The possibility of selecting spring rape for cold tolerance at the mature pollen grain stage was studied by investigating the effects of pollen storage at low temperatures on the quality of pollen grains and on the cold tolerance of the plants generated from them. Pollen treatments of F, hybrids affected fertilization ability much more than viability and even after 10 days storage at 3 or 10°C the pollen germination percentage was reasonably high. Pollen storage for 7 or 10 days at 3 or 10°C significantly increased the cold tolerance of F2 seed germination, with 3°C being more effective. Pollen storage for a shorter time had no effect upon the number of resulting genotypes tolerant to low temperature. This approach may be successfully apphed in plant breeding to enrich segregating plant populations with cold-tolerant genotypes.
The frequency and spectrum of morphological and physiological mutations obtained in M 2 and M 3 generations after sunflower immature embryos treatment with ethyl methanesulphonate (EMS) have been studied. Immature 9 -10 and 14 -15-day-old embryos of two genotypes were treated with EMS at the concentration of 0.02% for 16 hours. Thirty-three types of mutation were found, described, and classified into the following groups: chlorophyll deficiency (3 types), cotyledon mutation (1), leaf mutations (6), stem mutations (9), inflorescence mutations (11), seed mutation (1) and physiological mutations (2). Differences were observed between genotypes for the spectrum and frequency of mutation. Mutation frequency after immature embryo treatment in the M 2 generation did not exceed the amount of mutations in M 3. At the same time, some mutations such as sterility, leaf venation, and different shapes of leaf lamina were unique for the M 3 generation. Morphological mutations were rarest after mutagen treatment of immature 9 -10-day-old embryos.Key words: sunflower, ethyl methanesulphonate, immature embryos of different age, morphological and physiological mutations, mutation spectrum and frequency
The effects of high temperature on mature pollen of various maize lines were investigated. Genotypic differences in pollen reaction to high temperature were revealed. Pollen grains resistant to high temperature (35 ° C, 26 ° C) were characterized by higher germination capacity and better ability to develop normal pollen tubes. The studies are of interest to evaluate reproductive system tolerance and conduct gamete selection at the mature pollen grain stage in maize.
The drought resistance and genetic structure of F2 sporophytic populations for some morphological marker traits after pollen selection for water stress tolerance in F1 sunflower hybrids has been studied. The emasculated inflorescences were moistened with 10% and 20% of PEG 6000 solution in the experiments and with distilled water in the control. Freshly collected pollen was used for pollination after drying up the PEG solution on stigmas. F2 resulted seeds were germinated in 20% solution of PEG 6000 for a period of 3 days, and then the percentage of seed germination was counted. Germinated and not germinated seeds were separately planted. Segregation ratios in F2 populations for leaf venation and leaf chlorophyll deficiency marker traits were analyzed at early stage of development. Pollen treatment significantly increased the drought resistance of F2 populations and changed the monogenic ratios for leaf chlorophyll deficiency marker trait.
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