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How many acres of asparagus are planted on Chongming Island in Shanghai?
About 500 mu of asparagus is planted on Chongming Island in Shanghai. There are mainly two villages, Yangbin Village and Tongxin Village, along the port town.

Asparagus has a strong adaptability to temperature, which is both cold-resistant and heat-resistant, and can be cultivated from sub-cold zone to subtropical zone. But it is most suitable for temperate cultivation with distinct seasons and pleasant climate. In the alpine region, when the temperature is -33℃ and the thickness of frozen soil reaches 1 m, it can still safely overwinter, and the yield is low, but the quality is good. The initial germination temperature of asparagus seeds is 5℃, and the optimum temperature is 25 ~ 30℃. When it is higher than 30℃, the germination rate and germination potential decrease obviously. Breeding with seeds can grow continuously for more than 10 years. In winter, the aboveground parts wither in cold areas, and rhizomes and fleshy roots enter dormancy to overwinter; In warm areas in winter, the dormancy period is not obvious.

The dormancy period is extremely resistant to low temperature. When the ground temperature rises above 5℃ in spring, the scale buds begin to sprout; The tender stems begin to elongate above 10℃; 15 ~17℃ is the most suitable for bud formation; Above 25℃, the buds are thin, the scales are scattered and the tissues are aging; At 30℃, the bud elongation is the fastest; At 35 ~ 37℃, the growth of plants was inhibited, and even withered into summer sleep. The suitable temperature for photosynthesis of asparagus is15 ~ 20℃. When the temperature is too high, the photosynthetic intensity is greatly weakened, the respiration is enhanced, and the photosynthetic productivity is reduced.

Asparagus shoots new stems 2 ~ 3 times or more every year. Generally, the tender stems sprouted in spring are used for food, and their growth depends on the nutrient supply stored in the roots the year before. The growth of tender stems and the formation of yield are positively related to the number of mature stems and the lush degree of branches and leaves in the previous year. With the growth of plant age, the number of tender stems and yield increased year by year. With the continuous branching of rhizomes, the development of plant clusters tends to decline, the aboveground stems become smaller and smaller, and the yield and quality of tender stems gradually decline. Generally, 4 ~10 years after colonization is the productive period.