Discontinuous hydration improves germination and drought tolerance in Annona squamosa seedlings

José Laurindo Dos Santos Júnior,Rafael Silva Freitas,Elizamar Ciríaco Da Silva

doi:10.33448/rsd-v10i3.13706

José Laurindo Dos Santos Júnior, Rafael Silva Freitas + Show 1 more

Open Access

https://doi.org/10.33448/rsd-v10i3.13706

Copy DOI

Abstract

The aim of this work was to determine if the discontinuous hydration of A. squamosa seeds benefit its seed germination and if the seedlings from these seeds have a greater tolerance to water deficit through the analysis of growth parameters. The experimental design was a completely randomized, in a 4x3 factorial, with four HD cycles in seeds (zero, one, two and three) and three water treatments (control with daily watering, and cycles of five and ten-intervals days between watering). Plant height, stem diameter, number of leaves, dry biomass, root/shoot ratio, leaf area, specific leaf area, and leaf area ratio were evaluated. Discontinuous hydration treatments benefited germination and promoted a better growth of the seedlings under water deficit cycles. The application of three HD cycles increased plant height, stem diameter, number of leaves, leaf area and dry matter of the seedlings compared to the other cycles. On the other hand, water suppression caused a reduction in the growth of A. squamosa, especially at ten-day intervals between watering. HD cycles in the seeds improved drought tolerance in the seedlings, mainly when three HD cycles are applied to the seeds, suggesting this is a good technique to produce seedlings better tolerant to environments with reduced water availability.

Highlights

Drought events that occur in arid and semi-arid regions have intensified due to global warming and intermittent rainfall, which has affected humid and urban environments (Güneralp et al, 2015; Xu et al, 2019)
These seeds were submitted to three hydration and dehydration times as a pre-germinative treatment, corresponding to 36 hours of hydration and 7 hours of dehydration, values obtained after plotting the hydration and drying curves, and their control as being the zero cycle, following the protocols described by Lima et al (2018)
Exposure to the three cycles of hydration and dehydration (HD) promoted an increase in germinability (%G) and emergence rate index (ERI), while reducing the mean germination time (MGT) (Table 1)

Summary

Introduction

Drought events that occur in arid and semi-arid regions have intensified due to global warming and intermittent rainfall, which has affected humid and urban environments (Güneralp et al, 2015; Xu et al, 2019) These events, intense and frequent, accentuate declines on growth and plant yield (Silva et al, 2013; Santos Júnior et al, 2020), with negative consequences for the agricultural sector (Li et al, 2009; Lemos et al, 2014; Güneralp et al, 2015; Ramos et al, 2016). Seed conditioning by hardening, referred to as hydroconditioning, is a simple, safe and inexpensive option that can be used as a pre-germinative treatment (Farooq et al, 2019) This technique consists of successively alternating the hydration and dehydration of the seeds during pre-germination, until they return to their initial weight, before the radicle emission. While hydration stimulates the biochemical processes that culminate in germination, dehydration stops them (Meiado, 2013)

Objectives

Methods

Results

Conclusion