Peculiarities of forming quality parameters of commercial products of cutting lettuce (<i>Lactuca sativa var. capitata L.</i>) depending on the method of cultivation

Purpose. To investigate features of commercial head quality formation in varieties of cutting lettuce (Lactuca sativa var. capitata L.) for different growing methods. To study the influence of growing methods for cutting lettuce plants on the weight of commercial heads, indices of yield and quality of freshly harvested products. Methods. Field study, laboratory testing and statistical evaluation. Results. The results of studying peculiarities of head formation in such cutting lettuce varieties as ‘Godar’ (control), ‘Smuhlianka’, ‘Olzhych’ and ‘Dyvohrai’ were shown. Based on the results of phenological observations, the duration of interstage periods of growth and development of cutting lettuce plants was determined for the different growing methods. The model of cutting lettuce of capitata variety for different growing methods was presented in terms of biochemical parameters (content of dry matter, vitamin C, nitrates, amount of sugars). The influence of growing methods for cutting lettuce plants on the commercial head weight, indices of yield and quality of freshly harvested products was studied. Obtained results confirmed that in early ripening varie­ti­es the heads were smaller (150 g) and not dense, in late ripening varieties they were large and dense, weight was 150–500 g. Freshly harvested commercial products of head lettuce in case of seedling cultivation was characterized by a slight increase in dry matter content by 0.15–0.29%. The corresponding pattern was observed for the total sugar content. Its amount was slightly higher: 1.3–1.9% in case of direct sowing and 1.6–1.9% – for seedlings cultivation. The content of ascorbic acid (vitamin C, mg/100 g) was the highest in the ‘Dyvohrai’ variety despite of the method of growing. The largest quantity of nitrates in lettuce heads was in the inner stem (480 mg/kg), while in the middle of the head it was reduced to 110 mg/kg. Conclusions. Freshly harvested heads of cutting lettuce were analyzed for the content of such basic biochemical indices as dry matter, vitamin C, protein, nitrates, amount of sugars. Biochemical characteristics of freshly harvested products of heading lettuce in case of direct sowing and non-seedling methods of growing were within the error being almost identical with minor deviations. According to the study results, a typical model of capitate lettuce variety was designed which will have practical application in qualification examination of plant varieties.