EFFECT OF VARIOUS STRAW/MANURE RATIOS IN SYSTEMS WITH EARTHWORMS Eisenia fetida ON LETTUCE GROWTH PARAMETERS AND SUBSTRATE QUALITY

Abstract

Background. At present, there is an increase in demand for natural agricultural products, which is contributing to the development of plant production in artificial ecosystems that function according to the principles of natural cenoses, with a certain flexibility to emerging stresses. Organic wastes can be incorporated into biosphere-like system compositions in the presence of decomposers, which include earthworms that increase the productivity, environmental sustainability, and self-regulating capacity of agroecosystems. Purpose. The purpose of our research was to investigate the effect of wheat straw/ cattle manure ratios in model systems with peat substrate and earthworms on lettuce productivity and vegetative growth parameters, chemical composition of plants and substrates, as well as worm population. Materials and methods. In laboratory experiments, we evaluated the effect of applying organic wastes (various wheat straw/cattle manure ratios) to peat substrate with introduced earthworms (Eisenia fetida) (10 individuals/800 g substrate) on lettuce (Lactuca sativa Credo cultivar lettuce plants). At the experiment’s end, each plant’s height, leaf area, aboveground biomass (fresh and dry), and photosynthetic pigment content were measured; chemical analysis of substrates and plant mass was carried out; worm adaptive capacity was evaluated according to morphofunctional characteristics; worm fecundity and coprolite output were calculated; the number of bacteria and micromycetes was counted, and Azotobacter activity was estimated. All experiments were performed in three independent biological replicates. Statistical analysis was performed using the application package Statistica 10.0 (StatSoft, USA). Results. Incorporating of various straw/manure ratios into the substrate enhanced the productivity of lettuce plants: the edible surface area, plant weight and photosynthetic pigment content increased. This also contributed to a significant change in the content of mobile forms of major nutrients in the substrate, as well as to a significant reduction in total nitrogen in plant tissues, and the accumulation of phosphorus and potassium. The addition of wheat straw and manure increased worm reproductive performance and coprolite output. Conclusions. The possibility of obtaining plant crop and earthworm biomass in an artificial ecosystem with various straw/ manure ratios in a peat substrate is shown. Funding. The work was carried out within the State Assignment of the Siberian Federal Scientific Center of Agrobiotechnologies of the Russian Academy of Sciences FNUU-2021-0005.

Keywords

• eisenia fetida
• lactuca sativa
• organic wastes
• microcosm
• photosynthesis