The objective of the study was to investigate the effect of different arsenic concentrations on some physiological parameters of bean (Phaseolus vulgaris L.) cultivars Plovdiv 10 and Prelom in the early growth phases. Seedlings, grown in sand with Hoagland-Arnon nutrient solution in a climatic box, were treated with 0, 2, 5 mg(As) dm -3 as Na 3 AsO 4 (pH 5.5). After 5 d of As treatment, the changes in leaf gas-exchange, water potential, chlorophyll and protein contents, peroxidase activity and lipid peroxidation in roots were recorded. Physiological analysis showed a minor negative effect of arsenic at concentration 2 mg(As) dm -3 , but at the higher dosage of 5 mg(As) dm -3 growth, leaf gasexchange, water potential, protein content and biomass accumulation were reduced in both cultivars. The peroxidase activity and lipid peroxidation increased considerably at 5 mg(As) dm -3 , which is a typical reaction of the plants to a presence of oxidative stress.

No abstract

No abstract

The aim of this study was to investigate the effect of organic fertilization on growth, several physiological parameters and yield of pepper plants (‛Buketen 50'). The field experiment was carried out at the experimental field of the Agroecological Centre of the Agricultural University of Plovdiv (Bulgaria), which is certified as an ecological farm. For the purpose of the research, the bio-fertilizer Lumbrical, produced by the Californian earthworm (Lumbricus rubellus), was used. Just before planting, two levels of the bio-fertilizer were applied 50 and 100 ml per plant. Thirty days after planting, a part of the plants were additionally fed with a solution of Lumbrical (200 ml per plant). During plant vegetation some biometrical indices characterizing plant growth were measured. The content of the plastid pigments and the leaf gas exchange were taken into account. The fertility of the pollen of the flowers was determined. The total amount of pigments in the dried and ground red pepper was analyzed.

The research was carried out on pepper of "Buketen 50" and "Gorogled 6" cultivars, intended for production of red pepper for grinding. Pepper plants were grown in a phytostatic chamber under controller conditions. The plants were cultivated as soil crops. For this purpose soil from the Agroecological centre at the Agricultural University of Plovdiv (holder of a certificate for ecological farm) was used. The experiment was carried out under the following scheme: 1. Control -soil (no organic fertilizer application); 2. Soil and organic-N fertilizer application. The indicated variants were formed during the pricking of the plants in phase 2-4 true leaf. For the purpose of the experiment organic-N fertilizer Emosan (authorized for use in organic farming) was attached. The fertilizer was applied at rate equivalent to 10.0 l da -1 . The results indicated that, applying organic-N fertilizer gave the vigorous plants expressed as plant height, leaves size as well as dry weight in both cultivars. The increase of dry biomass was mainly for the account of the increased mass of the above the ground organs.There was a positive effect of the fertilizer upon the functional activity of the photosynthetic apparatus /increased content of photosynthetic pigments, improved leaf gas exchange.