Tested Wheat Cultivars Research Articles

Assessing genetic resistance to spot blotch, Stagonospora nodorum blotch and tan spot in wheat from Nepal

Fungal leaf spot diseases of wheat (Triticum aestivum L.) in Nepal cause significant yield reduction. Although field testing has identified a few partially resistant cultivars, most wheat grown in Nepal lacks adequate resistance to leaf spot diseases. During 2009–2010, 116 local and commercial spring wheat cultivars and advanced breeding lines were selected from multi-year field experiments in Nepal and evaluated for seedling resistance to three leaf spot diseases: spot blotch, Stagonospora nodorum blotch (SNB) and tan spot races 1 and 5 (two of the most prevalent races) in the growth chambers at North Dakota State University, Fargo, ND, USA. The wheat cultivars and lines were artificially inoculated with individual pathogens or races at the two-leaf stage and disease reactions were evaluated 6 to 10 days after inoculation (DAI). Results indicated that 30%, 31%, 19% and 10% of the tested wheat cultivars and lines were resistant to spot blotch, SNB, tan spot races 1 and 5, respectively. Six advanced breeding lines (SW89-5422, BL 2127 = DANIAL88/HLB30//NL297, BL 3033, FILIN/IRENA/5/CNDO/R143//ENTE/MEXI-2/3/AE. SQUA (TAUS)/4WEAVER, GAN/AE.SQUARROSA (236)//DOY1/AE.SQUARROSA(447)/3/MAIZ/4/INQALAB91, Mayoor//TK SN1081/Ae. Squarrosa (222)/3/FCT, were resistant to spot blotch, SNB and tan spot race 1. Similarly, two wheat cultivars Chirya 3 and Chirya 7 were resistant to spot blotch, and tan spot races 1 and 5. The resistant wheat lines identified in this study represent potentially useful and untapped sources of resistance to multiple leaf spot diseases and should be utilized in wheat breeding programs in Nepal in order to develop wheat cultivars with broad-spectrum resistance.

Allelopathy regulates wheat genotypes performance at the enhancement stage by soil water and prohydrojasmon (PDJ)

Growth adaptation and allelopathic potential of four winter wheat (Triticum aestivum L.) accessions has been investigated in pot experiments by prohydrojasmon (PDJ, 10 - 5M) and soil water (75 and 45%) at the enhancement stage. This paper also presented the performance of photosynthesis, water use and weed suppression. The effect of soil water and PDJ on wheat performance displayed significant differences depending on tested wheat cultivars and measured parameters. Water deficit decreased plant biomass significantly and changed phenotypic characteristics like plant height and leaf area of wheat. However, PDJ was found to stimulate wheat root growth and development so as to enhance pressure resistance and induce strong allelopathic potential and weed resistance. Physiological response in var. Lankao 95 - 25 to water shortage and PDJ was significantly relative to net photosynthesis rate and water use efficiency. Water deficit and PDJ would lead to plant phenotype and photosynthesis change and consequently, influence allelopathic expression and weed suppression of wheat based on Canonical Correspondence Analysis (CCA). Water deficit would induce the production and accumulation of more allelochemicals in wheat by passive transport of energy cost. Differing the regulation mechanism of water stress, PDJ showed active transport of energy supply in allelopathic stimulation, which implied that PDJ mainly exhibited its hormone effect to regulate and control wheat growth and development such as improving phenotypic features on competition at the basis of increasing growth cost. Therefore, it was possible for artificial measures to regulate allelopathic potential and weed resistance capacity of winter wheat cultivars, especially, in the arid areas of Loess Plateau of China.

