Pre-sowing seed treatment of biofertilizers as a means of stimulating growth and physiological and biochemical processes in the tomato varieties of plants

Abstract

The aim is to evaluate the effectiveness of the influence of pre-sowing treatment of seeds with bio-fertilizers (both microbiological and derivatives of natural humic substances) on functional processes, growth and development of tomato plants.

Methods. The objects of research were determinant tomato varieties of Ukrainian selection, namely, Chaika, Eleonora and Talan, which vary in resistance to bacteriosis pathogens. In the capacity of liquid complex bio-fertilizers they were used: Agro-Bac Plus, which contains the bacteria Bacillus subtilis M4, titre 1х108 CFU/g of the preparation; Rost Kontsentrat – 12 - 14% of potassium humate, micro and macro-elements, natural stimulants, vitamins, antibiotics and biologically active substances: N, P, K, Ca, Mg, S, Fe, Cu, Zn, Co, Mo, B. Tomato seeds were soaked at a temperature of 20-22° C and a relative humidity of 50% in bio-fertilizer solutions at concentrations recommended by the manufacturer to stimulate the process of transition from embryo dormancy to active growth and development. For control we soaked the seeds in sterile water. The seeds were placed in an incubator for germination at a temperature 20-24° C. We determined the number of sprouted seeds on the 3^rd, 5^th, 10^th and 14^th days, and weight and length of the formed seedlings – on the 14th day. The number of seeds that germinated on the 3^rd-5^th day (the first registration) was considered to be the laboratory vigor, and those which sprouted in 10-14 days (the second record) – the viability. Graphic of the dynamics of tomato seed germination was expressed as asymmetric logistic curve to within 0.9999, which was described by Gompertzian’s function. In the leaves of the plants of tomato varieties they tested the content of chlorophyll “a” at the wavelength of 662 nm and chlorophyll “b” – 644 nm, carotenoids “k” – 440 and 644 nm according to a conventional method with spectrophotometer Optizen POP. The concentration (C) of photosynthetic pigments in leaves was counted in mg per g of wet weight of the substance. Peroxidase enzyme activity of tomato seedling was measured with spectrophotometric method according to the optical density of the reaction products formed by oxidation of benzidine, every second for 120 s. at wavelength of 590 nm.

Results. Application of bio-fertilizers caused significant stimulating effect on tomato seed vigor on the 3rd day. Thus, on average for control vigor on the 3^rd day was 30%, for the variant with fertilizer Agro-Bac Plus – 34%, and Rost Kontsetrat – 44%. Depending on the variant of the experiment the indices of Gompertzian’s function changed. A fluctuation of A-indices in terms of the treatment with bio-fertilizers was in the range of 44.14 to 98.18, which confirms the high biological potential of tomato seeds to absolute germination, which was 84-94%. The indicator of the rate of germination process (v) of tomato seeds was the maximum – 0.6807 in terms of treatment with Rost Kontsetrat micro-fertilizer. The obtained results confirm the fact of increasing intensity of processes of germination of the treated tomato seeds by 23-25% when compared to the control. Bio-fertilizers significantly stimulated the growth of roots and shoots. The height of tomato plants under control without the use of bio-fertilizers was 47 ± 3.8 mm. The most pronounced effect on plant height (66±7.2 mm) was provided by the use of fertilizer Rost Kontsetrat based on derivatives of humic substances of natural origin. One of the indicators of the efficiency of biologics and micronutrients is the intensity of photosynthesis and, consequently, the accumulation of organic matter by plants. Therefore, the study of the dynamics of accumulation of chlorophyll in the leaves of tomato plants under the influence of biological factors is important, as the content affects the rate of photosynthesis and other physiological processes. While studying chlorophyll and carotenoids in the leaves of studied tomato varieties and calculation of the ratio, it was found variety based specificity and physiological dependence of these parameters on the conditions of germination of seeds. For extracts of leaves of tomato varieties under these conditions the maximum light absorption in acetone was in spectral frequency of 435 and 635 nm, characteristic for chlorophylls. In the variant without the use of bio-fertilizers chlorophyll content in leaves of tomato varieties was 1.7-2.23 mg/g, and carotene – 0.7-0.83 mg/g (Table 3). Use of the fertilizer Agro-Bac Plus based on microorganisms provided the increase of chlorophyll content by 115.0-130.9%, and of carotene – by 114.5-147.1%, when compared to the control. Appliance the fertilizer Rost Kontsetrat, derivatives of naturally occurring humic substances, also led to increase of their number by 138.8-183.8% and 146.1-157.8%. A high total content of chlorophylls a + b (2.23 ± 0.08 mg/g) in the leaves of the Chaika variety, which is characterized by increased resistance against bacteriosis pathogens, is ensured by effective functioning of the photosynthetic apparatus of assimilation organs. For this variety, this index was the highest in terms of treatment with bio-fertilizers Agro-Bac Plus – 2.91 ± 0.05 mg/g, and Rost Kontsetrat – 4.10 ± 0.09 mg/g. A similar pattern was also noticed in terms of the change in the number of carotenoids. It is obvious that the ratio of chlorophyll content to carotenoids is one of the integrated physiological characteristics of plant resistance against biological and abiotic environmental factors. Our studies showed that peroxidase activity in leaves of tomatoes after treating with bio-fertilizers increases when compared to the control. Increased activity of peroxidase in plant tissues under bio-fertilizers indicates the efficiency of the use of these compounds to correct breathing intensification and immunity of plants. The highest activity of the peroxidase enzyme was defined in terms of the use of bio-fertilizer based on B. subtilis, and was 135% when compared to the control. In terms of the use of the fertilizer Rost Kontsetrat, peroxidase activity was increased by 112.5% when compared to the control.

Conclusions. Bio-fertilizers Agro-Bac Plus and Rost Kontsetrat cause an increase in vigor and germination of seeds of the studied tomato varieties by 23-25% when compared to the control. Treatment of seeds with bio-fertilizers causes an increase in chlorophyll content by 15-83.8%, and carotenoid content by 14.5-57.8%, leading to an intensification of photosynthesis and respiration. Increased activity of peroxidase by 12.5-35% in the leaves of tomato varieties under the influence of bio-fertilizers Agro Buck Plus and Rost Kontsetrat confirms the effectiveness of their use for activation of growth processes and the immunity of plants.