Influence of Rootstocks and Harvest Date on the Fruit Quality of the ‘Nadorcott’ Mandarin During Cold Storage

Cold storage is one of the main ways to coordinate harvesting and packinghouse operations for extending the marketing period. In Morocco, for the new citrus varieties, limited research has been undertaken on the evolution of the fruit quality during cold storage. In this paper, we present results of a cold storage trial of ‘Nadorcott’ mandarin fruits. Fruits were harvested from a rootstock trial carried out in SEBNAK orchard and stored in Mazaria packinghouse facilities in North-West of the Morocco. The objective of the study is to assess the effects of the harvest dates, the storage duration and three citrus rootstocks: ‘Carrizo’ citrange (CC), C-35 citrange (C35) and Citrus macrophylla L (M) on the internal quality and weight loss of the ‘Nadorcott’ mandarin fruits stored at 6 °C and 80% ±5 % humidity. Fruits were harvested at three dates and the quality parameters (juice content, titratable acidity, total soluble solids and weight loss) were evaluated after 0, 20, 40 and 60 cold-storage days. Fruit quality characteristics varied according to the rootstock type, storage duration and harvesting dates. At harvest, juice content was affected by different rootstocks: C-35 and CC showed the highest values, with about 50 % compared to that of M with only 44%. In addition, fruits harvested in March (D3) were less juicy than those harvested in January (D1) and early February (D2). The juice content falls more or less rapidly during the cold storage depending on the rootstocks and harvest dates. For the three harvest dates (D1, D2 and D3) and 60 days storage, the ‘Nadorcott’ mandarin fruits on M recorded the lowest juice percentage with values of 31, 38 and 30% respectively. At late period (D3), the acidity in fruit juice dropped to the lowest levels reaching a rate of 0.68 % for CC and M and 0.77 % for C-35. With regards to TSS, CC and C-35 had higher TSS (total soluble solids) percentage compared with fruits from trees on M. Date of harvest and cold-storage period have no significant effect on this parameter. Similarly, the weight loss of ‘Nadorcott’ fruit was not affected by the rootstock.