Resilience in Spring Wheat Genotypes: Physiological and Agronomic Changes Under Terminal Water Stress Conditions

Cantonese noodles are a possible end‐use product for spring wheat (Triticum aestivum L.). This product may provide an export opportunity for growers and be an alternative to the pan bread market. It might also be possible to produce dual‐use spring wheat for both markets. Knowledge of genotype and environment effects on spring wheat quality characteristics relating to Cantonese noodle discoloration will assist breeders in developing cultivars. Nine spring wheat genotypes were grown at four North Dakota locations in 2000 and 2001. Samples were analyzed for kernel polyphenol oxidase (PPO) activity, flour protein content, kernel brightness, and flour ash content. Yellow alkaline Cantonese‐style noodle sheets were made from flour milled from each sample and brightness (L*) and yellowness (b*) color measurements taken at 0 and 24 h to evaluate noodle discoloration. Genotypes having low kernel PPO activity, moderate flour protein content, bright kernels, and low flour ash concentrations produced Cantonese noodle sheets having high brightness and yellowness after 24 h. Genotype by environment interactions were significant for wheat quality characteristics related to noodle quality, due in part to rank changes in genotype means across environments. Genotype IDO 470 was identified as having desirable wheat quality characteristics for Cantonese noodle color, indicating that spring wheat genotypes with acceptable noodle quality can be produced for the region. The development of dual‐use spring wheat genotypes may be possible if breeders select for traits that maximize noodle quality but are neutral or have no significant impact on pan bread quality.

Mechanisms of drought tolerance based on root architecture and lipid composition in wheat are poorly understood. We quantified the differences in root morphological traits and phospholipids and galactolipids levels between winter and spring wheat genotypes at variable water supply amounts (drought stress). Experiments were conducted using seven winter and four spring wheat (Triticum aestivum) genotypes. In the first experiment, solid agar medium was used to quantify seminal root angles. In the second experiment, the plants were grown in 150-cm columns in a greenhouse under full and deficit water supply for 65 days to record root architecture. The root tips (2-cm-long) were used for quantifying polar lipids. Drought stress at vegetative stage decreased plant height (14%), total dry matter production (48%), maximum root length (25%), root length:shoot length ratio (11%), and other root traits. Winter wheat genotypes had ~1.5 times higher maximum root length than spring wheat genotypes. Significant differences in molar percentages of root phospholipids and galactolipids, molecular species, and double bond index of galactolipids were observed among spring wheat but not winter wheat genotypes. Based on the genotypes studied, the drought tolerant mechanism of winter wheat was associated with deep root system, and in spring wheat it was well branched (albeit shallow) root system with more unsaturated membrane lipids.

Using stress tolerance indicator (STI) to select high grain yield iron-deficiency tolerant wheat genotypes in calcareous soils

The immature embryos during seed development were examined to predict the suitable embryos for an efficient regeneration system. Five spring wheat genotypes and five winter wheat genotypes were tested using immature embryos as explants. Spring wheat genotypes showed much higher levels of plant regeneration than those of winter wheat genotypes. The highest frequencies of embryogenesis and regeneration were obtained when embryos at 13-14 days after anthesis (DAA) were used as explant and decreased using embryos at 21-22 DAA during seed development. Significant differences were also found for callus induction and regeneration as affected by immature embryo size. The regeneration efficiency was drastically decreased in spring and winter wheat genotypes when embryos larger than 2.0 mm of length were used. The optimum developmental stage and embryo length for regeneration efficiency were at 13-14 DAA and 1.0-1.5 mm, respectively. The selection of suitable embryos for the high frequencies of embryogenesis and regeneration leads us to efficient genetic improvement of wheat.

