Effects of Weak- and Semi-Winter Cultivars of Wheat on Grain Yield and Agronomic Traits by Breaking through Traditional Area Planting

Global warming has changed the suitability of areas traditionally planted with crops, raising concerns about cereal security. To investigate the possibilities and constraints of increasing yields by breaking through traditional area plantings of wheat cultivars, a two-year field experiment was conducted in southern and northern locations in the Yangtze River basin (YRB), China (separated by approximately 180 km), with seven weak-winter types and six semi-winter types, respectively, bred for the two regions. The movement of weak-winter-type cultivars to the north increased or did not change grain yield and their grain yields were not significantly higher than those of local semi-winter-type cultivars. The movement of semi-winter-type cultivars to the south significantly decreased their yields. Thus, breaking through traditional area plantings did not significantly increase grain yields compared with those of local wheat cultivars. Grain yield of wheat planted in the northern YRB was higher by 5 to 20% than that in the southern YRB because of an increase in spikes that resulted from a longer spike formation phase. In addition, the post-anthesis leaf area declined more slowly in the northern YRB because of higher main stem and tiller survival. High-yielding cultivars always had more spikes and larger photosynthetic areas after anthesis than those of low-yielding cultivars regardless of the planting locations, which led to increases in post-anthesis biomass. However, the grain yield of different cultivars was highly variable under different environmental conditions. The coefficient of variation (CV) of grain yield in different cultivars was significantly positively correlated with the CV of spike number and post-anthesis biomass, implying that flexibility spike number and post-anthesis biomass in response to environmental changes can maximize release of yield potential. Therefore, improving main stem and tiller survival can increase spike number and maintain post-anthesis photosynthetic areas and help to establish a large, highly stable, and productive population with a high level of suitability and production through effectively utilizing the resources during the late growth phase. Valuable suggestions for breeding high-yield and -stability cultivars and confirming their planting range in the future are given.

Evaluation on Potential Risk of the Emerging Yr5-Virulent Races of Puccinia striiformis f. sp. tritici to 165 Chinese Wheat Cultivars

In 2017, a new race (TSA-6) of the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici, virulent to resistance gene Yr5 were detected in China. However, whether Chinese wheat cultivars are resistant to the new races was unknown. In this study, two isolates (TSA-6 and TSA-9) with virulence to Yr5 were tested on other wheat Yr gene lines for their avirulence/virulence patterns and used, together with prevalent races CYR32 and CYR34 without the Yr5 virulence, to evaluate 165 major Chinese wheat cultivars for their reactions. Isolates TSA-6 and TSA-9 had similar but different virulence spectra, and therefore should be considered as two different races. Their avirulent/virulence patterns were remarkably different from that of CYR34 but quite similar to that of CYR32. Of the 165 wheat cultivars, 21 had all-stage resistance to TSA-6, 34 to TSA-9, and 20 to both races. Adult-plant resistance (APR) was detected in 35 cultivars to TSA-6 and 27 to TSA-9, but only 3 cultivars showed APR to both new races. Slow rusting resistance was observed in 24 cultivars to TSA-6 and of 33 to TSA-9. Analysis of variance (ANOVA) of disease index indicated a significant difference among cultivars, but not among the four races. Based on the molecular marker data, a low percentage of wheat cultivars carried Yr5, Yr7, Yr10, Yr15, Yr26, and/or YrSP. As TSA-6 and TSA-9 can be a serious threat to wheat production in China, monitoring TSA-6, TSA-9, and other races are continually needed.

Production and nutritional value of wheat and triticale cultivars in different harvest times in the Minas Gerais semiarid

The objective of the present study was to evaluate the productive performance and nutritional value of forage of wheat and triticale cultivars at different harvest times in the semiarid region of Minas Gerais. Eight wheat cultivars and two triticale cultivars harvested at three stages of plant development were evaluated: Rubberization, grain at the stage of soft mass and harvest maturation. The experimental design adopted was a randomized block in a factorial scheme 10 × 3, with three replicates, 10 cultivars and 3 developmental stages for plant collection. The main agronomic characteristics and nutritional value were evaluated of forage of the cultivars under study. The study demonstrated the potential of wheat and triticale cultivation for forage in the semiarid region of Minas Gerais. The mean dry matter yield of wheat cultivars was 5.90 t ha-1, 7.85 t ha-1 and 7.98 t ha-1 and triticale 6.47 t ha-1, 9.97 t ha-1 and 10.5 t ha-1 for the rubber harvesting stages, grain at the stage of soft mass and harvest maturation, respectively. For the average crude protein content, the wheat cultivars showed 15.07%, 9.13%, 10.60% and the triticale cultivars showed 14.4%, 9.31% and 10.05% for the harvest stages of rubber formation, grain at the stage of soft mass and harvest maturation, respectively. When evaluating the average levels of total digestible nutrients, the wheat and triticale cultivars showed an average of 48.90% and 48.67% in the rubber harvesting stage and 42.68% and 49.60% in the grain in the mass stage suave and 44.43% and 42.90% at harvest maturation. The highest yield of digestible dry matter was observed with the cultivars harvested at the grain stage at the soft mass stage. Triticale IPR 111 and Wheat IPR PANATY had greater productive potential and better nutritional quality for use as forage.

Fusarium head blight resistance exacerbates nutritional loss of wheat grain at elevated CO2

The nutritional integrity of wheat is jeopardized by rapidly rising atmospheric carbon dioxide (CO2) and the associated emergence and enhanced virulence of plant pathogens. To evaluate how disease resistance traits may impact wheat climate resilience, 15 wheat cultivars with varying levels of resistance to Fusarium Head Blight (FHB) were grown at ambient and elevated CO2. Although all wheat cultivars had increased yield when grown at elevated CO2, the nutritional contents of FHB moderately resistant (MR) cultivars were impacted more than susceptible cultivars. At elevated CO2, the MR cultivars had more significant differences in plant growth, grain protein, starch, fructan, and macro and micro-nutrient content compared with susceptible wheat. Furthermore, changes in protein, starch, phosphorus, and magnesium content were correlated with the cultivar FHB resistance rating, with more FHB resistant cultivars having greater changes in nutrient content. This is the first report of a correlation between the degree of plant pathogen resistance and grain nutritional content loss in response to elevated CO2. Our results demonstrate the importance of identifying wheat cultivars that can maintain nutritional integrity and FHB resistance in future atmospheric CO2 conditions.