Multi-Environment Screening of Durum Wheat Genotypes for Drought Tolerance in Changing Climatic Events

Afef Othmani,Jaime A. Teixeira da Silva,Sourour Ayed,Imen Bouhaouel

doi:10.3390/agronomy11050875

Abstract

Durum wheat is the most widely grown cereal in Tunisia, but its production is threatened by drought, which is exacerbated by climate change. This study aimed to identify drought-tolerant durum wheat genotypes from five modern varieties and six landraces in a multi-environment trial at two sites (Kef and Siliana, Tunisia) during three growing seasons under rainfed and irrigated conditions. Six drought tolerance indices (mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), tolerance index (TOL), stress tolerance index (STI), and yield stability index (YSI)) were used to evaluate the 11 genotypes. The environment was the dominant source of variation for grain yield (GY; 94.27%), followed by the environment × genotype interaction (4.06%) and genotype (1.65%). Cluster analysis based on GY identified four environment-based groups with distinct water treatments, extreme minimum/maximum temperatures, and rainfall. Principal component analysis and a correlation matrix revealed that drought tolerance indices significantly correlated with GY in non-stressed and stressed conditions and could be separated into four groups. Based on STI, MP, and GMP, G6 and G8 (landraces) were the most drought-tolerant genotypes attaining high GY in both conditions. TOL was able to discriminate G1, G3, and G5 (modern varieties) as well as drought-susceptible genotypes, all of which were suitable for irrigation. Genotypes G7, G9, G10, and G11 (landraces), which had high SSI and lowest STI, MP, GMP, and YSI values, were susceptible to drought and were thus not suitable for cultivation in both conditions. Finally, G2 and G4 (modern varieties), which had an intermediate rank for different indices, were classified as semi-tolerant or sensitive genotypes. Drought tolerance indices and genotype ranks were helpful tools to screen drought-tolerant genotypes with a large adaptation to a range of environments, namely irrigated and rainfed conditions (landraces G6 and G8), or genotypes with the ability to adapt (modern varieties G1, G3, and G5) to irrigated conditions.

Highlights

Among cereal crops, durum wheat (Triticum durum Desf.) is the 10th most commonly cultivated cereal worldwide and one of the most important food crops in the Mediterranean Rim with an important role in the human diet [1,2]
Several drought tolerance indices (DTIs) that are based on yield under drought and normal conditions have been used to increase selection efficiency and to screen genotypes grown under drought stress
Precipitation and extreme temperature events during the most sensitive period of durum wheat growth from 2007 to 2017 at Kef and Siliana sites are presented in Figures 2 and 3

Summary

Introduction

Durum wheat (Triticum durum Desf.) is the 10th most commonly cultivated cereal worldwide and one of the most important food crops in the Mediterranean Rim with an important role in the human diet [1,2]. By 2030, Tunisia is expected to suffer from an annual average increase in temperature of 1.1 ◦C and an annual acute decrease in precipitation and water resources [6] This will acutely influence rainfed durum wheat, which is the most important cultivated crop in Tunisia representing 54% of the cereal growth area (~1.5 million ha) [18,19] and decreasing yield by almost 30% [8]. Screening durum wheat genotypes for drought tolerance and improving their water use efficiency were useful key tools employed by cereal breeders to increase production and productivity [16,21]. Several drought tolerance indices (DTIs) that are based on yield under drought and normal conditions have been used to increase selection efficiency and to screen genotypes grown under drought stress. The selection of different genotypes grown under environmental stress was one of the main challenges for plant breeders who exploited genetic variation to improve drought-tolerant varieties [36]

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Results

Discussion

Conclusion