Physiological quality of seed and seedling performance of crambe genotypes under water stress

Abstract

A B S T R A C TWater stress is a condition that causes physiological changes in different species and even genotypes of the same species. One of the osmotic agents most used to simulate this condition is polyethylene glycol 6000. The aim of this study was to evaluate the effects of water stress on the physiological quality of seeds and performance of seedlings of crambe genotypes. A completely randomized design was used, in a factorial scheme with two genotypes (one cultivar and one line) and five osmotic potentials simulated with aqueous solutions of polyethylene glycol 6000 (control = 0, -0.25, -0.50, -1.0, -1.50 MPa), with four replicates of 50 seeds per treatment. The effects of the treatments were evaluated by means of germination, first count, germination speed index and fresh and dry matter of seedlings. The physiological quality of seeds and the performance of crambe seedlings are negatively affected under water stress from -0.25 MPa on. Seeds of the genotype FMSCR 1101 have greater tolerance to drought stress, regardless of the osmotic potential used.Qualidade fisiológica de sementes e desempenho de plântulas de genótipos de crambe sob estresse hídrico R E S U M O O estresse hídrico é uma condição que provoca alterações fisiológicas em diversas espécies e até mesmo em genótipos de uma mesma espécie. Um dos agentes osmóticos mais utilizados para simular esta condição é o polietilenoglicol 6000. Objetivou-se, com este trabalho avaliar os efeitos do estresse hídrico na qualidade fisiológica de sementes e no desempenho de plântulas de genótipos de crambe. Utilizou-se o delineamento experimental inteiramente casualizado em esquema fatorial com dois genótipos (uma cultivar e uma linhagem) e cinco potenciais osmóticos simulados com soluções aquosas de polietilenoglicol 6000 (testemunha = 0; -0,25; -0,50; -1,0; -1,50 MPa), em quatro repetições de 50 sementes por tratamento. Os efeitos dos tratamentos foram avaliados por meio dos testes de germinação, primeira contagem de germinação, índice de velocidade de germinação, matéria fresca e matéria seca de plântulas. A qualidade fisiológica das sementes e o desempenho das plântulas de crambe são afetados negativamente sob estresse hídrico a partir de -0,25 MPa. Sementes do genótipo FMSCR 1101 apresentam maior tolerância ao estresse hídrico, independente do potencial osmótico utilizado.

Germination and Seedling Growth of Genotypes Crambe abyssinica Submitted to Water Deficit

“…Rapid germination generally corresponds to seed vigor, leading to faster emergence of seedlings in the field (Marcos-Filho, 2015). In this study, the higher GSI observed for the FMS CR 1203 genotype suggests higher probability that the seeds reached the next phase of the biocycle (Oliveira et al, 2015), because an increase in the GSI under water deficit conditions indicates less susceptibility to pathogens, insects and other pests (Machado et al, 2017), increasing the success of seedling development.…”

“…These studies have the objective of improving the establishment of crops in the field. Machado et al (2017) observed a higher germination rate, germination first count, fresh and dry matter in Crambe abyssinica (Hochst.) FMS CR 1101 genotype submitted to different osmotic potentials induced by polyethylene glycol 6000 (PEG 6000), which was attributed to higher tolerance to water deficit compared with the FMS Brilhante genotype.…”

“…Water deficit is one of the most important and complex environmental factors limiting the germination of seeds (Viçosi et al, 2017) and development of seedlings (Machado et al, 2017). In seeds, water deficit reduces the turgor pressure, negatively affecting the expansion and growth of cells (Bewley & Black, 1994), reducing the availability of oxygen, gas exchanges and synthesis of enzymes and hormones for digestion, translocation and assimilation of reserves (Marcos-Filho, 2005), resulting in a reduced germination speed index (GSI) (Kader & Jutzi, 2002).…”

“…In seeds, water deficit reduces the turgor pressure, negatively affecting the expansion and growth of cells (Bewley & Black, 1994), reducing the availability of oxygen, gas exchanges and synthesis of enzymes and hormones for digestion, translocation and assimilation of reserves (Marcos-Filho, 2005), resulting in a reduced germination speed index (GSI) (Kader & Jutzi, 2002). This exposes the seeds to the action of pathogens and attacks by insects and other pests (Machado et al, 2017). Water deficit also causes an increase in the dry weight of embryos, due to the need for osmotic adjustment, associated with the accumulation of compatible solutes (Gill et al, 2003).…”

“…Several studies have investigated the germination of seeds submitted to different osmotic potentials, to screen for genotypes that are tolerant to water deficit (Machado et al, 2017;Viçosi et al, 2017;Paiva et al, 2018). These studies have the objective of improving the establishment of crops in the field.…”