The success of winter × spring wheat hybridization programmes depends upon the ability of the genotypes of these two physiologically distinct ecotypes to combine well with each other. Hence the present investigation was undertaken to study the combining ability and nature of gene action for various morpho-physiological and yield-contributing traits in crosses involving winter and spring wheat genotypes. Five elite and diverse genotypes each of winter and spring wheat ecotypes and their F 1 (spring × spring, winter × winter and winter × spring) hybrids, generated in a diallel mating design excluding reciprocals, were evaluated in a random block design with three replications. Considerable variability was observed among the spring and winter wheat genotypes for all the traits under study. Furthermore, these traits were highly influenced by the winter and spring wheat genetic backgrounds, resulting in significant differences between the spring × spring, winter × winter and winter × spring wheat hybrids for some of the traits. The winter × spring wheat hybrids were observed to be the best with respect to yieldcontributing traits. On the basis of GCA effects, the spring wheat parents HPW 42, HPW 89, HW 3024, PW 552 and UP 2418 and the winter wheat parents Saptdhara, VWFW 452, W 10 and WW 24 were found to be good combiners for the majority of traits. These spring and winter wheat parents could be effectively utilized in future hybridization programmes for wheat improvement. Superior hybrid combinations for one or more traits were identified, all of which involved at least one good general combiner for one or more traits in their parentage, and can thus be exploited in successive generations to develop potential recombinants through various breeding strategies. Genetic studies revealed the preponderance of additive gene action for days to flowering, days to maturity and harvest index, and non-additive gene action for the remaining six traits.

Among all abiotic stresses, drought is undoubtedly the major factor, which, individually or combined with heat stress, limits crop productivity worldwide. Considering these facts, four spring barley and two spring wheat genotypes were evaluated under two stress (early and late) conditions in a southern arid region of Russia in order to identify suitable spring wheat and barley genotypes for that region and to assess the optimum sowing time for specific genotypes. High temperature followed by deficit soil moisture affected all stages from germination through to reproduction of crop when sown late, finally drastically reducing yield. On the other hand, due to low temperature, germination and stand establishment of crop sown early were highly affected, resulting in lower grain yield. Thus, high temperature (air and soil) followed by drought (deficit soil moisture) in the late-sown crop (from germination to reproductive stages) and low temperature in germination through vegetative stages of the early-sown crop are the most important constraints for crop production in this arid region. From the overall performance (yield, relative performance and stress susceptibility index), genotype ‘Zernograd.770’ is recommended for both early and late drought stressed areas and ‘Ratnik’ were sensitive to stress both at low temperatures when sown early and high temperatures followed by drought when sown late. Key words: High temperature, drought, spring wheat, barley, Russia.

Yield and developmental characteristics of crop genotypes grown at different levels of water availability are often used to select genotypes that are adapted to variable moisture environments. Field studies were conducted at Aberdeen. Idaho, USA in 1992 and 1993 to evaluate the effects of varying moisture supply on grain yield and yield components of spring wheat genotypes. In both years, 12 spring wheat (Triticum aestivum L.) genotypes were grown under three irrigation levels (well-watered. moderate water-stress and severe water-stress) imposed during the periods from mid-tillering to anthesis with a line source sprinkler irrigation system. Grain yield and yield components (spikes m-2, spikelets spike-1, kernels spikelet-1, kernels spike-1, and kernel weight) were used to evaluate the genotypic response to water stress. Overall, water stress caused a reduction in grain yield and yield components. Genotypes exhibited a large year-to-year variation in their ranks for grain yield. Medium-tall growing genotypes (IDO 367. lDO 369 and Rick) generally produced high yields under water stress conditions in 1992 (relatively dry year), while short -medium genotypes (WPB 926. Yecora Rojo and Pondera) produced high yields under water stress conditions in 1993 (relatively wet year). Chris and Serra were the lowest yielding genotypes under water stress conditions in both years. Under moderate stress conditions. 100 367 and Yecora Rojo had consistently high yields. Genotypic yield differences under water stress conditions were primarily related to the differences in the numbers of spikes m". Therefore, a tendency for high plasticity for Spikes per unit area could be used to select wheat genotypes for improved drought tolerance.