Intraspecific variation in sensitivity to ultraviolet-B radiation in endogenous hormones and photosynthetic characteristics of 10 wheat cultivars grown under field conditions

Field studies were conducted to determine the potential of altering endogenous hormones and photosynthetic characteristics and intraspecific variation in sensitivity of 10 wheat ( Triticum aestivum) cultivars (four tolerant, two middle sensitive and four sensitive) to enhanced ultraviolet-B (UV-B, 280–315 nm) radiation under field conditions. The supplemental UV-B radiation was 5.00 kJ m − 2, simulating a depletion of 20% stratospheric ozone. Responses were cultivar-specific. Out of the 10 tested wheat cultivars, six showed significant decrease in IAA content. UV-B radiation significantly increased ZR content in two wheat cultivars and significantly decreased in five cultivars. ABA content of three wheat cultivars was increased significantly, while that of five cultivars was decreased significantly. UV-B radiation significantly increased the stomatal conductance of three cultivars, and significantly decreased that of four cultivars. Intercellular CO 2 concentrations were significantly increased in five cultivars and significantly decreased in one cultivar (Mianyang 20). Transpiration rate of three cultivars significantly increased, while that of three cultivars significantly decreased. UV-B radiation significantly decreased the net photosynthetic rate of six cultivars. Intraspecific differences were found for the different measured parameters. For seven measured parameters, UV-B radiation had significant effects on five wheat cultivars, while no effect on the others. Significant correlations were observed between net photosynthetic rate and stomatal conductance, intercellular CO 2 concentrations and transpiration rate in eight cultivars. UV-B radiation might change stomatal conductance, intercellular CO 2 concentrations and transpiration rate, thus resulting in changes in net photosynthetic rate.

Sensitivity of Winter Wheat Cultivars to Selected Herbicides

Sensitivity of Winter Wheat Cultivars to Selected HerbicidesThe experiments on tolerance of winter wheat cultivars to herbicides were performed under field conditions during 2003-2005 in the region of Wrocław (South-West of Poland). Five cultivars were examined (Zyta, Tonacja, Sukces, Clever, Kobra). Two herbicide mixtures: isoproturon + pendimethalin and diflufenican + flurtamon were applied in the autumn, in stage of 3-4 leaves. In the spring, when wheat reached stage of full tillering, the following herbicides were used: florasulam + 2.4-D and fluroxypyr + 2.4-D. Phytotoxicity of herbicides was determined on the base of plants vigour assessment, plants counting, yield and some yield components. During the experimental period, impact of the mixture pendimethalin + isoproturon on grain yield of Clever cultivar was observed only in the season with hard winter conditions (2002/2003). The remaining varieties: Zyta, Tonacja, Sukces and Kobra were completely tolerant to this herbicide mixture. Mild winter seasons did not show a negative influence of herbicides on grain yield of tested varieties. All cultivars showed a complete tolerance to diflufenican + flurfamon and florasulam + 2.4-D. The mixture fluroxypyr + 2.4-D caused ear deformation of all tested wheat cultivars, but did not affect negatively grain yield.

Correlation between cell wall-degrading enzymes in wheat leaves infected by Septoria tritici and disease severity

Investigation of enzyme activity in extracts from wheat leaves inoculated with Septoria tritici revealed activity of the following enzymes: xylanase, cellulase, protease, and α-amylase. Levels of xylanase, protease, and cellulase activities were closely correlated (P > 0.05) to fungal antigens as measured by ELISA and visual disease data on infected leaves from greenhouse experiments and field trials in 2002 and 2003. For the tested wheat cultivars, levels of these three enzymes also showed a good correlation (R = 0.65–0.97) with susceptibility ratings from the Bundessortenamt (Federal Office of Plant Variety) recommended cultivar list, which was based on visual assessment. Protease, xylanase, and cellulase are suggested to have a role in plant pathogenesis by S. tritici. Enzyme activity may serve as a measurement of disease severity for assessing the range of susceptibility of wheat cultivars to S. tritici. Une étude, menée sur l’activité enzymatique d’extraits de feuilles de blé inoculées avec Septoria tritici, a révélé l’activité des enzymes suivantes : xylanase, cellulase, protéase et α-amylase. Les niveaux d’activité de la xylanase, de la protéase et de la cellulase étaient étroitement corrélés (P > 0,05) avec les antigènes fongiques mesurés par ELISA et les données visuelles sur la maladie, données recueillies de feuilles infectées provenant d’expériences faites en serre et au champ en 2002 et 2003. Quant aux cultivars de blé testés, les teneurs de ces trois enzymes ont également affiché une bonne corrélation (r = 0,65–0,97) avec les cotes de sensibilité recommandées sur la liste de cultivars du Bundessortenamt (Federal Office of Plant Varieties), cotes basées sur l’évaluation visuelle. La protéase, la xylanase et la cellulase semblent jouer un rôle dans la pathogenèse des plants engendrée par S. tritici. L’activité enzymatique peut servir à mesurer la gravité de la maladie afin d’évaluer le degré de résistance des cultivars de blé à S. tritici. Mots-clés : Septoria tritici, septoriose du blé, ELISA, xylanase, cellulase, protéase.

