ADAPTIVE POTENTIAL OF THE GENE POOL OF LEAF LETTUCE, CREATED BY THE METHOD OF INDUCED MUTAGENESIS ON THE BASIS OF THE DOMESTIC CULTIVAR VELMOZHA

Abstract

 In today's global climate change, the main task of vegetable plant breeding is the creation of new varieties and hybrids F₁ with increased potential for adaptation to stressful conditions of cultivation. Success in solving the task depends on the level of studying the source material, the breeding of parent pairs for hybridization, optimization of the breeding method for adaptability by adhering to the principles of selection of initial forms on the basis of traits which closely correlated with adaptability. According to A. A. Zhuchenko, the ability of certain types of plants to withstand the actions of local stress factors of the environment has a definite influence on their geographical distribution and the formation of the structure of the crop. According to the analysis of works of P. P. Litun the main object of adaptive breeding is macrosystem of plants, which formed its micro and macro traits under the background of the phenotypic manifestation of the production process. To determine the adaptive reaction, one must generalize the nature and mechanism of growth, development and formation of plant populations. On the basis of conducted research on the testing of genotypes in various natural environments, A. V. Kilchevsky and L. V. Khotylyov developed a method of genetic analysis, which reveals the general and specific ability of genotypes, their stability and selective value, as well as to select them for adaptive ability depending on the set breeding purpose. On the basis of the proposed method, the authors of the article analyzed the gene pool of the salad of seedlings, created by methods of induced mutagenesis and analytical selection in the agroclimatic zone of the Northern Forest-steppe of Ukraine. The results presented in this publication are a logical continuation of the above studies.

The purpose of investigation. Analysis of the adaptive properties of the leaf lettuce gene pool, created by the method of induced mutagenesis and the allocation of valuable sources for varietal's breeding in conditions of the agroclimatic zone of the Eastern Forest-steppe of Ukraine.

Methods. Object of research: lettuce varieties (Lactuca sativa L. var. secalina). Subject of research: 8 mutant samples of lettuce progeny M₂-M₄ created by pre-sowing treatment of seeds by γ-radiation in three doses (7, 11 and 15 kiloRentgen (kR)) and by soaking in aqueous solutions of biologically active substances of mutagenic action at an active concentration 0,02 % and for different exposures – 3, 6 and 18 hours. In the experiment, as a standard, the known drug mutagenic action – dimethyl sulfate (DMS) and its closest chemical analogues – preparations DMU-1, DMU-5 and DMU-6, were synthesized at the Institute of Bioorganic Chemistry and Petrochemistry of the National Academy of Sciences of Ukraine. The experiment was carried out with Velmozha variety on the experimental basis of the Institute of Vegetable and Melon of the National Academy of Agrarian Sciences of Ukraine, which is located in the zone of the Eastern Forest-Steppe of Ukraine. In 2011, on the basis of the Velmozha variety, seeds of the mutant generation of M₁ lettuce were obtained. During 2012-2014, the study of mutant progeny M₂-M₄ was continued for the phenology of growth and development of plants and a set of quantitative and qualitative characteristics.

Results and Discussion. At the time of the completion of field research in 2014, the mutant samples of leaf lettuce had a progeny of M₄.

At the time of the completion of field studies in 2014, the mutant samples of leaf lettuce were genera M4 (Table 2). Depending on the aftermath of the mutagenic factor, the following mutant genotypes were identified: [Velmozha (DMS, 6 h.), mf-1] (K-7391 (1)); [Velmozha (DMS, 6 h.), mf-2] (K-7391 (2)); [Velmozha (DMS, 6 h.), mf-3] (K-7391 (3)); [Velmozha (DMS, 18 h.)] (K-7394); [Velmozha (DMS, 18 h.)] (K-7395); [Velmozha (DMU-1, 3 h.), mf-1] (K-7386 (1)); [Velmozha (DMU-1, 3 h.), mf-2] (K-7386 (2)); [Velmozha (DMU-1, 3 h.)] (K-7387); [Velmozha (DMU-1, 3 h.), mf-1] (K-7412 (1)); [Velmozha (DMU-1, 3 h.), mf-2] (K-7412 (2)); [Velmozha (DMU-1, 3 h.), mf-3] (K-7412 (3)); [Velmozha (DMU-1, 3 years), mf-4] (K-7412 (4)); [Velmozha (DMU-5, 6 h.)] (K-7418); [Velmozha (7 kP)] (K-7400); [Velmozha (7 kP), mf-1] (K-7401 (1)); [Velmozha (7 kP), mf-2] (K-7401 (2)).

On the trait of "Yield" 2 mutant samples statistically significantly exceeded the original form at 42,99-62,93 %. The highest yield was observed for the sample [Velmozha (DMS, 6 h.), mf-2] (K-7391 (2)) – 12,66 t/ha at 7,77 t/ha in the original form.

The following parameters were used to determine the adaptive potential of the mutant samples of leaf lettuce: “GAC” (general adaptive capacity); “SAA” (specific adaptive ability); “Sg_i” (relative stability of the genotype); “b_i” (coefficient of regression of the genotype on the medium or coefficient of plasticity); “SVG_i” (selective value of the genotype).

As a result of the statistical calculations of the results of 3 years of field research, 3 mutant specimens were distinguished, which had better positive meanings of the “STG_i” indicator on the trait of "Yield" from 8,36 to 9,95 t / ha: [Velmozha (DMU-5, 6 h.)] (K-7418); [Velmozha (DMU-1, 3 hours), mf-1] (K-7386 (1)); [Velmozha (7 kP)] (K-7400). This indicator for the original form was 7,23.

According to the results, seven mutant samples of leaf lettuce isolated in which the value of the coefficient of plasticity was less than unity (0.79 < b_i < 0,94) and which included genotypes with a low reaction to growing conditions and the influence of environmental factors. Including the initial form, the yield of leaf mass in this samples of mutant genotypes varied within 7,06-8,31 t/ha.

The second group included mutant genotypes of leaf lettuce, for which the value of the coefficient of environmental plasticity was greater than unity (1,10 < b_i < 1,43). That is, these samples refer to the intensive type of cultivation, since they demonstrated high sensitivity of climatic conditions and dependence on the agronomic condition of cultivation, respectively. 4 samples were included in this group, which were distinguished by the highest yield at the level of 9,63-12,66 t/ha.