Work

Morphophysiological Responses of Black Pepper to Recurrent Water Deficit

Year: 2022

Type: article

Abstract: Drought is one of the main factors that limit the yield of black pepper worldwide. However, the response mechanisms to recurrent water deficit are still unknown. For this reason, the objective of this study was to evaluate the effects of recurrent water deficit on the morphophysiological characteristics of black pepper, as well as to identify the characteristics that are related to the tolerance of ‘Bragantina’ black pepper ( Piper nigrum L.) to drought. 12-month-old plants grown in an 8-L pot were submitted to three cycles of water deficit, with phases of dehydration and rehydration. The study was conducted in a randomized block design, with three replications of 10 plants. Gas exchange was monitored throughout the three cycles of water deficit and leaf water potential, carbohydrates, anatomy, leaf attributes and plant development were evaluated after the third cycle. Data were submitted to analysis of variance and means were compared by the Tukey test at 5% probability (p<0.05). At 14 days of water deficit, there was a reduction in stomatal conductance, photosynthetic rate, transpiration, carboxylation efficiency and leaf water potential. However, an increase in the ability to tolerate stress was observed with each new water restriction, with an increase in water use efficiency. Internal carbon concentration, leaf temperature and root starch content increased with drought. The leaves that developed during the water deficit cycles had an increase in the abaxial epidermis, in the number and length of bundles, in the thickness of the midrib and in stomatal density. However, there was a reduction in the number of xylem vessels. The water deficit cycles provided an increase in phloem length and in the thickness of the periderm of the roots. Nonetheless, it reduced cortex thickness. It was possible to observe an increase in turgid mass, leaf dry matter, leaf mass per area and sclerophyll index in plants submitted to the cycles of drought and rehydration, besides a reduction in specific leaf area, plant height and number of leaves. The main mechanisms involved in ‘Bragantina’ tolerance responses to water deficit were the increase in the thickness of the abaxial epidermis of the leaf, together with the increase in stomatal density, greater presence of fine roots, increase in periderm thickness and starch accumulation in the roots. Despite these readjustments, the plants were not able to resume their vegetative growth after 72 hours of rehydration. However, they recovered gas exchange and leaf water potential.

Source: Photosynthetica

DOI: 10.2139/ssrn.4183213