Effect of Soil Moisture Content, Micro Weather Condition Variations on Fruit Cracking and Trees Stress as Water State Fluctuation Characters of Fruit Tissues in Late Maturing Citrus ‘Kanpei’ during Fruit Growth

This experiments were conducted for the purpose of analyzing factors turgor pressure difference between fruit pericarp and vesicle tissue, as the fruit shape index in the Synhyo, sever fruit cracking rate and Sangye, mild fruit cracking rate rain shelter green house during the fruit growing season. We are also investigated soil moisture content, variations and micro-climatic conditions change in the houses that promote this turgor pressure difference. The difference in the turgor pressure between the pericarp and the vesicle tissue of the Shinhyo, 0.42-1.31 was higher than the Sangye, 0.14-0.47. The soil moisture content varied from 22.59% to 27.55 in the Synhyo and 26.28% to 35.5%, which was larger fluctuations than that of the Sangye, but the content higher about 3.69%-7.95%. The average temperature change in the house was 17.82oC-29.14 °C in the Shinhyo, but 15.24-28.25 °C for Sangye, 0.89-2.58 °C lower than Shinhyo. In addition, the average relative humidity was 67.76% - 83.28% in the Shinhyo and 71.31%-85.83% for Sangye, which was 2.55-3.55% lower than that of Sangye. The average solar radiation was 230.65μmol-310.26μmol in the Sangye, about 22.13μmol higher than Shinhyo 208.52μmol-311.92μmol. In conclusion, we are thought that the Shinhyo green house’s soil moisture content, variation and micro-climatic condition factors promote transpiration of canopy due to higher temperature in the summer and early autumn season. The leaf water potential fell to -4.49Mpa with the above factors in August, maximum quantum efficiency (Fv/m) in vegetative branch lower, and higher endogenous plant hormone jasmonic acid (JA) concentration of the fruit shape index rate as leaf and flesh than Sangye in September, and excessive water stress in the trees could be seen as a major factor that promotes the turgor pressure difference between pericarp and the vesicle tissue resulting in severe fruit splitting.