Características fisiológicas e controle do florescimento natural do abacaxizeiro com uso do tiossulfato de prata

Abstract

Pineapple plant has morphological characteristics and physiological mechanisms that minimize loss and increase the efficiency of water use, presents carbon dioxide fixation at night, allowing their stomata to close during the day. For other hand, natural flowering of pineapple plant is an unwanted process. The occurrence of natural flowering may be reduced or eliminated with the use of inhibitors of ethylene action. For that reason, two essays were carried out, being the first one related to pineapple characteristics, and de second one related to inhibition of natural flowering. This study conducted at Experimental area of the Universidade Estadual de Montes Claros, Janaúba campus, aimed to analyze, in the work "I", the liquid photosynthetic assimilation rate (A), internal CO2 concentration (Ci), the efficiency of carboxylation (CE), leaf temperature (TF) and the maximum quantum yield of photosystem II (Fv/Fm) using a Infra-Red Gas Analyzer (IRGA), with measurements every hour during 24 hours in a period of 6 evaluation intervals of 7 days, besides the TDR analyzer to monitor water stress applied. In the work "II", evaluate the effect of silver thiosulfate (STS) in inhibiting the natural flowering of the pineapple plant. This essay was set in a randomized blocks design, in a 4 x 5 factorial scheme, corresponding to four cultivars of pineapple plant (‘IAC Fantástico ', 'Pérola', 'MD2' and 'Vitória') and five doses of silver thiosulfate (0; 0.5; 1; 2 and 3 mmol L-1 ). We applied 50 ml of the solution inside the leaf rosette of pineapple plant with an interval of 15 days, in June and July. We concluded that water stress respectively provided lower rates of liquid photosynthesis assimilation at night. There was diurnal CO2 absorption in water deficit submitted fructification. Water stress did not cause irreversible damage to the photochemical phase in the reproductive stage. The characteristics were evaluated and results have shown that the application of STS in the leaf rosette does not inhibit the pineapple flower differentiation, it increases the fruit diameter and 'D' leaf dry mass, it reduces the pulp pH and does not affect the fruit growing.