| dc.description.abstract | 夏季之高溫可顯著影響番茄之生產。水耕試驗結果顯示：高氣溫對番茄植株生育之影響遠甚於高水溫。夏季之高溫可造成番茄花粉、子房及柱頭之發育障礙，而影響到授粉受精過程之進行，以致著果率降低；又由於花粉管伸長受阻，使得受精率降低、種子數目減少、果實變小。此外，高溫也會影響番茄內生賀爾蒙的平衡，進而刺激果梗離層的形成以及影響光合產物的輸送。在同化養分之利用上，溫度對不耐熱品種葉片碳源向外輸送能力及果實中蔗糖合成澱粉之能力皆有較高之抑制作用，顯示高溫也可影響碳源之轉運與分配。高溫下之著果不良，乃是許多相關細部受損情況之綜合結果，而非單一因子所控制“因此，在耐熱性品種的篩選過程中，單由著果率之高低可迅速達到選拔之效果，但也可能錯失某些有益耐熱性之生理性狀。例如某些柱頭易凸出之品種其著果率雖低，卻具有活性高之花粉。在耐熱性品種育成方面，經過多年的雜交育種方法的培育，亞蔬中心已經育成較為耐熱之品系，但其夏作之產量仍遠低於適溫季節，顯示在耐熱之改良上還存留相當的空間。如果能就現有的優良品系之個別生理性狀加以強化（例如：提高花粉、子房之活性及果實對合成物之積儲力），可能有助於產量之更進一步提高。
High temperature is one of the important factors that impede tomato production in the summer season. Hydroponic experiments, with controlled solution temperatures of 18, 25, and 32¢XC, showed that the impact of root temperature is not as important as that of air temperature. High air temperature caused the abnormal development of reproductive organs, so that pollination and fertilization could not proceed properly, thus reducing fruit set rate. Poor pollen tube growth caused by high temperatures results in insufficient fertilization, affecting seed number and fruit size. Other physiological and biological characteristics are also influenced by high temperature, e.g. the balance of endogenous plant hormones in the floral organ and enzyme activities related with carbon export from the leaf or import of carbon to the developing fruits, etc. These reactions would affect sink strength of the ovary, and also affect utilization of carbon resources. Poor fruit yield of tomato in the summer season seems to be the result of a complex of factors, so in addition to fruit set rate, attention should also be directed to the broader genetic background concerning multiple morphological and biochemical processes. Some heat-tolerant breeding lines have been developed at AVRDC. The yield potential in the hot season, however, remains far below that of the cool season, so there is considerable opportunity for improvement. Conventionally, high fruit set rate and yield have been emphasized in the screening work for heat tolerance. These criteria offer only general consideration of the multiple factors related to heat tolerance. However, to enhance the level of heat tolerance and therefore higher production in the summer season, the improvement of specific characters such as pollen production, pollen viability, ovary sink strength efficiency of specific enzyme for photosynthate translocation, etc. must be addressed. | en_US |
