Optimized gamma radiation produces physiological and morphological changes that improve seed yield in wheat

To study the effect of gamma radiation on various morphological and agronomic characters of bread wheat (Triticum aestivum L.), seeds were subjected to different gamma radiation doses; and selected M₅ and M₆ generation lines were evaluated. The optimum doses to induce desirable changes in bread wheat were 100-200 Gy. Seed loss decreased while grain yield, yield components, fertile florets number, biological yield, plant height, harvest index and flag leaf area increased in all mutant lines. Shear strength increased in many lines. Selected mutant lines also showed reduced seed shattering that can greatly reduce seed loss at harvest. Some new phenotypic characters such as the appearance of bristles on the glume, important for drought tolerance, two spikelets at each rachis and more fertile florets at each spikelet. These can greatly increase yield, as seen in some mutant lines. Also, some physiological characteristics including photosynthetic rate, stomatal conductance, water use efficiency, and chlorophyll content improved in some mutant lines. About 95.8% of the total variation in grain yield was explained by three selected variables: flag leaf area, number of seeds per spike, and spike number per plant. Grain yield increased more than 45% in some mutant lines the highest ever reported using this approach to the genetic improvement of wheat. Wheat grain yield has increased 2.2 times in the last 50 years, which indicates that if mutagens are optimally used and the selection is carefully performed as described herein, it is possible to improve important economic traits, in a much shorter time.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12298-022-01225-0.

Genotypic differences relative photochemical activity, inorganic and organic solutes and yield performance in clones of the forage cactus under semi-arid environment

Plants with the crassulacean acid metabolism commonly present good adaptation to arid and semi-arid environments, but it highly depends on the type of species. In this study, chlorophyll fluorescence, the concentration of inorganic and organic solutes and the productive performance were evaluated along with their relationships in different clones of the genera Opuntia and Nopalea. The experiment was conducted from 2016 to 2018. Four clones of genus Opuntia were evaluated: 'Orelha de Elefante Mexicana' (OEM), 'Orelha de Elefante Africana' (OEA), V19 and F8; and two clones of genus Nopalea: 'IPA Sertânia' and 'Miúda'. The experiment was arranged in a randomised block design, with six treatments and three replications. The following parameters were measured when harvesting: initial, maximum and variable fluorescence; the quantum yield of PSII (Fv/Fm); light-induction curves of the photochemical parameters (ΔF/Fm', qP, NPQ and ETR); the chlorophyll and carotenoid content; carbohydrates; the sodium (Na⁺) and potassium (K⁺) content; morphometry; and dry matter accumulation. The values for the effective quantum yield of PSII (ΔF/Fm') and the alterations in photochemical quenching were higher in the OEM clone (P < 0.05). There was a difference between clones for non-photochemical quenching, with the F8 clone having the highest values. The Fv/Fm was 0.87 for the OEM. 'IPA Sertânia' obtained the greatest Chl a/b, and the highest values for carbohydrate concentration were found in the OEA clone. The OEM clone showed the greatest accumulation of K⁺, in addition to a higher cladode area index and greater dry matter accumulation. The results of this study show the high physiological tolerance of the forage cactus to a semi-arid environment, which varies according to the clone.