Breeding for drought tolerance: Direct selection for yield, response to selection and use of drought-tolerant donors in upland and lowland-adapted populations

AbstractThe progress in development and dissemination of drought tolerant lines has been slow as compared to the increasing drought prevalence in the rice growing regions. Significant amount of work has been done in the past on drought resistance traits in rice crop, still the benefit of improved drought tolerant rice cultivars reaching the farmer’s field is not very high and ways to expedite the development of drought tolerant and productive rice cultivars needs to be addressed. In this article, an assessment of easily practicable approach of managed stress screening and prospect of direct selection for yield under drought stress is discussed. Also the large effect yield QTLs identified for grain yield under drought stress field conditions is being reviewed for successful introgression into elite genetic background for developing drought tolerant cultivars with improved yield for the drought prone target environment.

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INHERITANCE OF WEIGHTS OF LAMBS REARED ARTIFICIALLY OR WITH THEIR DAMS

Canadian Journal of Animal Science ◽

10.4141/cjas83-033 ◽

1983 ◽

Vol 63 (2) ◽

pp. 263-268 ◽

Cited By ~ 6

Author(s):

J. N. B. SHRESTHA ◽

H. F. PETERS ◽

D. P. HEANEY

Keyword(s):

Genetic Correlation ◽

Direct Selection ◽

Milk Replacer ◽

Response To Selection ◽

Genetic Response ◽

Artificial Rearing ◽

Solid Diet ◽

Selection For ◽

Heritability Estimates ◽

Age Estimates

This study involved 250 lambs reared artificially with milk replacer and solid diet from 2 to 70 days and 316 lambs creep-fed solid diet and reared with their dams from birth to 70 days. Thereafter, all lambs were retained on solid diet to 140 days of age. Heritability estimates for weights of lambs reared artificially tended to be larger than the corresponding estimates for lambs reared with their dams (P > 0.05). Phenotypic variances of lambs reared with their dams were larger at birth and at 35 days, whereas lambs reared artificially had larger phenotypic variances at 70 and 140 days of age. Estimates of genetic correlation between half-sib family means of lambs reared artificially with corresponding half-sibs reared with their dams ranged from 0.15 to 0.91, suggesting the absence of sire × rearing system interaction. We conclude that greater genetic response to selection for lamb weights at various ages could be achieved from direct selection among lambs reared artificially compared to those reared with their dams. However, in the absence of artificial rearing, prospective breeding stock reared with their dams should be tested for postweaning performance to permit full expression of transmitted sire differences. Key words: Sheep, lamb rearing, heritability estimates, genetic correlation

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Evaluation of advanced back cross lines for drought tolerance in rice (Oryza sativa L.)

INTERNATIONAL JOURNAL OF AGRICULTURAL SCIENCES ◽

10.15740/has/ijas/17-aaebssd/245-251 ◽

2021 ◽

Vol 17 (AAEBSSD) ◽

pp. 245-251

Author(s):

P. Venkata Ramana Rao ◽

M. Girija Rani ◽

K.S.N. Prasad ◽

P. Naga Kumari ◽

B.N.V.S.R. Ravi Kumar ◽

...

Keyword(s):

Drought Tolerance ◽

Oryza Sativa L ◽

Seedling Survival ◽

Direct Selection ◽

Rice Varieties ◽

Back Cross ◽

Drought Tolerant ◽

Wide Range ◽

Drought Conditions ◽

Secondary Traits

Drought is the largest abiotic constraint to rice production which cause significant yield loss depending upon the severity. Development of rice varieties with tolerance to drought and high use water use efficiency is the need of the hour. Despite the importance of drought as major abiotic constraint, the efforts to develop drought tolerant rice varieties are very low. Breeding efforts until recent past were focused on understanding and improvement of secondary traits that are putatively associated with drought tolerance. However, the genetic gain in yield by improvement of secondary traits is very low. Hence, improvement of yield per se under drought conditions will be better solution. Introgression of yield QTLs under drought in the genetic background of high yielding varieties will be helpful to overcome the problem to a certain extent. In the present study, 31 advanced back cross lines (BILs) derived from drought susceptible mega variety Samba Mahsuri (BT 5204) and a drought tolerant tolerant land race Azucena were evaluated under drought. Thirty one advanced back cross inbred lines (BC2F4) lines having yield QTLs viz., qDTY3.1 on chromosome 3 and qDTY2.1 on chromosome 2 were phenotyped under drought conditions. The results suggested that wide range of variation was observed for yield and its component traits in the BILs generated in the background of BPT 5204 and direct selection for yield under water stress coupled with marker assisted screening would help in development of drought tolerant version of mega varieties with improved yield under stress. Thermo tolerance studies indicated that high variability was observed for the BILs in terms of % seedling survival, % reduction in root and shoot growth under stress.

