Biological efficiency of the extract of Haplophyllum perforatum against Tuta absoluta and its influence on the physiological properties of tomato plants

The tomato leaf miner Tuta absoluta (Meyrick) ( Lepidoptera: Gelechiidae ), whose natural range includes the countries of South America, has become widespread in Africa and Europe. Since 2015, the pest has been registered in the Republic of Uzbekistan. It is known to develop resistance to many chemical plant protection products. In addition, pesticides can significantly change the intensity of plant metabolic processes, in particular photosynthesis, which reduces the productivity and quality of the crop. In this regard, plant substances are of interest, the use of which is promising in plant protection. The present work, for the first time, shows the biological effectiveness of the application of the extract of the plant Haplophyllum perforatum against the larvae of the tomato leaf miner in the field. The extract had a positive effect on the content of chlorophylls in tomato leaves and increased the total leaf area of the plant. The aim of our work was to study the biological effectiveness of extract of the plant Haplophyllum perforatum and its complex with the growth regulator Uchkun against larvae Tuta absoluta , as well as their effect on the physiological parameters of tomato. The field experiment was carried out on the area farming facilities “Super Garden” (Tashkent region, Kibray district). Tomato plants of the TMK-22 variety were sprayed with an extract of H. perforatum and its composition with growth regulator Uchkun, which was developed on the basis of polyprenols isolated from cotton leaves. We also used the insecticide of natural origin Proclaim, the active substance of which is 5% emamectin benzoate (Syngenta Crop Protection AG). The seedlings were sown on April 24, 2020. The placement of the plots is randomized, in four repetitions. Spraying was carried out in the phase of the beginning of flowering of tomatoes in the presence of pest numbers not lower than the economic threshold of harmfulness. The design of the experiments was as follows: control (option without treatment), standard Proclaim, 5 % (W.S.G-water-soluble granule, 0.4 kg/ha), extract of H. perforatum , 1.0 % (W.E-water emulsion, 0.4 kg/ha), composition - H. perforatum extract, 1.0 % + Uchkun, 0.0001 % (W.S.E, 0.4 kg/ha). The biological effectiveness of the extracts was evaluated by reducing the number of pest larvae. For 1 day before treatment, on days 3, 7 and 14 after treatment, larvae of the 1st-2nd and 3rd-4th in stars were counted. The content of chlorophylls was estimated by the spectrophotometric method. During the growing season, biometric indicators were recorded: leaf surface area, plant height, number of leaves, flowers and fruits. The total leaf surface area was determined by the gravimetric method. We have revealed high toxicity of the H. perforatum extract and its composition with the Uchkun preparation against the tomato leaf miner. The greatest decrease in the number of pest larvae occurred on day 7 after spraying tomatoes. Against an increase in the number in the control, the effectiveness of the extract against larvae of the 1st-2nd instar was 87.1 %, of the 3rd-4th instar - 77.5 %. For the treatment with the composition (84.1 and 70.0 %) and the insecticide (87.0 and 70.0 %), the efficiency was almost comparable. Treatment of plants with the studied solutions contributed to an increase in the content of photosynthetic pigments in damaged leaves. After exposure to the extract, the content of chlorophyll a was higher than the control by 1.1 times, chlorophyll b - by 1.8 times, their sum - by 1.5 times, after treatment with the composition, the amount of chlorophyll a and b exceeded the control by 2.2 and 2.1 times, their sum - by 1.7 times. An increase in leaf surface area was also observed: after treatment with H. perforatum extract, the indicators were higher than the control by 75.0 %, with the composition - by 58.3 %, the number of leaves increased by 85.1 and 89.9 %, respectively. In the variant with the use of the extract, the number of flowers was 8.3 pcs/plant, fruits - 3.8 pcs/plant, when treated with the composition - 8.9 and 4.1 pcs/plant, with Proclaim - 7.8 and 3.5 pcs/plant, in the control - only 2.2 and 1.2 pcs/plant. Thus, we have shown the possibility of using the plant extract of H. perforatum against the tomato leaf miner. It has been established that treatment with a composition of H. perforatum extract with a growth regulator improves the physiological and biochemical parameters of tomato plants.