Posts Tagged ‘Canopy temperature’

Physio-agronomic traits evaluation of wheat genotypes for Adaptability under rainfed conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Sarhad Journal AGriculture 30 (2151-156, 2014.

Sohail, M.;Hussain, I.; Din, R.; Tanveer, S.K.; Qamar, M.; Abbas, S.H.

High temperature stress during grain filling stages is one of the main wheat yield limiting factors under rainfed conditions of Pakistan. A field experiment was carried out to evaluate physio-agronomic traits of different wheat genotypes for better yield and heat tolerance under rainfed conditions. Variable growing conditions during grain filling period were created by sowing crop on normal (November 15) and late sowing dates (December 15). Crop planted on normal sowing date had significant affect (p<0.05) and produced 29% higher grain yield as compared to late planting. Significant variation (p<0.05) was also noticed among genotypes in terms of physiological and agronomic traits under both under both normal and late sowing dates, as advance line NR-397 and NARC-09 produced significantly higher (p<0.05) grain yields as compared to NR-400 and NR-379. Higher grain yields of these two cultivars were associated with their more number of days to maturity, higher spikes m2 and heavier grains as compared to other two genotypes. At the same time, grain yields of wheat genotypes showed a strong correlation to their leaf chlorophyll (+0.98) and canopy temperature (-0.99) measurements. Higher grain yields of NR-397 and NARC-09 were directly correlated to the

QTL for yield, yield components and canopy temperature depression in wheat under late sown field conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2013

R. Esten Mason, Dirk B. Hays, Suchismita Mondal, Amir M. H. Ibrahim and Bhoja R. Basnet

A wheat (Triticum aestivum L.) recombinant inbred line (RIL) population was used to identify quantitative trait loci (QTL) associated with yield, yield components, and canopy temperaturedepression (CTD) under field conditions. The RIL population, consisting of 118 lines derived from a cross between the stress tolerant cultivar ‘Halberd’ and heat stress sensitive cultivar ‘Karl92’, was grown under optimal and late sown conditions to impose heat stress. Yield and yield components including biomass, spikes m−2, thousand kernel weight, kernel weight and kernel number per spike, as well as single kernel characteristics were determined. In addition, CTD was measured during both moderate (32–33 °C) and extreme heat stress (36–37 °C) during grain-filling. Yield traits showed moderate to high heritability across environments with a large percentage of the variance explained by genetic effects. Composite interval mapping detected 25 stable QTL for the 15 traits measured, with the amount of phenotypic variation explained by individual QTL ranging from 3.5 to 27.1 %. Two QTL for both yield and CTD were co-localized on chromosomes 3BL and 5DL and were independent of phenological QTL. At both loci, the allele from Halberd was associated with both higher yield and a cooler crop canopy. The QTL on 3BL was also pleiotropic for biomass, spikes m−2, and heat susceptibility index. This region as well as other QTL identified in this study may serve as potential targets for fine mapping and marker assisted selection for improving yield potential and stress adaptation of wheat.

Infrared thermal imaging as a rapid tool for identifying water-stress tolerant maize genotypes of different phenology

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Agronomy and Crop Science, 2013

S. Zia, G. Romano, W. Spreer, C. Sanchez, J. Cairns, J.L. Araus and J. Muller

The main task of this research was to evaluate canopy temperature and Crop Water Stress Index (CWSI) by assessing genotype variability of maize performance for different water regimes. To that end, three hundred tropical and subtropical maize hybrids with different phenology in terms of date of anthesis were evaluated. The influence of phenology on the change in canopy temperatures and CWSI was not equal during the three dates of measurement. At the end of vegetative growth (82 days after sowing, DAS) and at the blister stage (DAS 97), a high significant difference in temperatures and CWSI (P < 0.001) were obtained between the early- and late-maturity genotypes. During anthesis (DAS 89), phenology had a significant effect (P < 0.01) only for the well-watered genotypes, while under water-stress conditions, no differences were found between early and late genotypes in terms of canopy temperature and CWSI. High significant differences (P < 0.001) in stomatal conductance (gs) between early and late genotypes for different treatments were observed. A relationship (R2 = 0.62) between gs and canopy temperature was obtained. Under a water-stress canopy, temperature was measured at anthesis, which was negatively correlated with grain yield of the early (r = −0.55)- and late (r = −0.46)-maturity genotypes in the water-stressed condition.

