Identification of Sorghum (Sorghum bicolor (L.) Moench) Genotypes with Potential for Hydric and Heat Stress Tolerance in Northeastern Mexico.

Marisol Galicia-Juárez,Sugey Ramona Sinagawa-García,Rodrigo Flores-Garivay,Raúl Enrique Valle-Gough,Francisco Zavala-García,Adriana Gutiérrez-Diez,María Eugenia Cisneros-López,Héctor Williams-Alanís,Jesús Santillano-Cázares

doi:10.3390/plants10112265

Abstract

Sorghum (Sorghum bicolor (L.) Moench) is cultivated in regions with frequent drought periods and high temperatures, conditions that have intensified in the last decades. One of the most important photosynthetic components, sensible to hydric stress, is maximum quantum yield for photosystem II (PSII, or Fv/Fm). The objective of the present study was to identify sorghum genotypes with tolerance to hydric and heat stress. The treatments were hydric status (hydric stress or non-hydric stress (irrigation)), the plant’s developmental stages (pre or post-anthesis), and six genotypes. The response variables were Fv/Fm; photosynthetic rate (PN); stomatal conductance (gs); transpiration rate (E); relative water content (RWC); damage to cell membrane (DCM) at temperatures of 40 and 45 °C; and agronomic variables. The experiment was conducted in pots in open sky in Marín, N.L., in the dry and hot northeast Mexico. The treatment design was a split–split plot design, with three factors. Hydric stress diminished the functioning of the photosynthetic apparatus by 63%, due to damage caused to PSII. Pre-anthesis was the most vulnerable stage to hydric stress as it decreased the weight of grains per panicle (85%), number of grains per panicle (69%), and weight of 100 grains (46%). Genotypes LER 1 and LER 2 were identified as tolerant to hydric stress, as they had lower damage to PSII; LER 1 and LEB 2 for their superior RWC; and LER 1 as a thermo tolerant genotype, due to its lower DCM at 45 °C. It was concluded that LER 1 could have the potential for both hydric and heat stress tolerance in the arid northeast Mexico.

Highlights

3 of 16 irrigat irrigation and 70.3% under hydric stress; post-anthesis, soil humidity was significant among treatments, recording mean values of 84.7%across under irrigation and 76.4%
Student’s t-test for soil humidity recorded a significant difference at the pre-anthesis stage, with mean values of 91.2% under irrigation and 70.3% under hydric stress; post-anthesis, soil humidity was significant among treatments, recording mean values of 84.7% under irrigation and 76.4% under hydric stress
Seed yield related variables were more affected by hydric stress pre-anthesis

Summary

Introduction

Sorghum is a crop adapted to dry climates, hydric stress is considered the most important abiotic limiting factor for growth and productivity [9,10,11,12]. This negative effect can be mitigated through genetic improvement, taking advantage of the genetic variability of the species through tolerant germplasm evaluation and selection [13,14,15]. To achieve such goal, is important to understand the physiological responses caused by drought and high temperatures [1,10,16,17]

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Conclusion