20-26degC) and the night temperature (17-25degC) at 90-119 DAFB. In addition, the TA at 120 DAFB was also correlated with the daily mean temperature (19-25degC) at 90-119 DAFB. 5 Considering the balance of the SSC and the TA, it might be rational to control the daily mean temperature as height as 22-23degC at 60-119 DAFB. 6 An adequate air temperature range for the fruit growth in early heating cropping type of Satsuma mandarin was reconfirmed as 20-25degC. An energy-saving temperature regime, day/night temperatures were proposed as follows: 25/23degC at 30-59 DAFB, 25/23degC at 60-89 DAFB, and 25/22degC at 90-119 DAFB.
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