Influencing of Some Factors on Regreening of “Valencia” Orange Fruits

Abstract

Many factors involved the regreening process of “Valencia” oranges under warm climate. Researchers focused on the difference between day and night temperatures in relation to the regreening process. This study paid a special attention to the branch-bearing fruits whether its temperature or its nitrogen content before the regreening process till appearance of regreening. In addition, growth degree hours (GDH), which took into consideration the duration of effective temperature from sunrise to sunset considering the minimum degree as 13°C was also studied. Thus, the main objective of this study was to evaluate the role of the branch-bearing fruit temperature and nitrogen content on the regreening process during 2012 and 2013 seasons. The results proved that regreened “Valencia” fruits were growing on branches with greater nitrogen content, higher temperature and GDH. Furthermore, there were a high correlation between cumulative nitrogen content, temperature of branch-bearing fruits and GDH and the incidence of regreened “Valencia” oranges. Moreover, warm temperature throughout the season especially the period preceding harvest enhanced the uptake of nitrogen which reflected on more regreened “Valencia” oranges.