Studies on Preventing the Tips of the Green Asparagus Spears
J. W. Chen and C. C. Cheng
The tops of green asparagus spears tend to loose more bracts during the high temperature period (above 30℃) from June to September in Taiwan. Previous reports have stated that many factors such as variety, climate, fertilization, soil moisture content, etc. all affect the size and tightness of bracts of spears. This experiment attempts to measure the suitable methods in fertilizer application and irrigation for decreasing the number of open-head spears and increasing the spear size for processing use. The results are summarized as follows:
1.Among four irrigation intervals: 5,8,10 and 15 days, it is found that 5 or 8 days interval plus straw mulching on the surface of designed plots maintained soil moisture content within 14~20%, and produced bigger and less open-head spears.
Applying nitrogenous fertilizer 60, 120, 180 kg per 0.1 ha per year found that the 180 kg one produced more open-head spears than the low fertilizer applications. Also it is found that nitrogenous fertilizer 60 kg per 0.1 ha would be enough to produce the maximum yield of green asparagus spears.