Effect of Drip Irrigation, N-Fertigation and Cultivation Methods on the Yield and Quality of Carrot
In the years of 2004-2006 research on influence of surface and subsurface drip irrigation on yield and quality of carrot grown on ridges and on the flat ground was investigated. Irrigation was started at soil water potential of 30-40 kPa. Nitrogen fertilizers (100 kg.ha-1) were applied in two rates. The first rate was preplant applied, the second was used by fertigation. In the control treatment without irrigation, the second rate of nitrogen was applied by broadcasting. Surface and subsurface drip irrigation significantly increased the yield of carrot. In cultivation on ridges higher yield of the carrot was obtained when surface drip irrigation was applied as compare to subsurface method. Carrot cultivated on ridges produced significantly longer roots than cultivated on flat ground. Generally the surface and subsurface drip irrigation decreased dry matter content and total N content in carrot roots. Drip irrigation at both cultivation methods increased pH and decreased the salt concentration of the soil.
The Possibility to Use Selected Mixtures of Pgpr Bacteria in Tomato Cultivation
Mixtures of different plant growth-promoting rhizobacteria (PGPR) were used to control soil-borne pathogens of tomato plants. First, their effect was studied in mini-chamber tests against Rhizoctonia damping-off. The best strains and their mixtures were selected for the greenhouse and field experiments conducted in years 2006-2007. The seeds and then the roots of tomato transplants were inoculated with the suspensions of single bacterial strains or with their combinations. In the greenhouse experiments treated plants were grown in the potting medium infested with pathogenic Fusarium oxysporum f. sp. lycopersici, and the effect of bacteria on the population of Fusarium spp. in the rhizosphere was studied. In field experiments the plants were planted into natural infested soil. In both kind of the experiments (greenhouse and field) the impact of the inoculation on plant yield and diseases incidence was evaluated. Although, the results of the preliminary and mini-chamber tests were promising, and the bacteria B125, PT42, SZ141 and their mixtures significantly reduced damping-off of tomato seedlings, in greenhouse and field experiments, in most cases the bacterial treatments failed to improve yield and to protect the plants. Among tested bacterial inoculations only the mixture of the bacteria B125 and PT42 tended to affect positively the growth of the plants and to reduce their infection by soil-borne pathogens. However, bacterial inoculations significantly decreased the density of Fusarium spp. in the rhizosphere of tomato plants.
Effect of Cultivation Methods and Drip Irrigation on the Yield of Roots and the Quality of Chicons of Witloof Chicory
In the years 2005-2007, a study was carried out to investigate the effect of surface and subsurface drip irrigation on the yield of witloof chicory in flatground and ridge cultivation. Irrigation began at a soil water potential of 30-40 kPa. Irrigation was found to have a beneficial effect on the yield and quality of the roots of witloof chicory. The largest increase in yield was obtained in the first year, in which there was a drought during sprouting and scarcity of rainfall during vegetative growth. In flat-ground cultivation, and in the year with insufficient soil humidity in ridge cultivation, surface irrigation was more beneficial in comparison with subsurface irrigation because it created better conditions in terms of moisture levels, particularly for the germinating seeds. In the years with sufficient rainfall during germination and sprouting no significant differences were found in the yield of chicory roots between surface and subsurface irrigation.
Chicory plants were forced hydroponically in water using a standard nutrient solution. The roots obtained from irrigated plots, as well as those from flatground cultivation, produced significantly longer and tighter chicons. Over the three years of the study, internal browning of the stem, which is a physiological disorder lowering the quality of chicons, occurred only in 2005. It might have been caused by high temperatures during sprouting and high moisture deficiency in the soil during vegetative growth. The use of irrigation significantly reduced the incidence of this phenomenon, especially in flat-ground cultivation.
The Influence of pH of Nutrient Solution On Yield and Nutritional Status of Tomato Plants Grown in Soilless Culture System
The aim of the studies conducted in the years 2004-2006 was determination the influence of nutrient solution of different pH on the yield and nutritional status of tomato plants grown in soilless culture in organic and inert medium. Tomato plants were grown on slabs made of shredded rye straw and on slabs of peat and rockwool. The plants were fertilized with standard nutrient solution of different pH: 4.5, 5.0, 5.5, 6.0, 6.5. Nutrient solution pH and the kind of applied growing substrates were exerted significantly influence on the height of total and marketable yield of tomato cv. Blitz F1. Early yield was not depended on pH of nutrient solution and the kind of using substrates. The highest total and marketable yield was observed in tomato grown in rockwool slabs. For all the growing media, the highest yield of tomatoes was obtained after feeding the plants with the nutrient solution of pH 5.5. The kind of growing substrates and pH of nutrient solution were significantly differenced the nutritional status of tomato plants. Despite of considerable differentiation of means concentration of mineral nutrient in tomato leaves, the plant growth and development were proper. Concentration of mineral nutrients was comprised at the optimum range of nutritional status of tomato plants. The pH of nutrient solution at the range of 4.5-6.0 was not exerted significantly influence on nutritional status of tomato plants with nitrogen, potassium and magnesium. With the increase of the pH nutrient solution the average phosphorus, iron and manganese content was decreased. The higher concentration of nitrogen, calcium and magnesium was occurred in tomato plants cultivated in organic substrates than in rockwool. The phosphorus and manganese content was higher in the leaves of tomato plants grown in rockwool compared to those in the organic media. Tomato plants grown in the straw substrate contained lower concentrations of potassium and iron and more calcium in comparison to peat.
Effect of Nitration of Organic Materials on Nitrogen Availability and Yield of Tomato in Soilless Culture
In the cultivation of horticultural plants in greenhouses the most commonly used substrate is rockwool, while organic substrates are used in an unprocessed state. Cultivation in organic substrates, after they have been suitably processed, also makes it possible to obtain high yields at levels similar to those in rockwool cultures. Fibrous organic substrates, due to the wide C:N ratio, are characterized by high biological sorption towards nitrogen, causing N deficiency during the initial period of plant growth. In 2007-2009, a study was conducted, the aim of which was to determine the effect of nitration of fibrous organic substrates (sawdust, rye straw, flax shives) with nitric acid on nitrogen availability and the yields produced by tomato plants. The process of nitration of the organic substrates was carried out with the use of 10% HNO3. The appropriate pH of the substrates after the process of nitration was obtained by washing the substrates with water. As a result of nitration the levels of nitrogen fixed in lignin compounds and simpler polysaccharides increased to about 2%. Nitration of the organic substrates increased nitrogen availability to plants in the first five weeks of culture. Subsequently, the N-NO3 content in the nutrient solution collected from the nitrated substrates was at the same level as for the nonnitrated substrates. The yields produced by tomato plants depended on both the nature of the substrate and whether or not it had been nitrated with nitric acid. The most useful organic substrate for soilless culture, retaining good structure during the growing period, was the substrate of sawdust. The substrate of straw was found to undergo quick biodegradation, therefore its usefulness for soilless culture was low. The highest yield of tomato was obtained from the cultures on rockwool and on the nitrated sawdust substrate; the lowest yield was produced on the straw substrate.