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Genetic Variability And Selection Response To Heat Tolerance Through Membrane Thermostability In Spring Wheat (Triticum Aestivum L)

Bangladesh Journal of Plant Breeding and Genetics ◽

10.3329/bjpbg.v23i2.9320 ◽

1970 ◽

Vol 23 (2) ◽

pp. 15-22

Author(s):

NCD Barma ◽

MA Islam ◽

MA Hakim ◽

DKR Sarker

Keyword(s):

Genetic Variability ◽

Heat Tolerance ◽

Selection Response ◽

Research Centre ◽

Direct Selection ◽

Realized Heritability ◽

Response To Selection ◽

Early Generation ◽

Membrane Thermostability ◽

Selection For

The present investigation was undertaken to study the genetic variability and selection response of heat tolerance measured through membrane thermostability (MTS) in F2 derived F4 and F5 generations of five wheat crosses: Kanchan × Gourab, Gourab × Fang 60, Kanchan × Pavon 76, Gourab × Pavon76 and Fang 60 × Pavon76. Each cross was consisted of 65, 60, 77, 72 and 64 F4 bulks including two parents. The study was conducted both in the field and laboratory of Wheat Research Centre, Dinajpur during 2002-03 and 2003-04. A completely randomized design for laboratory experiment and randomized complete block design for field experiments was followed with three replications. Acquired thermal tolerance through Membrane Thermo-stability assay was performed in controlled environment as per method described by Ibrahim and Quick (2001). Other morpho-physiological traits were measured from field experiment. The crosses Kanchan × Gourab, Kanchan × Pavon 76 and Fang 60 × Pavon76 showed high genetic variability with high population mean for MTS in F4 bulks. These crosses also exhibited high-observed response to selection, realized heritability and heritability in standard unit indicating expected good gain through early generation selection. Direct response to selection for this trait was significant in these crosses in F5 generation. Direct selection for MTS significantly improved biomass, grain yield, thousand grain weight, grain filling rate and canopy temperature depression in crosses Kanchan × Pavon 76, Gourab × Pavon76 and Fang 60 × Pavon76 with few exceptions. Direct selection of MTS also improved chlorophyll retention at 21 days after anthesis in crosses Gourab × Fang 60 and Gourab × Pavon76. Significant intergeneration correlations (F4 vs. F5) were observed for MTS in all five crosses studied indicating possibility of effective improvement of this trait through selection in early generation. Key words: Membrane thermostability; selection response; realized heritability; intergeneration correlation.DOI: http://dx.doi.org/10.3329/bjpbg.v23i2.9320 Bangladesh J. Pl. Breed. Genet., 23(2): 15-22, 2010

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Estimation of Genetic Parameters and Selection Response for Reproductive and Growth Traits in Rideau-Arcott sheep

Canadian Journal of Animal Science ◽

10.1139/cjas-2019-0152 ◽

2020 ◽

Author(s):

Mohammed Naser Boareki ◽

Luiz Brito ◽

Angela Cánovas ◽

V.R. Osborne ◽

Flavio S Schenkel

Keyword(s):

Litter Size ◽

Genetic Parameters ◽

Growth Traits ◽

Reproductive Traits ◽

Selection Response ◽

Direct Selection ◽

Correlated Response ◽

Response To Selection ◽

Weaning Weight ◽

Selection For

The goal of this study was to estimate genetic parameters and predict direct and correlated response to selection for lamb growth traits and ewe reproductive traits, based on single trait selection or combining multiple traits in an optimum index that targets total litter post-weaning weight in the first lambing as the main selection goal. Heritability estimates ranged from 0.04 to 0.19. Genetic correlations between growth and reproductive traits ranged from -0.24 to 0.15. The indirect response to selection for reproductive traits in later lambings, by selecting on first lambing performance, was 11 to 25% greater than direct selection. The response to indirect selection for composite reproductive traits, i.e. total weaning weight or total post-weaning weight, by selecting on individual lamb weaning weight or post-weaning weight was 1 to 69% greater than direct selection, but it was accompanied by a negative response on litter size. However, combining alternate growth and reproductive traits in optimum selection index resulted in correlated response of up to 96% greater than direct selection response for reproductive traits without a negative response on litter size. Therefore, multiple trait selection using an index of component traits was more effective than direct selection for a composite trait.

