番石榴樹開花結果觀察

The Investigations on the Flowering and Fruiting Habits of Guava Tree

番石榴（Psidium guajava. Linn.）為熱帶及亞熱帶區域栽培廣泛之果樹，果實為食用普遍之果品，營養豐富，維他命ABCD含量均多，尤以維他命含量甚高，為各種果品中所少見者，故論果品價值，番石榴實有其不可忽視之地位，尤其獨特之點為此種果樹性質強健，不擇土質，故栽培容易管理簡單，而樹勢不大適於間作，且又生長迅速結果期早，長年結果，產量豐多，銷售容易，市價穩定，有此多種優點，故極為一般果農所歡迎，台灣全省各地，無不有其分佈，經濟栽培之收獲面積，年約七八百公頃，收量達三四百萬公斤，在本省果品生產量上，常居第六位，故於國民營養與農家經臍，關係頗鉅。

Guava, with its nutrious fruit and its ease of cultivation, has been a very popular fruit tree in recent yeas in Taiwan. An observation on the flowering and fruiting habits of the Guava tree was carried out from 1957 to 1958 in Taichung. The results are summarized as follows: 1.The Guava tree tears its fruits on the new shoots grown in the current year. Its flowers are pecfect flowers which shoot cut from the axi1 by pairs. Usually a flower will last for three days in lower temperatures, while in higher ttmperatures it will last only twenty-four hours. 2.The flowering time of the observed tree, from April to October, was 110 days. It blossomed most in April and least in September. In June and July, the flowers and fruits dropped numerously. The total percentage of fallen flowers was about 54%. The percentage of fallen fruits in respect to the total number th,t set was about 38%, and the number of harvested fruits was only 29% of the total flowers. 3.Since the Guava tree has a preccmirarce in termiral growth, it is the tendecy to bear fruit at the top of the tree. Threrfore, great attention must be paid in prunning in summer and winter to retard its overgrowth in order to increase the fruit production and to keep the. fruit bearing at pr oper places. 4.The optimum temperature for its flowering and fruiting was 22°C~28°C. Fruitage decreased when it was below 20°C, it also gradually decreased when it was over 28 °C. The higher the temperature above 28°C, the more the blossoms and fruits fell. 5.As to the we ather, clouly days were the best days for blossoming, sun shiny days were not so good, and rainy·days wera the worst. As to the relative humidity, the best condition was 70~80%. 6.The length and d!ameter of the Guava fruit was always in a parallel developme nt. No matter in what months the fruit set, they generally increase in size slowly until the last three or four weeks and then increased quickly. 7.The harvest started in July and lasted to March of the next year. August, December and March were the months of greatest yield. 8. Concerning the fruit developing time and·its quality, the ones which set in spring could be harvested in 105~115 days a nd were of good quality. The ones which grew in summer took only 100 days to ripen, but their quality was not so good. In autumn they took about 100 days to ripen. arid tneir quality was commorlly the best. Owing to the low temperatures in winter, the fr uits grew in that Season needed more days to ripen, and their quality wa s not veiy satisfactory.