Respostas fisiológicas ao déficit hídrico em duas cultivares enxertadas de seringueira ("RRIM 600" e "GT 1") crescidas em campo

Abstract

During their life cycle, plants growing under field condition are subject to periods of air and soil water deficits. In this study was evaluated the performance of two scion cultivar of rubber tree ('RRIM 600' and 'GT 1') growing in São José do Rio Preto, SP, with and without water supplementation since the age of 4 months. The maximum resistance to the uninterrupted dry period, considered when net photosynthesis was ceased, was 17 and 20 days, respectively. Thirty-three days later the water stress was ceased, the gas exchange recovery for both cultivars were quite similar, but just the intercellular carbon dioxide concentration returned to similar values of the control group. Only the relative increment of leaf area to 'GT 1', and plant height of 'RRIM 600' was similar to the control group (P=0.05). The light curve response showed, for both clones, decrease of the compensation irradiance and photosynthetic rate (P=0.05). Although partial, the best recovery after water stress was observed for 'GT 1'.