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RESPONSE TO SELECTION FOR STEM LENGTH IN RED CLOVER EVALUATED AT WIDE AND NARROW SPACINGS

Canadian Journal of Plant Science ◽

10.4141/cjps84-126 ◽

1984 ◽

Vol 64 (4) ◽

pp. 925-934 ◽

Cited By ~ 1

Author(s):

S. R. BOWLEY ◽

N. L. TAYLOR ◽

P. L. CORNELIUS ◽

C. T. DOUGHERTY

Keyword(s):

Recurrent Selection ◽

Trifolium Pratense ◽

Red Clover ◽

Stem Length ◽

Yield Response ◽

Response To Selection ◽

Breeding Programs ◽

Herbage Yield ◽

Trifolium Pratense L ◽

Selection For

Six cycles of phenotypic recurrent selection for stem length were conducted in a 91-cm-spaced planted population of red clover (Trifolium pratense L.) as a means of increasing herbage yield. The objectives of this investigation were (1) to compare the effectiveness of selection for stem length tested in transplants at wide (91 cm) and narrow (7 cm) spacings, and in row seedings and (2) to determine the effect of selection for stem length on herbage yield. Response to selection for stem length was obtained under all plantings; however, greater gains were observed at the wide transplant spacing (3.3 cm∙cycle−1) compared to the narrow transplant spacing (0.7 cm∙cycle−1) and row seeding (0.8 cm∙cycle−1). Densely spaced transplants gave performance similar to row seedings and may be of value to forage crop breeders in situations where yield or quality assessment is desired but seed supplies are insufficient for the establishment of seeded plots, such as in the early stages of breeding programs. Selection for stem length was effective in increasing herbage yield at first harvest but was associated with reduced persistance, decreased regrowth yields, and increased partitioning of dry matter towards the shoot rather than the root during seedling development. Selection for stem length in the regrowth or in the second year, rather than in the primary (seedling) growth, might have avoided the declines in persistence and regrowth yields.Key words: Trifolium pratense L., red clover, recurrent selection, stem length, density, herbage yield

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Effects of Incorporating Dry Matter Intake and Residual Feed Intake into a Selection Index for Dairy Cattle Using Deterministic Modeling

Animals ◽

10.3390/ani11041157 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1157

Author(s):

Kerry Houlahan ◽

Flavio S. Schenkel ◽

Dagnachew Hailemariam ◽

Jan Lassen ◽

Morten Kargo ◽

...

Keyword(s):

Feed Intake ◽

Feed Efficiency ◽

Selection Pressure ◽

Dry Matter ◽

Selection Index ◽

Residual Feed Intake ◽

Dry Matter Intake ◽

Direct Selection ◽

Response To Selection ◽

Selection For

The inclusion of feed efficiency in the breeding goal for dairy cattle has been discussed for many years. The effects of incorporating feed efficiency into a selection index were assessed by indirect selection (dry matter intake) and direct selection (residual feed intake) using deterministic modeling. Both traits were investigated in three ways: (1) restricting the trait genetic gain to zero, (2) applying negative selection pressure, and (3) applying positive selection pressure. Changes in response to selection from economic and genetic gain perspectives were used to evaluate the impact of including feed efficiency with direct or indirect selection in an index. Improving feed efficiency through direct selection on residual feed intake was the best scenario analyzed, with the highest overall economic response including favorable responses to selection for production and feed efficiency. Over time, the response to selection is cumulative, with the potential for animals to reduce consumption by 0.16 kg to 2.7 kg of dry matter per day while maintaining production. As the selection pressure increased on residual feed intake, the response to selection for production, health, and fertility traits and body condition score became increasingly less favorable. This work provides insight into the potential long-term effects of selecting for feed efficiency as residual feed intake.

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