Superior bread‐making quality is a primary objective for most hard red wheat (Triticum aestivum L.) breeding programs. Milled white flour is traditionally used to measure quality. There is increasing demand in the domestic market for whole grain bread products. The objective of this research was to determine the relationship of bread quality parameters based on white flour versus whole wheat flour in a set of hard red spring and hard red winter wheat genotypes. Quality evaluations were conducted on sets of genotypes grown in four environments for both wheat classes. Correlations of genotype performance for white flour versus whole meal varied with the traits. Protein levels were highly correlated, but correlations tended to decrease as dough was processed into a final product. This was especially true for hard red spring wheat genotypes. Mixograph tolerance of white flour versus whole meal was correlated highly for both spring and winter wheat, while water absorption was correlated poorly for both classes of wheat. Correlations for final loaf volume of whole wheat versus white flour was significant in two environments, and ranged from 0.08 to 0.72 for spring wheat genotypes. Correlations for loaf volume were significant in all environments, and ranged from 0.76 to 0.92 for winter wheat genotypes. In general, our data indicated that quality measured on white flour could be used as an estimate of whole wheat performance, but that identification of the best genotypes for whole wheat performance may require separate quality analysis.

Rhizoctonia root rot, caused by Rhizoctonia solani Kühn AG-8 (Anastomosis Group 8), is a yield limiting disease of direct-seeded cereal grains. The objectives of this study were to (i) determine whether spring wheat (Triticum aestivum L.) genotypes vary in susceptibility to Rhizoctonia root rot in inoculated field trials; and (ii) evaluate whether disease ratings obtained by controlled environment (CE) analyses are predictive of disease ratings or genotype performance in the field. Twenty-one spring wheat genotypes were evaluated for two crop years in a split-plot field study with high and low levels of disease pressure. The high-inoculum (high) treatment consisted of plots planted the previous fall with a 3:1 mixture of winter wheat and oat (Avena sativa L.) grains colonized by the pathogen. The low-inoculum (low) treatment was neither inoculated nor planted with a green bridge host the previous fall. Genotypes also were assayed for disease reaction in controlled environment (CE) assays. Average disease ratings of field entries in the high treatment were 2.1 times greater than those from the low treatment (P < 0.05). The yield average of entries in the high treatment was 87% of that of entries in the low treatment (P < 0.001). Adult plant heights also were 5 cm shorter (P < 0.001), heading date was slightly delayed (P < 0.05), and grain protein content decreased slightly (P < 0.05) in the high compared with the low treatment. Test weight was not affected by inoculum level. A statistically significant, negative association (P < 0.0001) between disease rating and grain yield was detected, and variation for reaction to R. solani was detected among genotypes. Disease reaction differences were not detected among genotypes in CE assays, and field and CE disease ratings were not correlated (P = 0.32), indicating that growth chamber assays were not prognostic of genotype performance in response to pressure from Rhizoctonia root rot in the field.

Rhizoctonia root rot, caused by Rhizoctonia solani Kühn AG‐8 (Anastomosis Group 8), is a yield limiting disease of direct‐seeded cereal grains. The objectives of this study were to (i) determine whether spring wheat (Triticum aestivum L.) genotypes vary in susceptibility to Rhizoctonia root rot in inoculated field trials; and (ii) evaluate whether disease ratings obtained by controlled environment (CE) analyses are predictive of disease ratings or genotype performance in the field. Twenty‐one spring wheat genotypes were evaluated for two crop years in a split‐plot field study with high and low levels of disease pressure. The high‐inoculum (high) treatment consisted of plots planted the previous fall with a 3:1 mixture of winter wheat and oat (Avena sativa L.) grains colonized by the pathogen. The low‐inoculum (low) treatment was neither inoculated nor planted with a green bridge host the previous fall. Genotypes also were assayed for disease reaction in controlled environment (CE) assays. Average disease ratings of field entries in the high treatment were 2.1 times greater than those from the low treatment (P &lt; 0.05). The yield average of entries in the high treatment was 87% of that of entries in the low treatment (P &lt; 0.001). Adult plant heights also were 5 cm shorter (P &lt; 0.001), heading date was slightly delayed (P &lt; 0.05), and grain protein content decreased slightly (P &lt; 0.05) in the high compared with the low treatment. Test weight was not affected by inoculum level. A statistically significant, negative association (P &lt; 0.0001) between disease rating and grain yield was detected, and variation for reaction to R. solani was detected among genotypes. Disease reaction differences were not detected among genotypes in CE assays, and field and CE disease ratings were not correlated (P = 0.32), indicating that growth chamber assays were not prognostic of genotype performance in response to pressure from Rhizoctonia root rot in the field.

