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 Igrown 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 thecontrol(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, pruningtreatments 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 processingindustry and many delicious products such as Jam, Jelly, excellent salad and pudding. Pruning is one of the oldest cultural practices which is practiced in temperate and sub-tropical fruit crops to bring a balance between vegetative and reproductive growth of the plant. In guava the flowers and fruits are borne on current season growth. A light annual pruning is considered necessary to encourage newshoots after the harvest. A better understanding of the effect of pruning is the need of an hour. The pruning of guava has not received much attention, when we see its economic importance, it can be justified. Lal  indicated that the yield of guava cv Sardar was improved by pruning. Also, Salah  produced the highest bud emergence of guava by using severe and moderate pruning. The time andintensity of pruning affected guava cv. Paluma tree sprout and yield . Moreover, Serrano et al.  reported that the light pruning increased the number of productive branches and number of fruits per branch of guava cv. Paluma. Pruning and hydrogen cyanamide were found to modify the production curve of guava . Moreover, Vazquez et al.  promoted cropping of guava by pruning and ethephone at600 ppm. Urea or NAA or Ethephon has been applied to guava trees in a vigorous vegetative state of growth to change yield patterns [7,8]. Singh et al.  indicated an increase in yield of guava by using potassium nitrate. Also, Rabelo et al.  used Ethrel for improving fruit set of mango cv. Haden. This study aimed to investigate the influence of pruning severity and spraying potassiumnitrate, ethephon or dormex on inducing vegetative growth and fruiting of guava trees. MATERIALS AND METHODS The experiment was carried out during two successive seasons, 2005 and 2006 on guava trees hybrid I produced by Bakr and Selim  and budded on seedlings of guava and grown at the nursery of the
Corresponding Author: Dr. A.E.A. Shaban, Pomology Department, Faculty of Agriculture, Cairo...