不同种子大小籽瓜品种叶片光合能力对源库调节的响应

The response of photosynthetic capacity of seed watermelon leaves of different seed sizes to the regulation of source-sink

为了探讨籽瓜叶片光合能力对源库调节的响应,以种子大小显著不同的3个籽瓜品种为材料,于开花坐果期通过整枝、摘叶、疏果将叶果比分别调整为10、20、30、40、50,并分别于幼果期、果实膨大期、果实成熟期测定叶片叶绿素含量及气体交换速率,收获后测定果实产量。结果表明,籽瓜功能叶叶绿素含量(SPAD值)、净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)随果实生育期演进逐渐降低,胞间CO2浓度(Ci)逐渐增大。3个供试品种间SPAD、Pn、Gs、Tr和Ci差异显著,大种子品种H26的气体交换参数(Pn、Gs、Ci、Ti)显著低于中等种子品种H14,H14显著低于小种子品种H3,但SPAD和Ci变化规律相反。叶片SPAD、Pn、Gs、Tr均值及其果实生育期降幅均随叶果比增大而显著降低(叶果比50除外),但叶片SPAD值和气体交换参数变化幅度无显著的品种间差异,说明一定范围内降低叶果比能提高叶片光合能力,但摘叶处理或叶果比过高均会加速叶绿素降解,诱发叶片衰老。3个品种单株果实产量随叶果比增大而提高,50(1.18 kg)>40(1.17 kg)和30(1.17 kg)>20(1.16 kg)>10(0.87 kg),H3单株果实产量(0.88 kg)显著低于H26(1.20 kg)和H14(1.25 kg)。以上结果表明,适宜范围的源库比能够提高籽瓜叶片光合能力,延缓叶片衰老,有利于籽瓜果实高产。

In order to explore the response of the photosynthetic capacity of source-sink adjustment with significantly different seed sizes,3 seed watermelon varieties as material,through the pruning and leaf and fruit thinning in flowering fruit period to adjust leaf-fruit ratio to 10,20,30,40,and 50,in young fruit period,expanding period,and mature period,the chlorophyll content,gas exchange rate,and post-harvest fruit production were determined.The results showed that the chlorophyll content(SPAD value),net photosynthetic rate(Pn),stomatal conductance(Gs),and transpiration rate(Tr)of functional leaves of seed watermelon gradually decreased with the evolution of fruit growth period while intercellular CO2(Ci)gradually increased.SPAD value,Pn,Gs,Tr,and Ci were significantly different among the three tested varieties.The gas exchange parameters of large seed variety H26 were significantly lower than that of medium seed variety H14 while H14 was significantly lower than that of small seed variety H3,but SPAD and Ci were opposite.The mean of leaf SPAD,Pn,Gs,and Tr in the fruit growth period drop with leaf-fruit ratio increases significantly reduced(except leaf-fruit ratio 50),but the leaf SPAD and gas exchange parameters change had no significant difference between varieties,showed a certain range to reduce leaf-fruit ratio than improved photosynthetic ability,but thinning leaf process or high leaf-fruit ratio accelerated chlorophyll degradation,induced leaf senescence.Fruit yield per plant of the three varieties increased with the increase in leaf to fruit ratio,50(1.18 kg)>40 and 30(1.17 kg)>20(1.16 kg)>10(0.87 kg),fruit yield per plant of H3(0.88 kg)was significantly lower than that of H26(1.20 kg)and H14(1.25 kg).The above results showed that the source/sink ratio in the appropriate range could improve the photosynthetic capacity of seed watermelon leaves,delay the senescence of leaves,and be beneficial to the high yield of seed watermelon.