Efficiency of drought tolerance indices under different stress severities for bread wheat selection

Abstract

Drought is a world-wide spread problem adversely affecting bread wheat production in rainfed agro-ecosystems. Development and identification of efficient selection criteria for developing drought tolerant wheat varieties with stable and high yield potential is of paramount importance. This study was carried out to evaluate 24 indices for selecting the best high yielding and drought tolerant cultivars, among 40 bread wheat genotypes, under four levels of stress intensities: no stress, mild (0.25, 0.35) and severe (0.57). The mean productivity (MP), modified stress tolerance index (MSTIk), superiority index (Pi), mean relative performance (MRP), relative efficiency index (REI), geometric mean productivity (GMP), stress tolerance index (STI), harmonic mean (HARM) and relative decrease in yield (RDY) showed a high power of discrimination among genotypes, and expressed significant correlations with yields under both stress and non-stressed conditions at all stress intensities. This group of indices was capable to select the highest mean yield associated with the least mean variance at 20 % selection pressure. However, as the stress intensity became greater (>35 %), the efficiency of these indices decreased, especially at high stress intensity (57%), where only Pi and MP were still able to target the highest performances. MRP, REI, GMP, RDY and STI can be used interchangeably. Based on GGE analysis, the best performing genotypes were AUS30355, followed by Gladius, Amir-2 and AUS30354 that showed high yield and stability across all the environments. These genotypes are recommended for direct release and/or for use as parents in the breeding programs.

Drought tolerance indices for selection of drought tolerant, high yielding upland rice genotypes

“…This study revealed a decrease in mean grain yield of 34% in the drought-stressed main plot in which soil moisture declined to 50% field capacity level in the post flowering stage of the rice life cycle, relative to the unstressed main plot treatment in which irrigation ensured field capacity through until harvest. Decrease of grain yield due to drought stress in cereal crops has been reported previously by many workers (Rahman et al, 2002;Yue et al, 2006;Golabadi et al, 2006;Moosavi et al, 2008;Dadbakhsh et al, 2011;Farshadfar and Elyasi, 2012;Dixit et al, 2014;Bennani et al, 2017). The drought stress-induced grain yield reduction reported here was of moderate level.…”

“…Results in this study indicated a positive and highly significant correlation between YP and YS under moderate/0.34 stress level, suggesting that genotypes that showed high grain yield under non-stressed condition also demonstrated high yield under stressed condition. A positive correlation between YP and YS has also been reported in earlier studies (Moosavi et al, 2008;Dadbakhsh et al, 2011;Naghavi et al, 2013;Bennani et al, 2017). The drought indices STI, GMP, MRP, HARM, MP, REI and ATI also showed highly significant correlations with YP and YS, which suggests that the drought indices are able to identify high yielding genotypes under non-stressed and stressed conditions.…”

“…A previous study by Farshadfar and Elyasi (2012) successfully used a mean-rank method in combination with correlation analysis, and Principal Component Analysis to select for drought tolerant genotypes of bread wheat landraces. Drought indices such as STI, MP, GMP, MRP, HARM, RDI, ATI, REI, and MISTIK1 have also been reported to be effectively used to select drought tolerant, high yielding genotypes in various crops (Dadbakhsh et al, 2011;Farshadfar and Elyasi, 2012;Naghavi et al, 2013;Ali and El-Sadek, 2016;Bennani et al, 2017). Results in this study indicated a positive and highly significant correlation between YP and YS under moderate/0.34 stress level, suggesting that genotypes that showed high grain yield under non-stressed condition also demonstrated high yield under stressed condition.…”

“…In summary, to date, more than 20 indices have been employed for selection of drought-tolerant varieties, with varying degree of effectiveness depending on the particular crop species. Among these, STI, SSI, MP, MRP, HARM, REI, ATI, GMP, MSTIK1, MSTIK2, SNPI, SSPI, YI, RDI, and RDY have previously been reported to be the most suitable indices for various crops (Naghavi et al, 2003;Sio-Se et al, 2006;Moosavi et al, 2008;Bahar and Yildirim, 2010;Golbashy et al, 2010;Dadbakhsh et al, 2011;Farshadfar and Elyasi, 2012;Mau et al, 2014;Ali and El-Sadek, 2016;Bennani et al, 2017) but these have not been assessed in upland rice. Thus, the purposes of the study reported in this paper were (1) to assess the effectiveness of drought tolerance indices for selection of drought tolerance in upland rice, and (2) to determine the most suitable index for identifying drought tolerant, high-yielding upland rice genotypes.…”

Agronomic performance and drought tolerance level of sweet potato hybrids grown in Kupang, East Nusa Tenggara, Indonesia

“…Substantial mean yield differences among genotypes under different irrigation levels indicate the presence of interaction effect of genotype by environment, where the expression of genes controlling tuber yield trait depends significantly on the genotype and water level condition. There was a significant difference in the overall mean tuber yield of all genotypes under no water stress (23.42 t ha -1 ) and water-stressed (7.08 t ha -1 ) conditions, which indicates a very high stress intensity ((1-(Ys/Yp)) (Bennani et al 2017) of 0.70 (within the range of 0.0-1.0). had also observed a dramatic difference of mean tuber yield of local sweet potato from NTT Province under normal and waterstressed conditions of 12.6 t ha -1 and 6.0 t ha -1 , respectively, with a stress intensity of about 0.5.…”