Determination of the Appropriate Harvest Time and Storability of some Cultivars and Promising Genotypes of Quince (Cydonia oblonga Mill.) in Cold Storage Conditions

The evaluation of storage characteristics and determination of resistance to post-harvest disorders in horticultural crops is highly important. ‘Viduja’ as new quince cultivar and KVD2 and KVD4 promising quince genotypes were collected from different regions of Isfahan Province. As these cultivar and promising genotypes are new, it is necessary to determine the most appropriate harvest time for them based on effective harvest indices. This research was carried out for the determination of the best harvest time and storage period of these promising quince cultivar and genotypes.

This experiment was carried out on 'Viduja' as new cultivar and KVD2 and KVD4 genotypes as promising genotypes and 'Isfahan' cultivar as control, which was grafted on hawthorn seedling rootstock. In April, the full bloom time of these cultivars and genotypes was monitored to report harvest time based on the number of days after flowering for each cultivar and genotype. Fruits were harvested on October 6th, 14th, and 21th, 2016 in the horticultural research station of Mobarakeh. Fruits were transferred to cold storage with 0±1°C and 90±5% R.H. for five months. Some traits were measured in the harvesting date and also at the end of every month. These traits included weight loss percentage, fruit firmness, TSS, TSS/TA, pectin, total phenol, surface browning and decay percentage. The experiment was carried out as a factorial experiment in a completely randomized design with three replicates (10 fruits in each replicate).

'Viduja' cultivar and KVD2 and KVD4 genotypes were early flowering and had similar flowering time. Isfahan quince cultivar was late flowering and had moderate overlap with KVD2 and KVD4 genotypes. According to the results, the highest weight loss was observed in the fifth month of storage. In this month, 'Isfahan' and 'Viduja' cultivars showed the most and the least weight loss, respectively. Others showed increased water loss and reduced fruit weight with increased storage time. For example, with increasing the duration of storage in the cold storage, the weight loss of 'Gorton' quince cultivar increased. In all cultivars and genotypes, the highest TSS and TSS/TA were founded in the third harvest and fifth and fourth month of storage. Mosharraf and Ghasemi (34) reported that TSS in the last harvesting time and after five months of storage time was 20.16% in 'Isfahan' cultivar. In their research, TSS was 14.75% in harvesting time that was less than the rate of this trait in the current study. The highest TSS/TA belonged to 'Isfahan' and 'Viduja' cultivars. The highest fruit firmness was obtained at harvest time of 'Isfahan' and KVD2 genotype, and the lowest of that was observed in five months after the storage of KVD4 genotype. In the Esme quince cultivar, the fruit firmness in the third harvest quickly decreased, and after six months it was 3 kg cm-2. At harvesting time of KVD4 genotype, the highest phenol content was observed. 'Isfahan', 'Viduja' cultivars and KVD2 genotype showed the lowest phenol content after five months of storage. Increasing the storage period resulted in a decrease in phenol content in all cultivars and genotypes. Similarly, other researchers showed that the total phenol content gradually decreased with prolonged fruit storage (6 and 7). KVD4 genotype and 'Isfahan' cultivar showed the most pectin content at harvesting time. Increasing the storage time reduced the rates of pectin. According to Mosharraf and Ghasemi (39), increased storage period reduces pectin content in Isfahan cultivar fruits. The fruit surface browning was begun from the fourth month of storage, and there was no significant difference with the amount of this trait in the fifth month. Surface browning in the third harvest of Esme cultivar was also more than the previous harvestings, and eventually reached 70% (30). With prolonging storage time, the decay percentage increased. The first decay was observed from the third month of storage and reached its highest level in the fifth month. Isfahan cultivar had the highest percentage of decay. Other cultivar and genotypes had no significant difference in decay percentage.

Conclusions:

 Finally, the best harvesting time for 'Isfahan', 'Viduja', KVD2 and KVD4 cultivars and genotypes were 185, 200, 200 and 193 days after full bloom respectively. Fruit storage in the cold for four months is advisable for 'Isfahan' and 'Viduja' cultivars and KVD4 genotype. In KVD2 genotype fruits, five-month storage is recommended.