Correlation between Content and Ratio of Fruit's Mineral Elements at Harvest and Postharvest Life of Kiwifruit Cv. Hayward in Orchards of Eastern Part of Guilan Province

The main factor affecting fruit quality and post-harvest loss in kiwifruits is improper tree nutrition. In this study, fruits were harvested from 24 different orchards in the east of Guilan province when the total soluble solid content of the fruit was 6.2°. percent the fruts was. Fruits’ mineral content such as nitrogen, phosphorus, potassium, calcium and magnesium, the mineral elements ratios and also fruits firmness were measured after harvest. Thereafter, fruits were transferred to cold storage at 0 ºC temperature and 90% relative humidity and after 15 weeks, fruit tissue firmness, water loss, ethylene content and respiration severity were measured. There was a significant positive correlation between fruits tissue firmness with fruit calcium content, but a significant negative correlation with potassium and nitrogen content, N:Ca, N+K:Ca. K:Ca and K+Mg:Ca ratios. At the end of storage, there was a significant positive correlation between fruit tissue firmness with calcium content at harvest time and a significant negative correlation with nitrogen, phosphor us and potassium content and N:Ca, N+K:Ca, K:Ca and K+Mg:Ca ratios. Furthermore, fruits’ weight loss showed a significant positive correlation with potassium content. There was a significant negative correlation between ethylene level and fruit tissue firmness at the end of storage and a positive correlation with N:Ca and N+K:Ca ratios. Cluster analysis divided kiwifruit orchards into two main groups. In conclusion, the results showed that the kiwifruit mineral elements’ content and ratio at harvest time can be used as an effective factor for evaluating post-harvest life of kiwifruits.