Resposta ecofisiológica de plantas de Solanum sessiliflorum Dunal submetidas a supressão hídrica seguida por reidratação

Abstract

Plants are sessile organisms that cannot move when cope with adverse conditions. Such conditions are commonly referred as stresses. Among a range of environmental stress, water shortage is considered the main environmental limiting factor in the productivity of species of economic interest and/or ecological system. That said, the aim of this work was to investigate the effects of water shortage followed by recovery under morpho-physiological aspects in plants of ethovariety 1 of Solanum sessiflorum Dunal. The experiment was conducted in a greenhouse in the Institute of Education, Agriculture and Environment of Federal University of Amazonas, Campus Humaitá. Solanum sessiliflorum plants were clustered in two groups: (a) control plants: plant daily irrigated maintained close to filed capacity and (b) plants stressed: plants under water shortage during seven days followed by recovery for seven additional days. Biometric and physiological analyzes were performed in order to understand how this culture responds to those conditions. The effect of water shortage was evaluated in Solaunum sessiliflorum plants by following reduction in the leaf water status measuring WRC. It was observed that from the fifth day of water deprivation WCR level reduced when compared with daily plants reaching the lowest level up to seventh day. Notwithstanding, it was also observed that the water status is restored as soon as water is available. Water shortage impacted severely plant phenotype as well as its growth and accumulation of biomass. The growth (length and width) of the leaf primordium of Solanum sessiliflorum was limited under water deprivation. However, after rehydration, the leaf growth was restored reaching in the end of leaf expansion values similar to those of plants daily irrigated. Although dry mass (DM) of the stem showed none difference under water deficit, it was seen that leaf and root DM showed a reduction in such condition. In turn, no significant difference for the shoot / root ratio was found. Regarding to physiological parameters, it was also observed, for the fluorescence analyzes significant reduction in the values of Fv/Fm on the seventh day and one day of water limitation and rehydration, respectively. qP showed a reduction from the third day of water limitation, reaching a lower value on the seventh day without irrigation, however, these values were equaled with the prolonged rehydration. The NPQ values were higher in plants stressed on the third and fifth days of absence of irrigation, suggesting a photoprotective effect causeb by water shortage. Moreover, no significantly difference in plants rehydrated was found when compared with daily irrigated plants group. Water deprivation also negatively affected gas exchange (An, gs and Ci). When taken together, these findings of water shortage suggesting for a stomatal limitation of photosyntheiss followed by a biochemical limitation of carbono assimilation rate when irrigation is restored. Thus, the results stated in this work show a putative resilience of Solaun sessiliflorum throughout seven days of water deprivation. In the condition tested in this work, Solanum sessiliflorum stated key morpho-physiological features of phenotype plasticity water stress-related.