engleski

Effects of biostimulants on yield and quality of soilless grown tomatoes

Soilless culture is well known sustainable and environmentally friendly growing system, especially when plants are grown in closed hydroponic system. During year round cycle, soilless grown plants are optimally supplied with water and nutrients, what should result with high and quality yield. However, other abiotic and biotic factors also affect plants growth and development, and their interaction may cause stress conditions that could negatively reflect on plants. In recent years, biostimulants are applied before or during the stress conditions in order to enhance stress tolerance of plants and their yield, and to maintain a satisfactory quality. During the winter-spring period of 2016 the research with the aim to determine the effects of biostimulants on rockwool grown tomatoes was conducted. The experiment was laid out according to the randomized complete block design with three replications in heated greenhouse. Four tomato cultivars (Belle, Clarabella, Ladoga and Fizuma) were treated with biostimulants Polyamin, Bioplex and Halo Harpin at concentration of 0.2%. Untreated plants were used as a control. Plants were treated on four occasions, every two weeks between 22 February and 4 April. During the first two months of harvest period, from 18 April till 13 June, fruit weight and number, marketable yield and fruit quality (dry matter, total soluble solids, titratable acidity, vitamin C and total phenols) were determined. Although all tested cultivars are characterized as beefsteak, they differed significantly in all tested quantitative and qualitative parameters. Applied biostimulants had significant positive effect on fruit number, but did not significantly affect fruit weight and yield. Interactions of tested factors differed significantly. During the first two months of harvest an average between 11.4 and 18.5 fruits was harvested per plant. Fruit weight was between 170 and 211 g, while achieved marketable yield ranged from 2165 g (Ladoga ˟ Halo Harpin) to 3246 g/plant (Clarabella ˟ Polyamin). Tested cultivars and applied biostimulants, and also their interaction highly significant affected quality traits. Dry matter content was in range from 3.82 to 5.12%, while total soluble solids ranged between 3.03 and 3.63 °Brix. Determined values of titratable acidity were between 0.36 and 0.48. Vitamin C content varied from 11.96 to 21.87 mg/100 g fresh weight, and the highest values for all cultivars were recorded on control plants. Total phenols content (1.39 to 42.51 mg/100 g fresh weight) had the highest variability between tested qualitative traits. Due to the results it can be concluded that application of biostimulants had positive effects on yield of soilless grown tomatoes and some quality traits. On the other side, bioslimulants at the most cases lowered the content of vitamin C and phenols which have health promoting role in human diet, and which higher content in plant is a result of stress growing conditions.

Lycopersicon esculentum Mill., cultivar, biostimulants, marketable yield, total phenols

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