Influence of nanopreparations on laboratory seed germination, growth, development and yield of cotton (Gossypium hirsutum L.)

Currently, an important role is given to technologies based on a wide range of environmentally friendly plant protection products. The nanopolymer bioactive preparations based on chitosan from the silkworm ( Bombyx mori Linnaeus, 1758) pupae with fungicidal and bactericidal properties are well suited for pre-sowing treatment of crop seeds. Here, for the first time, it was revealed that the seed treatment with nanopolymer preparations containing copper and silver ions accelerates the growth and development of seedlings and increases the yield of cotton cultivar Andijan 36. Our aim was to evaluate the effect of biologically active nanopolymer complexes based on chitosan and its derivatives on the morphophysiological and sowing parameters of seeds, the economically valuable qualities of raw cotton, and the yield of cotton in lab tests and under field conditions (the Research Institute of Selection, Seed Production and Agro-Technology of Cotton Growing, 2018-2020). In the experiments, we used nanopolymeric preparations PMC (polymer-metal complex) Cu2+:Ag 7:3, PMC Cu2+:Ag 8:2, Na-nochitosan (NanoChS, 0.5 %, 90 kDa), Nanoascorbachitazan (NanoAChS, 0.5 %, chitosan:ascorbic acid 4:1) and polymer preparations Chitosan initial 0.5 %, Kuprimhit 0.5 %, Ascorbatchitosan (AChS). Preparations UZKHITAN (Institute of Chemistry and Physics of Polymers of the Academy of Sciences of the Republic of Uzbekistan) and Dalbron (Dalston associated SA, Panama) served as standards, seeds without processing served as control. Seeds ( n = 36) of cotton ( Gossypium hirsutum L.) cultivar Andijan 36 were soaked in preparations (at the rate of 20 l/t seeds) at least 3-4 days before sowing. In each variant of the experiment, 6 kg of cotton seeds were treated. In lab tests, the seeds were germinated in sand at 25 °С and a 60-65 % air humidity. Germination energy was determined on day 4, germination on day 12. The length of the aboveground and underground parts of the seedlings was measured on days 3, 5, 7, 9, and 10. Field experiments were carried out at the experimental farm of NIISSAVKh (Tashkent region, Kibray district, Salar settlement). The emergence of seedlings was registered, field germination was assessed, and phenological observations were made over the plant growth and development period from June 1 to September 1. To assess the economically valuable characteristics of raw cotton (fiber yield, weight per box, fiber length), test samples were collected before harvesting. Yields were recorded on September 15, October 1, October 15, and November 1. In lab tests, the seeds treated with PMC Cu2+:Ag 8:2, NanoAChS 0.5 %, 4:1 or PMC Cu2+:Ag 7:3 had the best germination rate, the 96.0, 96.0, and 97.0 %, respectivey, that exceeded the control by 4.0-5.0 % and the Dalbron standard by 2.0-3.0 %. The aboveground part of the seedlings with NanoAChS treatment turned out to be 0.6-4.6 mm longer than that with AChS, the underground part was 0.1-2.1 mm longer. The differences between NanoChS and Chitosan were 0.3-2.1 mm and 0.8-2.3 mm, respectively, between PMC Cu2+:Ag 8:2 and Kuprumhit - 0.3-4.1 mm and 0.1-2.7 mm. On days 3, 5, 7, 9, and 10, plants from seeds treated with nanopolymer preparations outperformed those threated with polymer preparations. PMC Cu2+:Ag 8:2, NanoAChS and NanoChS had a more pronounced effect on seed germination and length of the aboveground and underground parts of the seedlings than their polymer counterparts. In field tests, the best indicators of growth and development were recorded for PMC Cu2+:Ag 8:2, PMC Cu2+:Ag 7:3, and NanoAChS 0.5 %, specifically, the plant height on September 1 exceeded the control by 7.4; 8.0; 7.7 cm, the number of sympodial branches by 1.5; 1.2; 0.6 pcs, the number of boxes by 2.4; 1.8; 2.5 pcs. Also, upon seed treatments with PMC Cu2+:Ag 8:2 and PMC Cu2+:Ag 7:3, the cotton yields exceeded the control by 4.0 and 3.7 c/ha, respectively, and the Dalbron standard by 3.3 and 3.0 c/ha. A trend towards higher yields was observed from the first crop count. Therefore, nanopolymeric preparations PMC Сu2+:Ag 7:3 and PMC Сu2+:Ag 8:2 can be used for cotton seed encapsulation.