Authors:G.C. Pandey, S. Sareen, P. Siwach, and R. Tiwari
Grain yield and quality under terminal heat stress (post anthesis) are the most complex traits that are influenced by environmental factors and are characterized by low heritability and large genotype × environment interactions. The present study was undertaken to determine effectiveness of selection for genotypes tolerant to heat stress using differences in 1000-grain weight (dTGW) under the optimum and late sown field condition. A Recombinant Inbred Line (RIL) mapping population derived from the heat sensitive genotype Raj 4014 and heat tolerant genotype WH730 was evaluated for the heat stress over 2 years in a replicated trial under optimum and late sown field conditions. The parental lines were screened with approximately 300 SSR (μsatellite) markers out of which about 20% showed polymorphism. These polymorphic markers were utilized for genotyping a subset that had clear contrasting variation for dTGW. The difference in TGW between the timely and late sown conditions was used as a phenotypic trait for association with markers. Analysis of the two years data under timely and late sown condition revealed parents and their RILs clearly showing variation with respect to the dTGW. Regression analysis revealed significant association of dTGW of RILs with two markers viz., Xpsp3094, and Xgwm282 with coefficients of determination (R2) values of 0.14 and 0.11, respectively.
Authors:D. Garg, S. Sareen, S. Dalal, R. Tiwari, and R. Singh
Terminal heat referred to as increase in temperature during grain filling, is one of the important stress factors for wheat production and is responsible for decline in wheat production in many environments worldwide. In order to meet the challenges of high temperature ahead of global warming, concerted efforts are needed to evaluate wheat genotypes for heat tolerance and develop genotypes suitable for such stressed environments. Twenty-seven advanced wheat genotypes developed for stress and normal environments by different research centres were evaluated during 2009–10 and 2010–11 under timely sown (normal) and late sown (heat stress) environments. Analysis of variance revealed that the genotypes differed significantly in grain filling duration (GFD), grain growth rate (GGR) and thousand-grain weight (TGW). Out of 27 genotypes, 16 were found to be tolerant for thousand-grain weight under late planting (heat stress) during 2009-10 but only 12 were tolerant during 2010–11. Many of the genotypes registered more reduction in thousand-grain weight during 2010–11 as compared to 2009–10; the temperatures during 2009–10 were higher. The differences in grain filling duration under two conditions during both seasons as well as difference in temperatures during first half of grain filling explain the reduction pattern in the genotypes. GFD had significant negative correlation with temperatures during post heading period and the difference in GFD under two environments had positive correlation with these temperatures. The reduction in GFD had regression of 33.3% on reduction in GGR and reduction in GGR had regression of 41.6% on reduction in TGW genotypes AKW 1071, DBW 17, HS 277, K 7903, K 9107, NW 1014 and RAJ 3765 had less sensitivity to stress environments during both years.
Authors:A. Adugna, A. Adugna, G. S. Nanda, G. S. Nanda, N. S. Bains, and N. S. Bains
-based) and chemically induced (CH9832- based) male sterility systems were compared for hybrid performance in wheat. A total of 40 genotypes including 10 CMS-based hybrids, 10 CHA-based hybrids, 10 B lines and 10 R lines were included in the experiment. analysis of variance revealed significant differences between the genotypes for all the characters studied. Differences between the hybrids and their parents were significant for all the characters. There were also significant differences between the hybrids resulting from the two systems of sterility. This study of 10 comparable hybrids showed, on average, midparent heterosis of 30.2 and 7.3% for CMS- and CHA-derived hybrids, respectively. Generally, the CMS-based hybrids were superior to their CHA-based equivalents for grain yield performance. In spite of the incomplete fertility the higher grain yield in CMS-based hybrids was attributed to the profuse tillering and high thousand-grain weight. On the other hand, the CHA-based hybrids had lower yield performance due to the lower thousand-grain weight and tillering. The lower grain weight and tillering in these hybrids compared with their CMS-based equivalents might be due to the toxic effect of the CHA, which was carried over to the hybrid and affected vigour. As a whole the CMS system was found to be better than the CHA system (based on the particular CHA used in this study) for hybrid performance in wheat.
Authors:A. Sreš, S. Trdan, G. Leskošek, M. Vidrih, and F. Vučajnk
The effect of spraying speed (5, 8.5 or 12 km/h) on deposition quality of fungicide on a winter wheat head, yield, grain quality, occurrence of Fusarium head blight (FHB) and deoxynivalenol (DON) content in grains was investigated in 2011 and 2012. Asymmetric double flat fan air-injector nozzles were used in the trial at a spraying pressure of 5.0 bars. A prothiconazole + tebuconazole fungicide mixture was used for spraying. An increase of spraying speed significantly lowered coverage values at the front and rear parts of a wheat head. At all three spraying speeds, the rear part of a wheat head reached a better coverage value. The effect of spraying speed was significant in 2011, when the 5 km/h spraying speed generated a significantly higher grain yield and a significantly higher thousand-grain weight in comparison with the other treatments. In both trial years, the lowest grain yield occurred on the unsprayed control. In 2011 and 2012, the latter also reached the lowest hectolitre weight and thousand-grain weight. In both trial years, the unsprayed control had a significantly higher DONcontent than the other treatments. In 2012, the DONcontent on the unsprayed control exceeded the allowed maximum level. The spraying speed did not affect the DON content in the grains. The effect of spraying speed was also noted in the FHB incidence. A significantly lower FHB incidence occurred at the 5 and 8.5 km/h spraying speeds.
