Caracterização das respostas morfofisiológicas de cultivares de pimenteira-do-reino submetido ao déficit hídrico recorrente

Abstract

The water deficit is a recurring event in the development of the plant. The increased d intensity causes the reprogram plants in the physiological, anatomical and metabolic processes during drought. For this reason, understanding the response mechanisms and levels of tolerance to recurrent water deficit is essential to develop efficient propagation and management strategies. Thus, two works were developed. The first entitled “How do Piper cultivars respond to recurrent water deficit?”, And the second “Morphophysiological changes improve the response to recurrent water deficit?”. Three Piper cultivars were evaluated nigrum L. (' Kottanadan do Broto Roxo', 'Bragantina' and ' Balankota '), the plants were submitted to three cycles of water deficit, with phases of dehydration and rehydration, and in each cycle gas exchange was evaluated. After the third cycle, vegetative growth, photosynthetic pigment, dry mass, carbohydrates and anatomy were evaluated. Exposure to recurrent water deficit events caused changes in gas exchange parameters, carbohydrate allocation, vegetative development, photosynthetic pigment content, anatomy, and dry mass accumulation and allocation. The cultivars reduced the photosynthetic rate, stomatal conductance and transpiration, and increased the water use efficiency, with increased tolerance time after each recurrent water deficit cycle, but with different effects on development. ' Balankota ' maintained photosynthetic rates for longer when subjected to recurrent water deficit and maintained greater efficiency in the use of water, and although there were readjustments in the allocation of carbohydrates, it did not invest in vegetative development. The ' Kottanadan ' was the first to induce stomatal closure under water deficit, with less stomatal conductance, liquid photosynthetic rate, transpiration and EUA, but with an increase in carbohydrate levels and a faster vegetative growth after each cycle. 'Bragantina' was the one that lessened stomatal conductance, but despite this, it maintained water efficiency similar to ' Balankota ', associated with a higher rate of leaf abscission, allocation of starch in the stem and root and decrease in development vegetative. In addition, the cultivars Bragrantina, kottanadan and Balankota subject to recurring drought alter the anatomical variables. Showing that changes in anatomy contribute significantly to the adaptation of cultivars under recurrent water deficit. We can conclude that the Kottanadan cultivar has drought tolerance characteristics that can be considered in breeding programs and should later be evaluated under field conditions, also considering the reproductive stage to verify the effect on grain production.