Studies of some pre harvest treatments on growth and fruit quality of guava fruits

Abstract

This investigation was done during two successive seasons (2009/2010 and 2010/2011) on 10 years old (Psidium guajva, L) seedy guava trees at Mariout Research Station of the Desert Research Center. This investigation aimed to compare fruit growth curve of summer and winter guava fruit also study the effect of some treatments: 1- control (sprayed with water only). 2- Calcium chloride at 1%. 3- Calcium nitrate at 0.6%. 4- Paclobutrazol at 150 ppm. These treatments were sprayed twice (the first spray was applied 80-85 days after full bloom at August in spring summer (SS) guava and first week of December in Autumn winter (AW) guava, the second spray was done ten days after the first spray in both) to study the impact fruit quality in guava. Guava from the (SS) season grew faster (total= 122 days) than the (AW) fruit that required 186 days. Weight, volume and diameter constituents were higher of fruit in (SS) fruit than in the (AW) fruit, while total soluble solids and acidity were higher in (AW) than in the (SS) fruit. The obtained results showed that, spraying with calcium nitrate at 0.6% with spring summer date gave the lowest values of titratable acidity and the highest values of total sugars. Moreover, spraying with calcium nitrate at 0.6% with autumn winter date gave the lowest values of weight loss, the highest values of fruit firmness of flesh, the lowest values of decay percentage, the highest values of total soluble solids and the lowest values of incidence of rot% in both seasons at shelf life storage about 10 days. We can be recommended by spraying calcium nitrate at 0.6% 80-85 days after full bloom in both dates to get the best results of fruit quality.