Einfluss der Wasserversorgung von Jungpflanzen angezogen in verschiedenen Substraten und Anzuchtsystemen auf biomorphologische und pflanzenphysiologische Merkmale bei Kopfsalat

Abstract

Wood fiber substrates perform well for lettuce seedlings production in speedling trays compared to standard commercially used press pots as well as growing media on peat base. Wood fibers contain a high air volume to allow higher levels of water tension without danger of water saturation in the substrate. For optimum growth they require a "high" matric potential. For cultivation of lettuce seedlings irrigation pulses at phi = -30 to -50 hPa are recommended in ebb and flood cultivation systems. This will provide good rooting and the least amount of proline, an indicator for plant stress. Accumulation of proline in lettuce seedlings could only be proved under conditions of visible stress symptoms. Not only water tension, but also the substrates in raising systems influence the free content of proline. At phi = -200 hPa proline in lettuce seedlings cultivated in a peat based press pots were ca. 40 % lower compare to seedlings in a wood fiber substrate in speedling trays. The difference in proline content between well-watered and stressed seedlings was smaller than with tomato transplants. Also, the correlation between proline content of lettuce seedlings and critical water tension for irrigation pulses was lower than with tomato transplant. The lettuce plants performed well after transplanting and no differences derived from seedling-treatments were recorded.