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Colchicine is a substance used to induce mutations in order to regulate important agronomic traits. The genotypes Pavlodarskoe 4, Quartet, and PI 289324, originating from Kazakhstan, the Russian Federation, and Hungary, respectively, were used as materials. The objective of this study was to investigate the effects of different colchicine concentrations (0.0, 0.04, 0.06, 0.08, and 0.1%) and treatment times (6, 12, and 24 h) on the agronomic traits of proso millet (Panicum miliaceum L.) and to assess the genetic diversity of the M2 generation using inter simple sequence repeat (ISSR) markers. The experiment was conducted in 2021 for the M1 generation and in 2022 for the M2 generation, from May to September. The percentage of field germination decreased with increasing colchicine concentrations and exposure durations. The mean field germination percentages were 48.57% in Pavlodarskoe 4, 43.28% in Quartet, and 53.14% in PI 289324 under colchicine treatment. Chlorophyll-defective M1-M2 plants were obtained using various colchicine concentrations and exposure periods. The highest number of mutational modifications was attained with the 0.08–0.1% concentrations of colchicine. Based on the research results, a total of 248 plants with chlorophyll-defective mutations were selected from 2214 plants. The growing seasons of M1 and M2 plants were shortened by higher colchicine concentrations (0.08–0.1%) combined with soaking times of 12 and 24 h. Thus, the longest growing season (84 days) was observed with a 6 h treatment time for PI 289324, while the shortest (78 days) was recorded for 12 and 24 h treatments. The possibility of obtaining morphological mutations using colchicine has been confirmed. The ISSR primers amplified a total of 1333 fragments; 1281 bands were found to be polymorphic, and 52 bands were monomorphic. The percentage of polymorphism varied from 80 to 100%, with an average of 96.11%. Most of the different allelic bands were detected when applying the 0.08% colchicine concentration. These positive variations are a great opportunity to use colchicine as a tool for improving agronomic traits in plant breeding. [ABSTRACT FROM AUTHOR]

Rht4 is characterized as a GA‐responsive dwarf gene in bread wheat (Triticum aestivum L.). The responsiveness of Rht4 to exogenous GA3 was characterized in seedlings, but the effects of exogenous GA3 on the important morphological and agronomic traits such as plant height, grain‐filling rate, and yield components are unclear. In this study, the Rht4 responsiveness of exogenous GA3 on these traits was evaluated using the homozygous F4:5 and F5:6 lines derived from a cross between Jinmai47 and Burt ert937 (Rht4 donor). After exogenous GA3 application, the plant height of the dwarf lines was, on average, increased by 17.54%, about 7.92% more than that of the tall lines. Compared with the tall lines, application of exogenous GA3 significantly increased the kernel weight, maximum grain‐filling rate (Gmax), average grain‐filling rate (Gave) and kernel weight increment achieving Gmax (Wmax) in both superior and inferior grains, while the day on which the maximum grain‐filling rate was reached (Tmax) in Rht4 dwarf lines was significantly earlier in the two generations. What is more, the grain number spike−1, grain yield plant−1, and 1000‐kernel weight (TKW) of the dwarf lines notably increased after exogenous GA3‐treatment, while there was no significant change in the tall lines except for TKW. The quality traits of the dwarf lines with GA3‐treatment were greatly improved. Taken together, these results suggested that the application of GA3 could improve the grain‐filling process of Rht4 and compensate for some negative influences, which may provide a reference for its application in wheat breeding and promote the characterization of its regulatory mechanisms. [ABSTRACT FROM AUTHOR]

Rht14, was considered as a GA‐responsive dwarf gene in durum wheat (Triticum durum L.). The object of this paper is to understand the responsiveness of Rht14 after applying exogenous GA3 on important morphological and agronomic traits, and its potential application in wheat breeding. In this study, the F2:3 lines, F3:4 lines and F4:5 lines derived from the reciprocal crosses between the Castelporziano (CP), the donor of Rht14, and tall cultivar Langdon (L) were used to evaluate the effects of Rht14 with exogenous GA3 application on crucial traits. After application of GA3, the plant height of the dwarf lines was more significantly increased by an average of 51.21% and 52.27% than that of the tall lines by 14.70% and 15.16% of the two populations, respectively, while their diameter and thickness of internodes were remarkably reduced, and their flag leaf area, SPAD value and net photosynthetic rate were markedly decreased, compared with the controls. After application of GA3, the spikelet number spike−1, grain number spike−1, and 1000‐kernel weight of the dwarf lines notably increased, while no significant differences were observed on the seed length, width and thickness. Exogenous GA3 significantly increased the coleoptile length, whereas notably reduced the max root length and total root length of the dwarf lines. Significant increases of crude protein, wet gluten, sedimentation value, stability time and development time were observed in the dwarf lines treated with GA3. This study indicated the dwarf gene Rht14 was a GA‐deficient gene and application GA3 could rescue some negative effects by Rht14. [ABSTRACT FROM AUTHOR]