Effects of harvest time on fruit quality and storability of ‘Red Sun’ kiwifruit

The Red Sun kiwifruit is the most popular variety of kiwifruits，while this variety is also commonly found in markets，the fresh preservation technology limits its application in kiwifruit industrial development. Appropriate harvest time，proper storage，and transport can contribute to good quality of kiwifruit. The Red Sun kiwifruit varieties from Pujiang county，Sichuan province was used as experimental materials to study the effects of harvest times（ 131，136，141，146，151，and 156 days after full bloom） on the physiological traits during the ripening and softening periods（ RSP，that is，the date between the day of harvest and that of the flesh firmness lower than 0.5 kg/cm2） of kiwifruits at the storage temperature of 25（±1）℃. Soluble solids content（ SSC） ，titratable acids（ TA） ，reducing sugars（ RS） ，vitamin C（ Vc） ，flesh firmness and dry matter content in fresh fruits and postharvest softening fruits were analyzed，respectively. The results showed that there was a negative correlation between TA and RSP，RS was negatively correlated with RSP，Vc was positively correlated with RSP，and the change of RS and RSP was more consistent. These results suggested that RS might be a key factor influencing RSP of Red Sun kiwifruit.Comparison with the fresh fruit at the harvest time，the SS content of ripening and softening fruit during the storage increased by about 10%，and TA decreased by about 0.1%. RS，Vc，and dry matter content were mainly affected by the harvest times and were less affected by fresh fruits. Therefore，the storability of kiwifruit could be predicted based on RS at harvest time of Red Sun kiwifruit. Quality of kiwifruit cannot be improved during the storage；thus，it is important to harvest fruits at the proper stage and size with different harvesting schemes. kiwifruit industry is in urgent need of different harvesting schemes for preservation，shelf life extension and better maintain the quality of fruit.