Co-Authors:
Bar-Yosef, B., Agricultural Research Organization, Bet Dagan 50250, Israel
Kritzman, G., Agricultural Research Organization, Bet Dagan 50250, Israel
Levkovich, I., Agricultural Research Organization, Bet Dagan 50250, Israel
Klaering, P., Institute of Vegetables and Ornamental Crops, Grossbeeren, Germany
Abstract:
Crop N nutrition has a major impact on plant susceptibility to various root path-ogens. The objective of this work was to investigate the effect of N concentration and NH4:NO3 ratio in a closed-loop irrigation system, on cucumber (Cucumis sativus L.) mortality caused by pythium and fusarium crown rot. Pythium aphanidermatum-inoculated cucumber was used as a test crop. Treatments included four NH4:NO3:urea ratios with the same total N concentration (9 ± 1 mM), and four N concentrations at constant NH4:NO3 ratio (30:70) in the fill solution. The threshold EC for solution discharge was 3.5 dS/m. Three days after planting the recycled solution in all treatments was inoculated with Pythium aphanidermatum. After 40 days of growth the mortality increased from 70 to 94% as the NH4:NO3 ratio was raised from 20:80 to 80:20. Repl-acing NH4 with urea reduced mortality to 22%. At NH 4:NO3 ratio of 30:70, increasing the total N concentration from 2 to 4-8, to 16 mM elevated the mortality after 40 days from 0 to 18-30, to 74%, respectively, and at 2 mM N no plant died until the end of the experiment. During the first 20-25 days after transplanting, the NH4 facilitated nitrite accumulation in the solution, which may have elevated the incidence of plants' infection. Later, increased NH4 concentration in the solution reduced the solution pH and the plant Ca concentration, two factors that were associated with enhanced mortality.
תפריט נגישות
ניגודיות עדינה
מונוכרום
הדגשת קישורים
חסימת אנימציה
פונט קריא
סגור
איפוס הגדרות נגישות
להורדת מודול נגישות חינם
