Effect of pruning severity and spraying some chemical substances on growth and fruiting of guava trees

American-Eurasian J. Agric. & Environ. Sci., 5 (6): 825-831, 2009 ISSN 1818-6769 © IDOSI Publications, 2009

Effect of Pruning Severity and Spraying Some Chemical Substances on Growth and Fruiting of Guava Trees
A.E.A. Shaban and G.M.M. Haseeb Pomology Department, Faculty of Agriculture, Cairo University, Giza, Egypt
Abstract: An experiment was carried out on 25 years old guava trees hybrid I grown at the nursery of the faculty of Agriculture, Cairo University, Giza, Egypt during the two successive seasons, 2005 and 2006. Trees were subjected to the following pruning treatments, pinching, moderate or severe pruning and sprayed on 15th February after pruning with potassium nitrate (1, 2 and 4%) or ethephon (200, 400 and 600 ppm) or dormex (0.5, 1 and 1.5%) compared with the control(sprayed with water only), to study their effect on inducing growth and yield of guava trees. Results showed a significant increase in average index number of bud burst and shoot length with severe pruning plus spraying potassium nitrate at 4% concentration compared to the other treatments. Moderate pruning plus spraying ethephon at 600 ppm produced the highest number of new shoots in both seasons. Dormex at 1.5% with moderate pruning gave the highest average index number of flower bud burst in the first season. Meanwhile, ethephon at 600 ppm with severe pruning produced the highest average index number of flower bud burst in the second season. A pronounced and significant increase in initial fruit set was found with moderate pruning and application of potassium nitrate at 4%. Also, pruning treatments with spraying chemicals substances improved tree yield. Key words: Guava % Pruning % Potassium nitrate % Ethephon % Dormex % Growth % Fruit set % Yield INTRODUCTION Guava (Psidium gujava L.) belongs to family Myrtaceae, the apple of tropics and it is one of the highest fruit in area and production after citrus, mango, grapes and banana. The fruit is extensively used in the processing