Influência dos ciclos de rega na anatomia e metabolismo bioquímico foliar de Cenostigma pyramidale (Fabaceae)

Abstract

The species Cenostigma pyramidale is especially important in the ecological aspect and little explored in the economic and environmental sphere, in view of its great potential, besides being used for timber and medicinal purposes is a pioneer species with high potential for the recovery of degraded areas. This work aims to evaluate the physiological and anatomical responses of the leaves of one of these species, Cenostigma pyramidale under irrigation cycles and submitted to water deficit. The plants were submitted to four experimental groups, during the growing period, counting ten individuals per treatment: Control - daily watering; RD - daily watering; R7 - watering 1x in 7 days; R14 - watering 1x in 14 days. After five months of growth in the greenhouse, the individuals were submitted to a period of water deficit, where there was complete suspension of water, and then underwent recovery, from which five individuals from each treatment were collected at the end of each period for biochemical analysis and leaf anatomy. To determine the periods, analysis of relative leaf water content (RWC) and soil moisture was performed. It was observed that plants from more severe treatments proved to be more resistant, in general, to maximum stress, anatomically and biochemically, investing in adaptations such as tannins, crystals and stomatal chambers, still showing expressive photosynthetic rates, indicating that pre-contact with short intervals of water shortage affects leaf storage responses during a prolonged water shortage. The most efficient use of resources was seen in the treatment that was subjected to irrigation every fourteen days (R14), which showed a high rate of total free amino acids, proteins, higher rate of photosynthetic pigments, presence of an abundant palisade parenchyma, while showing a tendency to decrease the volume of the mesophyll, among other adaptations. Thus, with this work it was possible to conclude that previous contact with lack of water positively affects the species Cenostigma pyramidale, generating more efficient responses and providing important anatomical and biochemical changes in its leaves.