Efekty nadmiaru azotu w żywieniu roślin ogórka (Cucumis sativus L.) rosnących w warunkach zróżnicowanej wilgotności podłoża [The effect of nitrogen excess in the feeding of cucumber plants (Cucumis sativus L. ) growing in conditions of various medium humiditv]

Abstract

Reaction of 21 days old cucumber plants on high nitrogen supply during the growth in the conditions of 70% and 30% fwc sand humidity was studied in the phytotron. Obtained results showed that nitrogen in concentration 24 mmol·dm^-3 (9 mmol higher than in Hoagland's medium) increased WSD, g_s, E, P_n, as well as content of some monosaccharides (ribose, glucose, fructose), disaccharides (saccharose, trehalase), proline and trigoneline but fresh mass of plants, leaf area and c, value in cucumber plants decreased„ However the effect of higher N dose on chlorophyll content in leaves and its fluorescence parameters (F_v/F_m, F_v'/F_m', ΦPSII, Q_p i Q_n) have not been noticed. Moreover, it has been shown that influence of supraoptimal N dose on the value of determined plant physiological activity index was considerably bigger in 30% than 70% sand humidity. The authors suggest that high concentration of nitrogen in medium evokes changes in metabolity of carbohydrates and nitrogen substances which lead to an osmoprotectans increase in plant cells. In this way plants are more resistant to an environmental stress effect.