Estimation of the Chilling Requirement and Development of a Low-chill Model for Local Peach Trees in Taiwan

臺灣農業試驗所緯度24°1’59”，海拔約85公尺，從1991~1998年間冬天每年平均低於12.9℃的低溫累積量為370小時。八年來本地桃樹與新選雜交後代需冷量的評估是藉著比較4個「關鍵栽培種」(亦即’Flordared’、’Premier’、’TropicSweet’和’TropicSnow’等)與待評估栽培種間的花期早晚，並收集八年間感應低溫起始日休眠完成期與盛花期之間每小時的平均溫度記錄，以便開發適合低需冷地區應用的臺灣新需冷模式。各關鍵栽培種的需冷量計算，即從感應低溫起始日至休眠完成或至盛花期所累積的低溫，經國外採用的三種不同低溫模式(即低於12.9℃的小時數、低需冷油桃模式與猶他低溫單位模式等三種)的測試結果，這些模式所累積的低溫皆偏低很多。經本所以「試誤法」從330萬餘組的測試組合中，所開發出來的臺灣需冷模式，用來測試4個關鍵栽培種的需冷量，結果顯示新模式較國外高需冷地區所開發的三個需冷模式表現更為精確。採用臺灣需冷模式對本地桃樹需冷量的評估為：’砂桃’210低溫單位(chill unit, CU)，’福州大桃’200CU，’雞慶桃’ 190CU，’苦桃’180 CU，’鶯歌桃’170CU，7612(‘Flordared’ x ‘Flordaprince’)150CU，7699(‘Premier’ x ‘Flordabelle’) 180CU。 Taiwan Agriculture Research Institute, latitude of 24° 1’59”, and altitude of85m, has an average annual chilling hours of 370 hours below 12.9℃. The chilling rquirements for local peach cultivars and new selections had been determined by the comparison of blooming dates with “4 key cultivars” (‘Flordared’, ‘Premier’, ‘TropicSweet’, and ‘TropicSnow’) for 8 years. The speech phenological data, including the hourly mean temperature records between the initial dates of chilling to rest completion dates and full blooming dates from 1991 to 1997, were collected for developing a new chill model for low chill regions (Taiwan chilling model). Chilling requirements for key cultivars were calculated from the initial dates of chilling to rest completion by 3 different models which were named the number of hours below 12.9℃, low-chilling nectarine model, and Utah chill-unit model. These models underestimated the accumulated chilling. The Taiwan chilling model developed by “try and error method” from more than 3.3 million combinations when tested with the “4 key cultivars” performed more accuartely than the other three chilling models developed in higher chill zones. Using the Taiwan chilling model the chilling requirement of peach genotypes were estimated as 210 CU for ‘Swa-taur’, 200 CU for ‘Fu-jou-dah-taur’, 190 CU for ‘Ji-ching-taur’, 180 CU for ‘Kuu-taur’, 170 CU for ‘In-ge-taur’, 150 CU for 7612 (‘Flordared’ x ‘Flordaprince’) and 180 CU for 7669 (‘Premier’ x ‘Flordabelle’)

Physiological Studies on Flowering and Fruiting of Mume Trees

在兩個果梅產品調查果梅開花、果實發育特性並記錄全年果實生長發育期間的溫度變心、調查梅不完全開花的發生頻率，’長藤’最高可達15.8％，少者如’桃形梅’僅有3.0％，發生率高低因品種而異。不完全花其雌蕊長度從0～0.6cm不等，正常花雌蕊之臨界長度約在0.61～0.8cm長的雌蕊發育逐漸趨向正常著果，正常雌蕊最長可達1.35cm。 由果梅三個不同栽培種連續三年產量的綜合變方分析結果得知，不同栽培種於不同年度的產量表現有極顯著的差異，即年度與栽培種間有交感效應存在。年度間產量的顯著差異，表示果梅大小年的現象很明顯。品種間產量的顯著差異，表示果梅產量潛能因品種與株齡而異。 梅開花前的樹體變化調查，其芽體大小與重量在生長季節中變化不大，至8月中下旬以後開始有明顯的變大與變重，至盛花期止。生長季節中梅帶葉枝條含碳水化物的變化趨勢不甚明顯，於10月樹體開始落葉休眠時達最高點，開花前一個月（11月）顯著地降至最低點，而含氮的變化亦以花前一個月（11月）降至最低點，然然再逐漸上升。休眠期間碳水化物與氮與含量減少的趨勢伴隨著芽體的變大與變重。 The blooming, fruit growth and development of mume were studied at two locations during different growth stage and the climatological data were recorded. The occurrence of imperfect flowers in mume varied in cultivars. ‘Chang-teng’ (長藤) which prone to imperfect flower formation had degenerated pistils at a rate as high as 15.8%, while ‘Taur-hsing-mei’ (桃形) had only 3%. The pistil length varied from 0 to 0.6 cm in degenerated flowers. The transitional pistil length for functional flowers was between 0.61 and 0.8 cm. Pistils longer than 0.8 cm developed to set fruit normally. The pistil of normal flower could reach 1.35 cm in length. The yields of 3 different cultivars of mume were investigated for 3 years. The results of combined ANOVA over 3 years indicated significant interaction between years and cultivars. It also indicated the phenomenon of no-year and off-year in fruit production. The significant yield difference among cultivars revealed that the yield potential depended on both the cultivars and age of the plant. During rowing season, the size and the weight of lateral buds of new shoot did not change until late Auguest. In the meantime, the total carbohydrates remaimed almost the same level. A peak occurred in October when buds started dormancy, and a significantly rapid decline followed in November, a month prior to blooming. The pattern of nitrogen change was similar to that of carbohydrates. The decreasing of these two compositional materials was accompanied with the increasing in bud size and bud weight during plant dormancy

Immediate Effects of Pollen in Fruit Trees

果樹花粉親對母本果實或子或是兩者皆會產生當代的立即效應，其影響範圍包括果實或種子的形狀、大小、品質、顏色、貯藏期限、種子休眠及成熟期早晚等，本文列舉一些果實直感（metaxenia）與種子直感（xenia）的實例，期望能引起果樹產業對選擇果園粉樹的重視，以達到提高產量或改進品種質的目的。 The pollen parents of fruit trees have direct action on the fruits and/or seeds. The immediate effect of pollen may affect the shape, size, quality, color, and duration of storage of fruits or seeds, seed dormancy or fruit ripening. Many cases of metaxenia and xenia in the fruit trees were discussed in this paper. It showed the merits of using pollinizer of fruit trees, since the quality or ripening time of fruit can be improved. It would be worthwhile to find a suitable pollen source for fruit production