Influence of nitrogen stress on nitrate accumulation and yield of lettuce varieties

Relevance. Many authors note the existence of significant genotypic differences in the assimilation of nitrogen and the accumulation of nitrates by lettuce, point to the additive-dominant nature of the inheritance of the trait. The aim of the work was to evaluate the response of lettuce of various cultivars to mineral nutrition stress created against a nitrogen-deficient background (N0) and with an increased dose of nitrogen (N200). Material and Methods. In a microfield experiment on well-cultivated soddy-podzolic soil, a collection of lettuce varieties belonging to the main cultivated variety types was studied. The varieties differed in geographical origin, early maturity and morphological characteristics. Results. Differences in yield between varieties against the background of N200 were 4.5 times, and against the background of N0 - 5.7 times. Against an increased background of nitrogen nutrition, the highest yield - 2.22-2.64 kg/m2 was formed by the following varieties: All the Year, Quedlinburger Dickkopf, Berlin Yellow, Great lakes. Against a nitrogen-deficient background, Azart and Odessa Kucheryavets varieties stood out in terms of yield, which absorbed soil nitrogen better than others. The content of nitrates in lettuce plants of different varieties varied more strongly when grown on the background of N200 and ranged from 10.7 to 13.6 times (on average over 2 years - 11,2 times), on the control of N0 - 33 times. Varieties accumulating maximum NO3 under conditions of excess nitrogen nutrition were revealed. Lettuce Romaine (Lactuca romana) - 353 mg/kg and White paris cus (198 mg/kg) had a low content of NO3. The period of the maximum increase in biomass also corresponded to the maximum decrease in NO3 in plants. Power function equations were calculated to estimate the rate of change in biomass and NO3 content. The results indicate that there may be some scope for NO3 reduction in lettuce through cultivar selection or breeding.