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对4年生“红地球”葡萄叶片进行为期1个月的4个梯度水分处理:L1(田间最大持水量(50±3)%)、L2(田间最大持水量(60±3)%)、L3(田间最大持水量(70±3)%)、L4(田间最大持水量(80±3)%),在8月测量各处理的植物水势、光合作用日变化、光响应、荧光以及叶绿素含量。结果表明:4个处理方式下Pn日变化均呈单峰曲线,趋势基本一致,8:00时Pn达到最高,之后下降,L1下降的原因是非气孔因素,L2~L4下降的原因主要是气孔因素。日变化Pn平均值按顺序分别为4.61、8.20、7.76、7.60CO2μmol·m-2·s-1,在P<0.05水平上L1显著低于另外3个处理。光响应的数据发现最大光合速率Pnmax则是(L2、L3)>L4>L1。通过比较4个处理Fv/Fm以及叶绿素含量,发现L1和L4的Pnmax降低的主要原因是叶绿素含量的降低,与光系统Ⅱ(PSⅡ)光化学效率无关,因为4个处理Fv/Fm没有显著差异(P<0.05)。因此适度的灌水对于“红地球”保持高Pn是必要的,过量或者不足的灌水都会导致Pn的下降。
The 4-year-old “Red Globe” grape leaves were subjected to 1 month of 4 gradient water treatments: L1 (field maximum water holding capacity 50 ± 3%), L2 (field maximum water holding capacity 60 ± 3%) , L3 (70 ± 3%) and L4 (80 ± 3%), respectively. The water potential, photosynthesis diurnal variation, photosynthesis, fluorescence and chlorophyll content. The results showed that the diurnal variation of Pn showed a unimodal curve and the trend was basically the same under the four treatments. The highest Pn reached at 8:00 and then decreased. The reason for the decrease of L1 was non-stomatal factor. The reason for the decrease of L2 ~ L4 was mainly stomatal factor . The average daily diurnal variation of Pn was 4.61,8.20,7.76,7.60CO2μmol · m-2 · s-1 in sequence, and L1 was significantly lower than the other three treatments at P <0.05 level. The photo-response data revealed that the maximum photosynthetic rate, Pnmax, is (L2, L3)> L4> L1. By comparing Fv / Fm and chlorophyll contents of four treatments, we found that the main reason for the decrease of Pnmax in L1 and L4 was the decrease of chlorophyll content, which was not related to the photochemical efficiency of PSⅡ because there was no significant difference in Fv / Fm P <0.05). Therefore, proper irrigation is necessary to maintain a high Pn for Red Earth. Excessive or insufficient irrigation will lead to a decrease in Pn.