Guava is an important fruit crop in Egypt. Guava trees usually give the heaviest yield in summer which is sold at little price. Compared to summer crop, winter crop is much superior in quality and fetch premium price. Thus, the main goal of this study was to regulate the guava tree inflorescence to give winter yield by inhibition of flower bud differentiation and flowering in spring, promote the flowering in autumn and produce winter crop with high quality. To fulfill this aim guava trees were sprayed with Gibberellic acid (GA3 ) at 100 or 200 ppm at three dates (15th, 22ed February and 1st March) plus Paclobetrazol (PP333) at 50 or 100 ppm in the following June 15th.
Anatomical studies and the obtained results showed that spraying guava trees with GA3 at 100 or 200 ppm on 15th or 22ed February prevented flower bud induction and flowering in spring. Spraying the same trees with PP333 at 50 or 100 ppm following June 15th promoted flowering in late summer and gave winter yield with high quality .