冬春季氣溫波動對藍莓產量分佈與產期之影響

Abstract

藍莓(Vaccinium spp.)為原生於溫帶地區之落葉性果樹，秋、冬季環境日長與溫度誘導植株進入休眠。打破休眠則依賴低溫的累積，休眠解除後另需累積足量的積熱，方能使花芽開花並進入果實發育階段。臺北位處於亞熱帶地區，冬季低溫不足與春季氣溫波動大，對果實產期具有明顯影響。因此本研究分析自2018年9 月至2022 年7 月之氣溫資料，並利用低溫單位模型(chill units model)以及透過不同基礎溫度計算積熱(heat units)，觀察南方高叢藍莓(Vaccinium hybrid)、兔眼藍莓(Vaccinium virgatum)品種以及NTU兔眼藍莓品系產期的變化。2018/19 年低溫累積量為4 個年份中最少，2019/20 年與2020/21 年累積量相近並高於2018/19 年，而2021/22 年累積量為4 個生產期中最高的一期。積熱則以4 個基礎溫度進行計算，分別設定為0 °C、5 °C、10 °C、15 °C。以15 °C 的標準計算下，全期累積積熱以2021 年最高為42151.6 °Ch，其次為2020 年41306.4 °Ch 與 2019 年39763 °Ch，而2022 年最低為37210 °Ch。結果顯示，南高叢藍莓在低溫累積最少與最多的兩個年份，產期開始日明顯延後，需較高積熱量產期才開始，而兔眼藍莓與NTU 兔眼品系則是在低溫累積最多的年份產期明顯延後，在2021/22 年產期開始前累積最多。南高叢藍莓在低溫累積量最低及最高的年份，產期集中，總產期明顯縮短，產期開始至結束累積之積熱最少，兔眼藍莓與NTU藍莓總產期與低溫累積累較無關。而不同品種間產量達總產量50%之日期區間，在不同生產期間並無明顯的變化趨勢。整體上，南高叢藍莓產期較容易受氣溫變化所影響，而兔眼藍莓與NTU藍莓受影響程度不如南高叢藍莓明顯。

Blueberry (Vaccinium spp.) is a deciduous fruit tree native to temperate regions.In autumn and winter, environmental daylength and temperature induces dormancy.To break the dormancy, accumulation of chilling temperature is necessary. Once the dormancy is released, accumulation of enough heat is required for bloom and fruit development. Taipei is in the subtropical region, insufficient chilling temperature in winter and great temperature fluctuations in spring have a significant impact on the harvesting date and harvest windows. This study analyzed the temperature data from September 2018 to July 2022, using chill unit (CU) models and calculates heat units (°Ch) through different base temperatures to evaluate the response of several southern highbush blueberry (Vaccinium hybrid), rabbiteye blueberry (Vaccinium virgatum) varieties and NTU rabbiteye blueberry lines. Among the four years, accumulated chilling units in 2018/19 was the least; CU of 2019/20 was similar to that of 2020/21 and was higher than 2018/19, while CU of 2021/22 was the highest. The accumulated heat was calculated based on four base temperatures, which were set at 0 °C, 5 °C, 10 °C, and 15 °C. Calculated on the basis of 15 °C, 2021 had the highest accumulated heat at 42151.6 °Ch, followed by 41306.4 °Ch in 2020 and 39763 °Ch in 2019, and the lowest in 2022 was 37210 °Ch. The results showed that in the year with either less or high accumulated CU, the initial harvesting date of southern highbush blueberry significantly delayed, and the accumulated heat untils prior the initial harvesting date was higher. The initial harvesting date of rabbiteye blueberry and NTU rabbiteye blueberry were significantly delayed in 2021/22 with the highest chill unit accumulation and most of the varieties and lines were accumulated the most heat units in 2021/22. The harvest windows of southern highbush blueberry were significantly shortened in years with relatively high or low accumulated chilling units and the accumulated heat units during the harvest window were less. However, the accumulative yield reaching 50% of total yield among different varieties had no obvious difference in different years. Overall, the harvest windows of southern highbush blueberry were more sensitive to temperature changes in winter and spring, while rabbiteye blueberry and NTU blueberry line were less affected.