| Reed residue substrate is a new horticultural substrate made from the paper-mill's solid wastes by composting. Now, this new substrate is extended as peat alternative substrate hi East China with a 2,500-m3 monthly output. But there are still a lot of problems to be solved by research. Such as unstable products quality, existence of phytotoxic substance and imperfect physical properties. In the past, the applied research was concentrated on the cultivation of vegetable crops, lack on the ornamental plants and transplant production. In this thesis, we aim at solving above problems, to probe into the reason of obstacles of growth in reed residue substrate cultivation; to find out the rules of physical properties and improvement measures; to optimize the formulas for plug seedling production, cuttage, and tissue cultured plantlet transplant; to discuss the cultivation basics of reed residue substrate, tomato and gerbera as the samples.As the grower feed back that some reed residue substrates inhibit plant growth because of in-completed composting, we verified the problem by Pak Choi cultivation on reed residue substrates with different composting time, and hydroponics test by substrate extract on the tomato and capsicum seedlings. Results showed that insufficient composting reed residue substrates had inhibited the growth of Pak Choi seriously, in root rotting and leaf etiolating. But there were no similar phenomena in the hydroponics test. Results in the germination tests of several vegetable seeds showed that germination index of lettuce and tomato seeds were significantly inhibited by the insufficient substrate water extract. Total phenolic acids content decreased with composting time, especially after 3 months composting, it was consistent with the results of hydroponics test and germination test. So, the phenolic acids were supposed to be the important reasons of growth obstacles in cultivation. But GC-MS should be used in order to identify the dominant phenolic acids. Results of germination test indicated that lettuce germination test could be used as the inspection of substrate maturity.The total porosity and air space of reed residue substrate were 85%-90% and 40% respectively. The water-absorbing and water-holding capacity was low. Especially when it was used as container media, water leaked through the large porosity and around the container wall. The water-absorbing and water-holding capacity was improved after longer period composting as the wax content in the substrate decreased hi the composting process.To improve the physical properties of reed residue substrate, the change rules of bulk density, porosity and water-holding capacity were studied in detail. In general, the total volume shrank 10% after mixed with peat, perlite or vermiculite. The total porosity decreased, bulk density increased, especially after mixed with vermiculite. The resultsindicate that the reed residue substrate plus 10-25% vermiculite was the best formula, which had 75% total porosity, 55% water-holding porosity and 15-20% aeration porosity.The superabsorbent (stockosorb) was added to improve the water-holding capacity. Adding 4g/L polymer shows the best water-holding capacity in the range of 0 to 8 g/L adding proportion. In the same irrigation rate, adding superabsorbent effectively promoted plant growth. At water stress condition, superaborbent could slowly release the absorbed water to decrease the irrigation frequency and reduce the requirement of irrigation.In order to provide theoretical bases for plug seedling production, reed residue substrate was tested in tomato and capsicum plug production. The optimal mix, 75% reed residue substrate plus 25% vermiculite, was selected from the 10 formulas. This mix had 21% aeration porosity and 57% water-holding porosity, and excellent water-holding capacity. Seedling grown in this mix forms well developed root system and the roots intertwisted the mix as a stable lump. Adding vermiculite also could provide abundant K mineral nutrient for plants. But when the vermi... |
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