Seedling and Adult Plant Resistance to Powdery Mildew in Chinese Bread Wheat Cultivars and Lines

Powdery mildew, caused by Blumeria graminis f. sp. tritici, is a widespread wheat disease in China. Identification of race-specific genes and adult plant resistance (APR) is of major importance in breeding for an efficient genetic control strategy. The objectives of this study were to (i) identify genes that confer seedling resistance to powdery mildew in Chinese bread wheat cultivars and introductions used by breeding programs in China and (ii) evaluate their APR in the field. The results showed that (i) 98 of 192 tested wheat cultivars and lines appear to have one or more resistance genes to powdery mildew; (ii) Pm8 and Pm4b are the most common resistance genes in Chinese wheat cultivars, whereas Pm8 and Pm3d are present most frequently in wheat cultivars introduced from CIMMYT, the United States, and European countries; (iii) genotypes carrying Pm1, Pm3e, Pm5, and Pm7 were susceptible, whereas those carrying Pm12, Pm16, and Pm20 were highly resistant to almost all isolates of B. graminis f. sp. tritici tested; and (iv) 22 genotypes expressed APR. Our data showed that the area under the disease progress curve, maximum disease severity on the penultimate leaf, and the disease index are good indicators of the degree of APR in the field. It may be a good choice to combine major resistance genes and APR genes in wheat breeding to obtain effective resistance to powdery mildew.

Chlorophyll and carotenoid content in wheat cultivars as a function of mineral nutrition

Determination of chlorophyll content as an indirect method of estimating the productivity of vegetation represents a good way to gain an understanding of the photosynthetic regime of plants. Physiological investigations of chlorophyll and carotenoid content in the uppermost internode of several wheat cultivars were carried out at the outset of the flowering phase. The dependence of chlorophyll and carotenoid content on the fertilization variant was established at that time. The tested wheat cultivars were grown under conditions of five fertilization variants. The content of chlorophyll a, chlorophyll b, and total chlorophyll (Chl a+b) was measured and carotenoid content was determined on each variant. The results indicate that chlorophyll and carotenoid content depended on the presence and ratio of mineral elements in the substrate. This is demonstrated by the variant with unfertilized soil, where chlorophyll and carotenoid content in all cultivars was lowest. The variant of fertilization with N and P turned out to be most favorable. The next most favorable variant was the one with nitrogen alone, and it was followed by the variant with N and K.

Intraspecific responses in grain quality of 10 wheat cultivars to enhanced UV-B radiation under field conditions

Field studies were conducted to determine the potential for intraspecific responses in grain quality of 10 wheat (Triticum aestivum) cultivars to enhanced ultraviolet-B (UV-B, 280–315 nm) radiation. The plants were exposed to 5 kJ m−2 supplemental UV-B radiation, simulating a depletion of 20% stratospheric ozone. In wheat cultivars tested, intraspecific responses in 16 amino acid contents and total amino acid contents in grains were found. Out of tested wheat cultivars, Dali 905, Mianyang 20, Wenmai 3, Chuxiong 8807 and Huining 18 showed significant increase in proteins, and Yunmai 39 and Huining 18 showed significant increase while Dali 905 and Chuxiong 8807 showed significant decrease in total sugar, respectively. No wheat cultivar showed significant change in rough starch content. Out of 10 cultivars 9 had a positive quality response index (QRI), while only Yunmai 39 showed negative response (QRI −1.19). According to QRI, the tolerance of 10 wheat cultivars to UV-B radiation had the following sequence, Huining 18 > Mianyang 20 > Mianyang 26 > Wenmai 3 > Dali 905 > Longchun 16 > Fengmai 24 > Liaochun 9 > Chuxiong 8807 > Yunmai 39. Intraspecific responses in grain quality of 10 wheat cultivars to enhanced UV-B radiation existed under field conditions.

