To address the problem of uneven moisture conditions of the rootballs of cabbage plug seedlings grown with conventional mist irrigation, we trialed the use of ebb and flow irrigation. We also attempted to improve the quality of the seedlings by adding NaCl to the culture solution. We obtained the following results.
1. With the ebb and flow irrigation system, 20% less working time was required than with conventional mist irrigation.
2. Ebb and flow irrigation promoted growth uniformity of seedlings and improved growth after transplanting.
3. Adding NaCl at a density of 0.3% to the culture solution encouraged greening of leaves and a decrease in the flat rate of plant appearance.
4. When NaCl was added early, seedling growth was greatly depressed.
5. Addition of NaCl 5 days before transplanting did not decrease yield.
6. Plug seedlings exposed to added NaCl acquired drought tolerance, as shown by both improvement of water-use efficiency and the results of electrolyte leakage testing after drought treatment.
7. Yield was higher with ebb and flow irrigation than with conventional mist irrigation.
Use of an ebb and flow irrigation system reduced labor costs, improved the uniformity of seedlings, and enhanced seedling growth after transplanting. Furthermore, adding NaCl at 0.3% 5 days before transplanting improved the adaptability of seedlings to the automatic transplanter and improved their drought tolerance with-out decreasing cabbage yield.
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