Evaluation of chemical desiccation as a selection technique for drought resistance in a dryland wheat breeding program

1993 ◽  
Vol 44 (8) ◽  
pp. 1683 ◽  
Author(s):  
KL Regan ◽  
BR Whan ◽  
NC Turner

Previous studies have shown that some chemical desiccants and senescing agents, when applied to adequately watered cereals 10 to 14 days after anthesis, can be used to select lines with stable grain size (kernel weight) under post-anthesis water deficits. The present study evaluated the potential of one of these chemicals, potassium iodide (KI), to select for this character in a dryland wheat breeding program. Ninety-six F2-derived lines grown in the F6and F7 generations and 11 cultivars of wheat (Triticum aestzvum L.) were grown in two experiments at two medium-rainfall sites in 1988 and 1989 and sprayed with a 0.3% solution of KI when the grains had developed one-third in the lemma. Reductions in grain yield and thousand kernel weight due to treatment with KI were greater in 1988 than in 1989, probably due to the higher growing-season rainfall in that year. The reduction in grain yield as a result of desiccation was greater than the reduction in thousand kernel weight, but the correlation between the two was low (0.09 to 0.58) and non-significant in five out of the eight comparisons. There were considerable differences among genotypes in response to the desiccation treatment in the wetter 1988. Genetic coefficients of variation ranged from 5.6 to 12.9% for yield and 2.5 to 9.5% for thousand kernel weight. The ratio of the variance component estimates for the interaction between genotypes and desiccation treatment to the variance component estimates for genotypes was generally less than one. However, genetic differences in response to the desiccation treatment could be demonstrated in some experiments, particularly at one site and in the wetter of the two years. We conclude that the chemical desiccation technique can be used to select for post-anthesis drought resistance in a dryland breeding program. However, there are some limitations to the technique, and selection needs to be confined to wetter sites and seasons.

2020 ◽  
Author(s):  
Yan Yang ◽  
Smit Dhakal ◽  
Chenggen Chu ◽  
Shichen Wang ◽  
Qingwu Xue ◽  
...  

AbstractTwo drought-tolerant wheat cultivars, ‘TAM 111’ and ‘TAM 112’, have been widely grown in the Southern Great Plains of the U.S. and used as parents in many wheat breeding programs worldwide. This study aimed to reveal genetic control of yield and yield components in the two cultivars under both dryland and irrigated conditions. A mapping population containing 124 F5:7 recombinant inbred lines (RILs) was developed from the cross of TAM 112/TAM 111. A set of 5,948 SNPs from the wheat 90K iSelect array and double digest restriction-site associated DNA sequencing was used to construct high-density genetic maps. Data for yield and yield components were obtained from 11 environments. QTL analyses were performed based on 11 individual environments, across all environments, within and across mega-environments. Thirty-six unique consistent QTL regions were distributed on 13 chromosomes including 1A, 1B, 1D, 2A, 2D, 3D, 4B, 4D, 6A, 6B, 6D, 7B, and 7D. Ten unique QTL with pleiotropic effects were identified on four chromosomes and eight were in common with the consistent QTL. These QTL increased dry biomass grain yield by 16.3 g m−2, plot yield by 28.1 g m−2, kernels spike−1 by 0.7, spikes m−2 by 14.8, thousand kernel weight by 0.9 g with favorable alleles from either parent. TAM 112 alleles mainly increased spikes m−2 and thousand kernel weight while TMA 111 alleles increased kernels spike−1, harvest index and grain yield. The saturated genetic map and markers linked to significant QTL from this study will be very useful in developing high throughput genotyping markers for tracking the desirable haplotypes of these important yield-related traits in popular parental cultivars.


2021 ◽  
Author(s):  
Karansher S Sandhu ◽  
Meriem Aoun ◽  
Craig Morris ◽  
Arron H Carter

Breeding for grain yield, biotic and abiotic stress resistance, and end-use quality are important goals of wheat breeding programs. Screening for end-use quality traits is usually secondary to grain yield due to high labor needs, cost of testing, and large seed requirements for phenotyping. Hence, testing is delayed until later stages in the breeding program. Delayed phenotyping results in advancement of inferior end-use quality lines into the program. Genomic selection provides an alternative to predict performance using genome-wide markers. Due to large datasets in breeding programs, we explored the potential of the machine and deep learning models to predict fourteen end-use quality traits in a winter wheat breeding program. The population used consisted of 666 wheat genotypes screened for five years (2015-19) at two locations (Pullman and Lind, WA, USA). Nine different models, including two machine learning (random forest and support vector machine) and two deep learning models (convolutional neural network and multilayer perceptron), were explored for cross-validation, forward, and across locations predictions. The prediction accuracies for different traits varied from 0.45-0.81, 0.29-0.55, and 0.27-0.50 under cross-validation, forward, and across location predictions. In general, forward prediction accuracies kept increasing over time due to increments in training data size and was more evident for machine and deep learning models. Deep learning models performed superior over the traditional ridge regression best linear unbiased prediction (RRBLUP) and Bayesian models under all prediction scenarios. The high accuracy observed for end-use quality traits in this study support predicting them in early generations, leading to the advancement of superior genotypes to more extensive grain yield trailing. Furthermore, the superior performance of machine and deep learning models strengthen the idea to include them in large scale breeding programs for predicting complex traits.


PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0237293
Author(s):  
Yan Yang ◽  
Smit Dhakal ◽  
Chenggen Chu ◽  
Shichen Wang ◽  
Qingwu Xue ◽  
...  