Authors:L. Hanifi-Mekliche, A. Mekliche, and P. Monneveux
The objectives of this research were to assess the genotype × environment interaction and to identify barley (Hordeum vulgare L.) genotypes with high stability for grain yield, yield components, straw height, ear length, heading time, straw yield and harvest index. Eighteen barley breeding lines and one commercial cultivar were evaluated under field conditions during five growing seasons. The trials were carried out under both rainfed and irrigated conditions during the first four years and under rainfed conditions only during the last growing season. Stability studies showed significant differences between the environments for all the traits and between the genotypes for thousand-grain weight, heading time and ear length. The genotype × environment interaction was, however, not significant according to the Finlay-Wilkinson analysis. The analysis of correlations between the various traits showed the importance of selecting for earliness, high number of grains/ear, stem height and ear length in order to obtain acceptable grain yields under drought-stressed conditions.
Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. The aim of this study was to investigate the effect of short periods of high temperature, drought and their combination at different growth stages of plant under controlled conditions. The effects of high temperature and drought on grain yield were additive. However, high temperature increased the degree of water stress and the combined effects of drought and high temperature were much more severe than those of each individual treatment. High temperature and drought applied at post- anthesis shortened duration of maturation, grain filling duration and reduced grain yield, mean grain weight, grain number and thousand-grain weight.
Authors:M. Oak, S. Tamhankar, V. Rao, and S. Misra
Ten dicoccum wheats were analyzed for their physico-biochemical and milling properties to evaluate the pasta making potential. Dicoccums showed higher protein content and mixograph midline peak values compared to durum variety MACS2846. Mixographic properties of dicoccums were poor compared to durums, due to lower functional visco elastic gluten content. Dicoccums were poorer in milling properties compared to durums, due to lower test weight and thousand-grain weight. Among dicoccums, DDK 1025 showed high micro SDS sedimentation volume and strong mixographic properties, but values were still lesser compared to durum MACS 2846. HMW glutenin subunits in recently developed/released dicoccums were similar to durum parents and were different from the older dicoccums. LMW glutenin subunits, however, were similar to dicoccum parents, except in DDK 1025 which showed LMW glutenin subunits similar to durum wheat. To breed high quality dicoccum wheat for pasta products, breeders should select superior glutenin subunits composition, along with better mixograph properties, keeping morpho-botanical characteristics of dicoccum wheat.
Wheat production is limited primarily by water deficiency. The challenge of our days is to increase production with less water by promoting biological basis of drought tolerance and higher water use efficiency (WUE).Eight genotypes were examined to make comparison of their response to drought. The plants were grown in pots filled with 8.5 kg soil. The drought stress was started at the mid-flowering stage (Zadoks’ scale: 65) and continued till maturity by adding only 50% of the water given to the control pots. Morphological and physiological characteristics known to be related to drought tolerance were examined.Duration of grain filling was shortened by 3 days in the mean of genotypes, the number of productive tillers were reduced by about 20% in case of the newly bred cultivars and 4–11% for extensive genotypes because of water deficiency. The highest root dry weight increment was measured in case of Emese (71%) and Pántlika (54%), while Cap.Des. increased it’s root weight only by 24%. Yield reduction was found between 11- and 44% and was mainly due to decrease of thousand grain weight (TGW). Regarding netto photosynthetic activity, intensive cultivars had positive balance even in stress treatment, while the extensive genotypes reacted with quick closing of stomata. The genotypes with small yield decrease proved to improve their WUE to a grater extent. According to our results Pántlika and Emese proved to be drought tolerant cultivars.
A field experiment was conducted to investigate the effect of soil application of zinc fertilizer on yield and yield components of wheat (
L. cv. Inqlab 91) grown on calcareous soil in Pakistan. The levels of zinc sulphate were 0 (control), 5, 10, 15, 20, 25 and 30 kg ha
and the zinc sulphate was combine-drilled at the time of sowing. Zinc sulphate increased the Leaf Area Index, the total number of fertile tillers m
, number of spikelets spike
, spike length, grain spike
, thousand grain weight, grain yield, straw yield and biological yield and decreased harvest index. Most of the response trends were curvilinear although the decrease in harvest index was linear. All applications of zinc sulphate gave economic increases in margins over costs but the application of 5 kg ha
gave the highest marginal rate of return. It is recommended that under such calcareous soil conditions growers can expect good returns from the application of 5 kg zinc sulphate ha
at the time of sowing but if the grain price were to increase or the price of zinc sulphate were reduced economic responses could be expected from higher levels of zinc sulphate.
Wangshuibai is an indigenous scab resistance germplasm originated from Jiangsu, China. To characterize the genetic basis of scab resistance in this germplasm, QTLs for type I and type II resistances were detected using a recombinant inbred line (RIL) population created by single seed descent from Nanda2419 × Wangshuibai and a molecular marker map of more than 4000 cM constructed using RAPD, SSR and STS markers. The major QTLs for type I resistance in Wangshuibai were mapped to chromosomes 4BL and 5AS, and those for type II resistance were mapped to chromosomes 3BS. In addition, a QTL on chromosome 2B showed association with both types of resistance. These QTLs were verified with QTL nearisogenic lines. We found, by mapping QTLs for agronomical traits in the same population, that on chromosomes 4BL and 5AS the scab resistance QTLs co-located with QTLs for plant height, thousand grain weight or flag leaf width. However, these associations could be break down by recombinant selection. We concluded that Wangshuibai is a valuable scab resistance gene resources and marker assisted selection would be of great help for its better utilization.