Of environmental factors affecting the secondary growth in garlic, the effects of irrigation, soil temperature, mulching, tunnel, nitrogen fertilization, and day length condition were tested in brief with observations on its developmental phase. The results obtained are summarized as follows;
1. According to the developmental phase, secondary growth were classified into slight, medium, severe one, and that occurred in bulbil. The slight one was related to the growth of protective leaf only, the severe one to the setting of secondary clove and the medium one to being in-between both of them, The slight secondary growth was not problematic in practical cultivation.
2. Plastic film mulch and tunnel promoted top growth and bulbing, respectively, but they were not the absolute conditions for the induction of secondary growth, but to be the factors accelerating the development of the induced secondry growth.
3. Secondary growth was not affected by the source of nitrogen (urea and ammonium sulfate), but the percentage occurance was increased with increment in the amount and frequency of nitrogen top-dressing.
4. All treatments of 8, 9, and 12 hours day length induced secondary growth, completely, and showed no significant differences among the treatments.
5. Considering the above results, secondary growth in differentiated clove of garlic seemed to be enhanced, when the above mentioned environmental factors including soil moisture and temperature were favourable for vegetative growth of garlic plants
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