Two drought-tolerant wheat cultivars, ‘TAM 111’ and ‘TAM 112’, have been widely grown in the Southern Great Plains of the U.S. and used as parents in many wheat breeding programs worldwide. This study aimed to reveal genetic control of yield and yield components in the two cultivars under both dryland and irrigated conditions. A mapping population containing 124 F5:7 recombinant inbred lines (RILs) was developed from the cross of TAM 112/TAM 111. A set of 5,948 SNPs from the wheat 90K iSelect array and double digest restriction-site associated DNA sequencing was used to construct high-density genetic maps. Data for yield and yield components were obtained from 11 environments. QTL analyses were performed based on 11 individual environments, across all environments, within and across mega-environments. Thirty-six unique consistent QTL regions were distributed on 13 chromosomes including 1A, 1B, 1D, 2A, 2D, 3D, 4B, 4D, 6A, 6B, 6D, 7B, and 7D. Ten unique QTL with pleiotropic effects were identified on four chromosomes and eight were in common with the consistent QTL. These QTL increased dry biomass grain yield by 16.3 g m-2, plot yield by 28.1 g m-2, kernels spike-1 by 0.7, spikes m-2 by 14.8, thousand kernel weight by 0.9 g with favorable alleles from either parent. TAM 112 alleles mainly increased spikes m-2 and thousand kernel weight while TMA 111 alleles increased kernels spike-1, harvest index and grain yield. The saturated genetic map and markers linked to significant QTL from this study will be very useful in developing high throughput genotyping markers for tracking the desirable haplotypes of these important yield-related traits in popular parental cultivars.


2020 ◽  
Vol 11 ◽  
Author(s):  
Philomin Juliana ◽  
Ravi Prakash Singh ◽  
Hans-Joachim Braun ◽  
Julio Huerta-Espino ◽  
Leonardo Crespo-Herrera ◽  
...  

PLoS ONE ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. e0221603 ◽  
Author(s):  
Dennis N. Lozada ◽  
Brian P. Ward ◽  
Arron H. Carter

2019 ◽  
Author(s):  
Dennis N. Lozada ◽  
Arron H. Carter

AbstractIncreased genetic gains for complex traits in plant breeding programs can be achieved through different selection strategies. The objective of this study was to compare potential gains for grain yield in a winter wheat breeding program through estimating response to selection R values across several selection approaches including phenotypic (PS), marker-based (MS), genomic (GS), and a combination of PS and GS. Five populations of Washington State University (WSU) winter wheat breeding lines evaluated from 2015 to 2018 in Lind and Pullman, WA, USA were used in the study. Selection was conducted by selecting the top 20% of lines based on observed yield (PS strategy), genomic estimated breeding values (GS), presence of yield “enhancing” alleles of the most significant single nucleotide polymorphism (SNP) markers identified from genome-wide association mapping (MS), and high observed yield and estimated breeding values (PS+GS). Overall, PS compared to other individual strategies showed the highest response. However, when combined with GS, a 23% improvement in R for yield was observed, indicating that gains could be improved by complementing traditional PS with GS. Using GS alone as a selection strategy for grain yield should be taken with caution. MS was not that successful in terms of R relative to the other selection approaches. Altogether, we demonstrated that gains through increased response to selection for yield could be achieved in the WSU winter wheat breeding program by implementing different selection strategies either exclusively or in combination.


2009 ◽  
Vol 7 ◽  
pp. 63-69
Author(s):  
PCP Chaurasia ◽  
E Duveiller

An experiment was conducted at agronomy farm of Agriculture research Station, Tarahara,Nepal for three consecutive years viz 2000/2001,2001/2002, and 2002/2003 to evaluate theeffects of different cultural practices on leaf blight diseases of wheat caused by Bipolarissorokiniana under terai conditions. The experiment was conducted in factorial RandomizedComplete Block Design with four replications. Four factors, two wheat verities RR-21 andNepal 297,two number of irrigations (two and three irrigations), two doses of Nitrogen fertilizerviz. 60kg N/ha and 120 kg N/ha and two dates of sowing of wheat were examined. Differentyield components, grain yield (kg/plot) and disease severity were recorded to judge the effects ofthese factors on severity of leaf blight of wheat. Nepal Line 297 had significantly less AUDPCbased on flag leaf infection and whole plan as compared to RR-21. Number of irrigations had nosignificant effect on AUDPC, as there was frequent rain during experimental period. Doses ofNitrogen fertilizer had significant effect on AUDPC based on flag leaf infection. It was higher incase of 60 kg N/ha. The third week of November sowing of wheat had lower value of AUDPCas compared to December sowing. Plant height, panicle lengths were highly significantly higherin case of RR-21 as compared to Nepal-297. Thousand kernel weight, and grain yield kg/ha weresignificantly higher in Nepal-297. All agronomic parameters except thousand kernel weight andnumber of tillers/plan were significantly higher in 120kg N/ha. The third week of Novembersowing of wheat had less plant height and panicle length, higher thousand kernel weight andmore grain yield. Leaf blight severity was highly significantly less in case of Nepal-297. Dosesof Nitrogen fertilizer had significant effect on plant height, panicle length, thousand kernelweight, percentage flag leaf infection and AUDPC based on flag leaf infection. Based on theresults of three years of experimentations, it can be concluded that Nepal-297 had less disease,number of irrigations had no effect on disease severity, higher doses of nitrogen fertilizer hadless flag infection and late sowing of wheat also had less disease. Numbers of irrigation's effectswere inconclusive as there were frequent rains during experimentation period. Based on aboveconclusion, it is recommended that growing wheat verity like Nepal-297, use of higher doses ofnitrogen fertilizer and sowing of wheat / first week of Dec help in minimizing the severity of leafblight. However late sowing had lowered grain yield.Key words: AUDPC; culture practices; disease management; leaf blightDOI: 10.3126/narj.v7i0.1870Nepal Agriculture Research Journal Vol.7 2006 pp.63-69


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