Use of thermography for high throughput phenotyping of tropical maize adaptation in water stress

Posted by on , in Journal Articles

Published in Computers and Electronics in Agriculture 79(1): 67-74, 2011

Use of thermography for high throughput phenotyping of tropical maize adaptation in water stress

Giuseppe Romano, Shamaila Zia, Wolfram Spreer, Ciro Sanchez, Jill Cairns, Jose Luis Araus and Joachim Müller

In this study the suitability of thermal imaging for phenotyping was investigated as part of a breeding experiment carried out by the International Maize and Wheat Improvement Centre (CIMMYT) at Tlaltizapán experimental station in Mexico. Different subtropical maize genotypes with two replications were screened with respect to their tolerance to water stress. Thermal images of the canopy of 92 different maize genotypes were acquired on two different days in the time interval between anthesis and blister stages (grain filling 1), whereby each picture contained five plots of different genotypes and canopy temperatures calculated for each plot. Significantly, lower canopy temperatures were found in well-watered genotypes compared with water-stressed genotypes. Furthermore significant differences (p < 0.001) between genotypes under water stress were detected using thermal images. A close correlation (p < 0.01–0.001) between canopy temperature or modified Crop water stress index with NDVI and SPAD values was obtained. It may be concluded that genotypes better adapted to drought conditions exhibited lower temperatures.

Thermography is a potentially promising method to accelerate the screening process and thereby enhance phenotyping for drought adaptation in maize.

Phenotyping approaches for physiological breeding and gene discovery in wheat

Posted by on , in Journal Articles

Published in Annals of Applied Biology 155: 309-320

Phenotyping approaches for physiological breeding and gene discovery in wheat

Reynolds, M.; Manes, Y.; Izanloo, A.; Langridge, P.

Conceptual models of drought-adaptive traits have been used in breeding to accumulate complementary physiological traits (PT) in selected progeny, resulting in distribution of advanced lines to rain-fed environments worldwide by the International Maize and Wheat Improvement Center (CIMMYT). Key steps in PT breeding at CIMMYT include characterisation of crossing block lines for stress adaptive mechanisms, strategic crossing among parents that encompass as many target traits as possible and early generation selection (EGS) of bulks for canopy temperature (CT). The approach has been successful using both elite × elite crosses as well as three way crosses involving stress adapted landraces. Other EGS techniques that are amenable to high throughput include measurement of spectral reflectance indices and stomatal aperture-related traits. Their genetic- and cost-effectiveness are supported by realisation of genetic yield gains in response to trait selection, and by economic analysis, respectively. Continual reselection within restricted gene pools is likely to lead to diminishing returns, however, exotic parents can be used to introduce new allelic diversity. Examples include landraces from the primary gene pool, and products of inter-specific hybridisation with the secondary gene pool consisting of closely related wheat genomes. Both approaches have been successful in introducing stress-adaptive traits. The main problem with knowing which genetic resource to use in wide-crossing is the uncertainty with which phenotypic expression can be extrapolated from one genome/genepool to another because of their unimproved or undomesticated genetic backgrounds. Nonetheless, their PT expression can be measured and used as a basis for investing in crossing or wide crossing. Discovering the genetic basis of PT is highly complex because putative QTLs may interact with environment and genetic background, including genes of major effect. Detection of QTLs was improved in mapping populations where flowering time was controlled, while new mapping populations have been designed by screening potential parents that do not contrast in the Rht, Ppd and Vrn alleles. Association genetics mapping is another approach that can be employed for gene discovery using exclusively agronomically improved material, thereby minimising the probability of identifying yield QTLs whose alleles have been already improved by conventional breeding.