| Ginkgo(Ginkgo biloba L.),as a unique relic plant in China,with high development and utilization value in leaves,fruits,and wood,and a large demand.It is widely planted in China.Ginkgo biloba mostly grows in temperate and subtropical regions,and is cultivated and distributed in the northernmost boundary of Shenyang.The annual average temperature is 7.3℃,with an absolute minimum temperature of-32.9℃.Therefore,Ginkgo biloba has a wide adaptability to temperature,but there is still no systematic understanding of its response mechanism to temperature changes under natural conditions.In this study,five regions with annual average temperatures of 9.8℃,14.4℃,16.3℃,18℃and 19.8℃ were selected.The growth,leaf anatomical structure,photosynthesis,metabolites,antioxidant enzymes and endogenous hormones of ginkgo seedlings grown in these five regions for a long time were systematically measured and analyzed.Combined with the performance of their offspring seedlings in the same location,the adaptive mechanism of male and female Ginkgo biloba to temperature changes in the field was studied.The main results are as follows:(1)The annual average temperature of 18℃ is most conducive to the phenotypic growth of Ginkgo biloba.An appropriate increase in temperature results in a significant increase in tree height and diameter at breast height,with maximum increases of 20.30% and 8.14%,respectively.The average tree height of male plants is 13.65% higher than that of female plants,and the coefficient of variation is 5.35%lower than that of female plants.It is less affected by temperature than female plants.(2)The annual average temperature of 18℃ is most conducive to the formation of leaf morphology in Ginkgo biloba.Low temperature is beneficial for leaf thickening and increased structural tightness,with maximum increases of 16.05% and14.48%,respectively.High temperature is beneficial for leaf enlargement,with an increase in stomatal density and structural porosity,with maximum increases of16.05%,21.33%,and 25.18%,respectively.The coefficient of variation of overall leaf structure indicators of female plants is smaller than that of male plants,and the TP with the greatest difference is 6.24% lower than that of male plants.(3)The annual average temperature of 18 ℃ is most conducive to photosynthesis and chlorophyll accumulation in ginkgo leaves.High temperature is beneficial for the increase of Ci,Pn,Gs,and E in leaves,with the highest increase of Gs reaching 39.59%.The maximum increase in chlorophyll content with temperature is 57.54%.The coefficient of variation of photosynthetic indicators in male plants is smaller than that in female plants,and the E with the greatest difference is 10.73%lower than that in female plants.(4)High temperature is conducive to the increase of SP,terpene lactone,and polypentenol content,with maximum increases of 54.88%,50.12%,and 40.57%,respectively.Low temperature is conducive to the increase of SS and flavonoid content,with maximum increases of 38.60% and 45.60%,respectively.16.3℃ is the most suitable for the accumulation of amino acid content,and both high and low temperatures produce inhibition.The coefficient of variation of metabolic product content in female plants is smaller than that in male plants,and the highest difference in polypentenol content is 13.60% lower than that in male plants.(5)A lower average annual temperature is beneficial for improving the activity of antioxidant enzymes,with the highest increase in SOD with the most significant change reaching 69.83%.The enzyme activity is significantly reduced when the temperature is too high.The antioxidant enzyme activity of female plants is more stable,and the coefficient of variation is smaller than that of male plants.The POD with the largest difference is 11.53% lower than that of male plants.(6)The content of IAA and GA3 is relatively high at 16.3℃-18℃,which is82.65% and 88.26% higher than the minimum content,respectively.Both high and low temperatures can inhibit their accumulation.The ZR content gradually decreases with increasing temperature,with a maximum decrease of 17.88%.The ABA content significantly increases at both high and low temperatures.The variation coefficients of IAA and ZR in male plants are smaller,while those of GA3 and ABA in female plants are smaller.(7)Seedlings from different sources exhibit different traits compared to large trees from their source regions,and they perform best under conditions that are most similar to the environment from their source regions.The adaptability of large trees to temperature is to some extent inherited from seedlings,and areas with rapid temperature increases can increase the adaptability of ginkgo populations through the introduction and cultivation of ginkgo in high-temperature areas.In summary,Ginkgo biloba has a strong adaptability to temperature.Under natural conditions,Ginkgo biloba can ensure normal growth of individuals by adjusting growth characteristics,leaf morphogenesis,photosynthetic strategies,metabolite content,antioxidant capacity,and endogenous hormone content.Ginkgo biloba can also inherit certain adaptability to future generations,improving the population’s adaptability to temperature changes. |
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