TRANSMISSÃO DE SINAL DE FALTA DE ÁGUA ENTRE PLANTAS: EFEITOS SOBRE A TEMPERATURA E A PRESSÃO DE TURGOR FOLIAR

Abstract

A growing body of evidence shows that plants anticipate responses of stress as a result of signals transmitted by neighboring plants. Transmit signal of lack of water between plants is a factor that adds complexity in the dynamics of populations, communities and ecosystems. Knowing more about this ability of plants can be useful for agriculture, mainly agro-forestry systems, and for reforestation efforts. By this way, this job was done to try to find more evidences of lack of water signaling transmission. To do this, stomata aperture related parameters (leaf temperature and leaf turgor pressure) were used to find possible effects of plants under lack of water on their neighborhood. Stomatal aperture, leaf temperature and leaf turgor pressure are parameters that indicates plant water status. Two experiments were done, one measured leaf temperature, and other leaf turgor pressure. Glycine max was used as experimental model. The seedlings roots were pruned, leaving only two roots similar per plant ("split-root"). The split-root plants were arranged in sets, with 4 pots and 3 plants (with each plant roots was divided into two pots). To induce sudden lack of water, mannitol solution was used (-2MPa), applied in the first pot. Leaf temperature was monitored by thermographic camera, and the leaf turgor was monitored by magnetic probe leaf turgor pressure (ZIM-probe). Data analysis was based on graphic interpretation. Leaf temperature variation was synchronous among plants of each set. The variation of leaf turgor in the day of induction to stress was completely changed from the previous day in half of sets. The sets which turgor variation was changed also showed sync. Environmental conditions, namely air temperature, and air relative humidity, were monitored and showed no correlations with the variation in leaf temperature or leaf turgor pressure. Sync indicates that there was communication. It is possible that lack of water communication among plants increases population stability. Stability in population can increase the fitness. So, it is possible that communication of lack of water among plants is a characteristic that has been shaped by natural selection, and distributed among taxa.