Physiological responses of Triplaris gardneriana Wedd. seedlings (Polygonaceae) under intermittent drought

Elizamar Ciríaco Da Silva,José Roberto Vieira Aragão,Iére Barros Bispo,Islayne Da Cruz Menezes,Hugo Henrique Costa Do Nascimento

doi:10.14808/sci.plena.2021.124901

Elizamar Ciríaco Da Silva, José Roberto Vieira Aragão + Show 3 more

Open Access

https://doi.org/10.14808/sci.plena.2021.124901

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Abstract

Triplaris gardneriana Wedd is a deciduous riparian tree occurring in areas with different climatic conditions in Brazil, from the rainforest to the tropical dry forest. An increase in global temperature and drought events can change the growth pattern and establishment of the species. To evaluate the effects of intermittent drought on the growth of T. gardneriana seedlings, an experiment was performed using seedlings with one month old subjected to three water treatments (daily irrigation as control, and intermittent drought through cycles of water suppression of seven (S7) and 14 days-intervals (S14) between watering. Growth, biomass production and partitioning, relative water content (RWC), the accumulation of organic solutes, protoplasmic integrity and phenotypic plasticity index (PPI) were evaluated for a better understanding about its drought tolerance level. Intermittent drought severely affected plants growth in S14 plants, showing lower plant height, number of leaves, leaf area, and dry biomass. RWC was reduced, while carbohydrates and proline contents increased in response to drought stress. Protoplasmic damage increased electrolyte leakage in plants subjected to severe stress. However, T. garderiana demonstrated moderate tolerance to water deficit. The plastic changes observed were more physiological than morphological. Therefore, T. gardneriana seems to be a moderately tolerant species to intermittent drought.

Highlights

Growth and establishment of seedlings in the environment depend on favorable climate and soil conditions as well as the genetic capacity of species to cope with seasonal changes
No stunting in growth occurred in terms of height, plants cultivated with a 14-day interval between watering (S14) exhibited a significantly lower value in growth beginning from the 29th day after the differentiation of the water treatments (Figure 1A)
Plants grown with a seven-day interval between watering (S7) exhibited similar growth to that found in the control plants (Figure 1A)

Summary

Introduction

Growth and establishment of seedlings in the environment depend on favorable climate and soil conditions as well as the genetic capacity of species to cope with seasonal changes. The seasonally dry tropical forest in Northeastern Brazil, denominated Caatinga, is characterized by low annual rainfall, with irregular rain distribution concentrated in two to three months, followed by a long period of drought, high temperatures and low relative air humidity [3, 4] These conditions generate water deficit in the soil, which is a stress factor for plants that affects growth and development, especially for seedlings in the field [5, 6], which is recognized as the most critical phase to plants establishment. Especially in length, are generally inhibited and some species exhibit changes in the growth pattern as the main adaptive characteristic, such as an increased root system at the expense of shoot growth [4, 9] These changes reduce the loss of water through leaf transpiration and allow the exploration of deeper layers of soil for moisture [7, 10, 11]

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