Evaluation of heat stress tolerance in spring wheat (Triticum aestivum L.) genotypes using stress tolerance indices in western region of Nepal

Synergistic role between phosphorus and water use efficiency in spring wheat genotypes

Drought is a significant abiotic stress that negatively impacts plant growth and can lead to substantial crop yield losses. Our study aimed to establish selection criteria for 200 spring-wheat (Triticum aestivum L.) genotypes exposed to three different field-capacity (FC) levels (100%FC, 50%FC, 25%FC) in a growth chamber (seedling traits) and in the field under withholdirrigation conditions (yield traits). Variance, correlation, and principal component analysis (PCA) was performed to identify genotypes with high tolerance to drought stress. The stress induction significantly affects morphophysiological traits i.e., root length, root weight (fresh, dry), fresh shoot weight, relative water contents and root shoot ratio in spring wheat genotypes at seedling stage. The traits flag leaf area, spike weight, grain weight/spike, biological and grain yield were interlinked and strongly influenced by drought in the field. The mean grain yield performance decreased from 21.85 g to 19.46 g under variable water regimes; however, the differences in harvest index and spikelets/spike were not significant. Among the tested genotypes, 9970 and 36-Eswyt-42 showed better root architecture development, leaf water management system, biological yield (66.07 g, 56.23 g) and grain yield (27.47 g, 28.78 g), respectively. The traits we identified may serve as an indirect selection index to enhance current semi-arid wheat germplasm and develop high-yielding drought-tolerant lines in advanced generations. Keywords: Mini core collection, Seedling and yield traits, Selection criteria, Variability analysis

A pot experiment was conducted during kharif season 2022 with two rice genotypes IR 64 (drought sensitive) and Nagina 22 (drought tolerant) to evaluate physio-biochemical changes under terminal water stress condition in department of Molecular biology and Biotechnology, Acharya Narendra deva University of agriculture and Technology, Kumarganj, Ayodhya 224229, Uttar Pradesh, India. The water treatment of 14 days was given at initiation of flowering under pot culture treatments. Leaf rolling pattern, Relative water Content (RWC), Chlorophyll content, Proline content, catalase and Peroxidase activity were recorded at the end of water stress against control condition. The Nagina 22 had less leaf rolling, high RWC, high proline content, catalase and peroxidase activity under water stress condition and showed less reduction in days to 50% flowering, effective tillers number, grains panicle-1, test weight and grain yield plant-1 under water stress condition comparatively IR 64 rice genotype. The Transient leaf rolling, high RWC, stay green, accumulation of high proline content, high catalase activity at terminal stage water stress responsible for less reduction yield and yield contributing traits can be taken as physio-biochemical indices for screening water stress tolerant in rice genotypes.

Fusarium head blight (FHB), caused by several Fusarium spp., is a worldwide problem that severely impacts cereal grain yield and poses major risks to human and animal health due to production of the mycotoxin deoxynivalenol (DON) and its acetylated forms, 3-acetyl-DON (3-ADON) and 15-acetyl-DON (15-ADON). Recent studies suggest an inconsistent effect of F. graminearum chemotypes and resistance of wheat (Triticum aestivum) genotypes. To gain insight into the interaction effects of F. graminearum chemotypes and spring wheat genotypes on FHB resistance response, 10 spring wheat genotypes with varying levels of FHB resistance were inoculated with 10 F. graminearum isolates, consisting of 5 3-ADON- and 5 15-ADON-producing isolates and evaluated in type I (spray inoculation) and type II (point inoculation) resistance assays. Wheat genotypes carrying the resistance allele of the Fhb1 quantitative trait locus on chromosome 3BS had lower disease in type II evaluations, regardless of F. graminearum isolate or chemotype. Isolates of F. graminearum were also significantly different for disease aggressiveness. In addition, the 3-ADON-producing isolates were 18% more aggressive than the 15-ADON isolates in type I resistance assays. No difference in aggressiveness of the two chemotypes was observed, when tested in type II resistance assays. There was no interaction effect between F. graminearum chemotypes and spring wheat genotypes, suggesting that screening of germplasm for resistance can be performed with limited number of aggressive isolates.