FORCED PRODUCTION OF GUAVA UNDER GREENHOUSE

Abstract

The harvest of fruit crops takes place at a definite time of the year, which causes excess of fruit, lowering sell prizes; therefore, it is required to force the fruit production out of season or habitat. In order to study the effect of potassium nitrate, ammonium nitrate, Ethrel and water stress upon the vegetative an reproductive growth of guava (Psidium guajava L.) under greenhouse, an experiment was carried out. Previous to budbreak the vegetative growth of secundary branches was between 2 to 4 cm, while after the budbreak, the branches grew 3 to 9 cm, having the largest increase with 10 weekly foliar sprays of amonium nitrate (10 g L-1, each). The largest amount of branches and sprouts, flowers and fruits were also obtained with that treatment, which produced twice as much as the other treatments and ten or more times more than the control. The highest reproductive growth was associated with higher foliar concentrations of total and reduced nitrogen. The fruit harvest was on new shoots in all of the treatments, except for that with Ethrel (1mL L-1) and foliar KNO3 (40 g L-1) where 60 % of the harvest was on branches. Therefore, the production of guava can be forced with foliar sprays of ammonium nitrate, as an alternative of the water stress treatment applied in the production areas. However, it is necessary to determine optimum doses and costs.