Intraspecific responses in grain quality of 10 wheat cultivars to enhanced UV-B radiation under field conditions

Field studies were conducted to determine the potential for intraspecific responses in grain quality of 10 wheat ( Triticum aestivum) cultivars to enhanced ultraviolet-B (UV-B, 280–315 nm) radiation. The plants were exposed to 5 kJ m −2 supplemental UV-B radiation, simulating a depletion of 20% stratospheric ozone. In wheat cultivars tested, intraspecific responses in 16 amino acid contents and total amino acid contents in grains were found. Out of tested wheat cultivars, Dali 905, Mianyang 20, Wenmai 3, Chuxiong 8807 and Huining 18 showed significant increase in proteins, and Yunmai 39 and Huining 18 showed significant increase while Dali 905 and Chuxiong 8807 showed significant decrease in total sugar, respectively. No wheat cultivar showed significant change in rough starch content. Out of 10 cultivars 9 had a positive quality response index (QRI), while only Yunmai 39 showed negative response (QRI −1.19). According to QRI, the tolerance of 10 wheat cultivars to UV-B radiation had the following sequence, Huining 18 > Mianyang 20 > Mianyang 26 > Wenmai 3 > Dali 905 > Longchun 16 > Fengmai 24 > Liaochun 9 > Chuxiong 8807 > Yunmai 39. Intraspecific responses in grain quality of 10 wheat cultivars to enhanced UV-B radiation existed under field conditions.

Disease levels in winter wheat, rye and triticale grown on soil artificially inoculated withCephalosporium gramineum

Field experiments with winter cereals grown on soil inoculated withC. gramineum showed that wheat and rye cultivars possess some resistance to the pathogen, while the triticale cultivars were the most susceptible. Higher tolerance of the tested wheat cultivars was connected mainly with slow development of disease symptoms; rye cultivars had, on average, lower percentages of plants infected byC. gramineum. The greatest variation in susceptibility toC. gramineum occurred among the selected cultivars of triticale.

Is Nor region variability in wheat invariably caused by tissue culture?

In a previous study we observed extensive Nor region variability in tissue-culture derived plants of only one out of three tested wheat cultivars. This finding prompted us to further question whether or not this variability was invariably caused by in vitro culture. In the present study, the upper halves of spikes from four source plants of the inbred cultivar 'ND7532' were removed 12 days after anthesis. The immature embryos from these halves were cultured and regenerated into plants. The lower halves of the same spikes were retained on the plants to obtain mature caryopses. DNA was extracted from seedlings, cut with TaqI endonuclease, run on agarose gels, and the respective Southern blots were probed with the plasmid pTA71 to reveal the Nor region patterns. The sexual progeny of regenerants from three out of four source plants derived from the immature embryos provided Nor region patterns which were exactly identical to the patterns obtained from seedlings which germinated from the caryopses matured on the respective source spikes. The regenerants from the fourth source plant provided variable Nor region patterns. Analyses of the Nor region patterns of 21 individual seedlings germinated from caryopses of this source plant showed that 18 had a three-fragment pattern (consisting of 3.0, 2.7 and 1.9 kb fragments) while three seedlings lacked one (2.7 of 1.9 kb) fragment. Furthermore, the next sexual progeny of the regenerants which had a three-fragment pattern further segregated into three- and two-fragment patterns.These results, in conjunction with previous reports on Nor region variability among tissue-culture derived plants, suggest that this variability is not invariably related to in vitro culture.