Studies on Physiology of Budbreak in 'Heng-Shan' Pear(Pyrus serotina R.) Trees

• Main Authors: Lu, Po-Sung, 盧柏松
• Other Authors: Yau-Shiang Yang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/38507763724659172411

碩士 === 國立中興大學 === 園藝學系 === 85 === Summary The buds of 'Heng-Shan' pear tree (Pyrus serotina R.) go into dormancy in September and remain in a state of deep dormancy from late November to early January. The degree of dormancy diminish from February and emergces in March in Taitung prefecture, Taiwan. The total soluble sugar content of shoots maintained high in late October, then decreased rapidly during deep dormancy period and thereafter increased again at budbreak time. The starch content increased from summer to autumn, and reached the maximum level in late October , then dropped significantly after February. Water content , protein nitrogen, and non- protein nitrogen concentrations of shoots decreased during the period of deep dormancy and increased when the dormancy came to an end. Chilling requirement of single bud cutting of 'Heng-Shan' pear reached 50% budbreak when shoots was exposed to 0 , 5 and 10℃ for 192 hours. However, in a potted plant test , 50% budbreak occurred when plants were chilled at 5℃ for 288 hours. The longer low temperature the shoots or pot plants was exposed, the shorter time was needed to break buds. Budbreak was enhanced when insufficiently chilled shoots or pot plants was treated with 1:4(fertilizer : water) or 1:8 calcium cyanamide solution. But the percentage of budbreak could not be able to reach 50% level if shoots or potted plant were not chilled. The percentage of budbreak was over 50% when exposed to low temperature(5 or 10℃) for 48 hours together with 1:4 calcium cyanamide solution. For buds or pot plants not receiving adequate chilling , the longer the low temperature for both shoots and pot plants, the better results could be obtained with calcium cyanamide solution was treated. The ratio of 1:4 calcium cyanamide was found to have more significant effects on budbreak. Field experiment was showed that induction of budbreak was least effective when applied in the middle of December if dormant 'Heng-Shan' pear trees were sprayed with calcium cyanamide solution(1:8) , however, better result could be expected if it was applied in the middle of January or February. The content of total soluble sugar increased rapidly and accumulated early in shoots in the middle February sampling. The optimal time to break dormancy was in late January in Taitung. Spraying solution filtering process, in general, did not affect much in this experiment.