Improving Quantitative and Qualitative Characteristics of Wheat (Triticum aestivum L.) through Nitrogen Application under Semiarid Conditions

Nitrogen(N),the building block of plant proteins and enzymes,is an essential macronutrient for plant functions.A field experiment was conducted to investigate the impact of different N application rates(28,57,85,114,142,171,and 200 kg ha^(−1))on the performance of spring wheat(cv.Ujala-2016)during the 2017–2018 and 2018–2019 growing seasons.A control without N application was kept for comparison.Two years mean data showed optimum seed yield(5,461.3 kg ha^(−1))for N-application at 142 kg ha^(−1) whereas application of lower and higher rates of N did not result in significant and economically higher seed yield.A higher seed yield was obtained in the 2017–2018(5,595 kg ha^(−1))than in the 2018–2019(5,328 kg ha^(−1))growing seasons under an N application of 142 kg ha^(−1).It was attributed to the greater number of growing degree days in the first(1,942.35°C days)than in the second year(1,813.75°C).Higher rates of N(171 and 200 kg ha^(−1))than 142 kg ha^(−1) produced more number of tillers(i.e.,948,300 and 666,650 ha^(−1),respectively).However,this increase did not contribute in achieving higher yields.Application of 142,171,and 200 kg ha^(−1) resulted in 14.15%,15.0%and 15.35%grain protein concentrations in comparison to 13.15%with the application of 114 kg ha^(−1).It is concluded that the application of N at 142 kg ha^(−1) could be beneficial for attaining higher grain yields and protein concentrations of wheat cultivar Ujala-2016.

Map-based cloning of a novel QTL qBN-1 influencing branch number in soybean[Glycine max(L.)Merr.]

Branch number(BN)is an important agronomic attribute related to the plant architecture,adaptability,and yield of soybean.To date,few studies ofBNhave been conducted to elucidate its genetic background.We aimed to localize genetic factors affecting BN using segregating populations derived fromthe high-branching cultivar‘Kennong24’(KN24)and the low-branching cultivar‘Kenfeng19’(KF19).Composite interval mapping analysis detected a QTL(qBN-1)on chromosome 6 between the SSR markers BARCSOYSSR_06_0993 and BARCSOYSSR_06_1070 using an F2 population.To fine-map qBN-1,a RIL population was developed and genotyped with 14 SSRmarkers located in the QTL region.qBN-1 was localized to a 115.67-kb interval flanked by markers BARCSOYSSR_06_1048 and BARCSOYSSR_06_1053.The QTL was further confirmed using backcross populations of size 1305(BC2F2 with KN24 as a recurrent parent)and 1712(BC3F2 with KF19 as a recurrent parent).The fine-mapping region of qBN-1 contained only two candidate genes,Glyma.06G208800 and Glyma.06G208900,whose expression patterns were investigated by qRT-PCR.Compared to Glyma.06G208800 gene expression,Glyma.06G208900 showed the highest expression of the two genes and showed a significant difference in expression between high-and low-branching genotypes in either axillary meristem or shoot apical meristem,and showed opposite expression patterns in the two tissues at V4 and R1 stages.These results identify Glyma.06G208900 as a novel candidate gene controlling BN.Taken together,the results of this study provide a foundation for cloning and functional analysis of the qBN-1 gene and for the improvement of BN bymarker-assisted selection in soybean breeding.