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为了明确不同氮素形态(铵硝配比)对芝麻苗期光合荧光特性的影响,探究适合芝麻生长的铵硝配比,采用营养液栽培方法研究了不同铵硝配比(10∶0、9∶1、3∶1、1∶1、1∶3、1∶9、0∶10)对芝麻品种中芝13(ZZ13)和漯12(L12)苗期光合特性、光合色素、叶绿素荧光参数的影响。结果表明,铵态氮比例过高显著抑制芝麻生长,铵硝配比为10∶0和9∶1时植株死亡,高比例铵态氮(铵硝配比3∶1)处理的芝麻幼苗地上部干质量显著低于其他处理;随着铵态氮比例降低,抑制作用减弱,并且适当配施硝态氮(铵硝配比1∶9)时2个芝麻品种地上部干质量达最大值,ZZ13和L12的叶绿素a、b含量及叶绿素总量分别在铵硝配比1∶9和0∶10时达到最高,而铵硝配比3∶1时上述光合色素含量大幅降低。铵硝配比1∶9时,ZZ13和L12的净光合速率(Pn)和蒸腾速率(Tr)均最大,而高比例铵态氮处理时Pn和Tr均显著降低,两者对铵态氮的响应较为明显。此外,与纯硝态氮处理相比,铵硝配比1∶9显著提高了ZZ13的光系统活性,表现为光系统Ⅱ最大量子效率(Fv/Fm)和实际光化学效率(ΦPSⅡ)显著增加,非光化学猝灭系数(q N)显著降低,但对L12光系统Ⅱ活性的提高不明显;而铵硝配比3∶1显著抑制了ZZ13和L12的光系统Ⅱ活性,表现为Fv/Fm、ΦPSⅡ和q P(光化学猝灭系数)值显著降低,Fo(基础荧光)和q N值显著增加。可见,铵硝配比1∶9最适合芝麻生长,尤其是对于ZZ13,其促进光合作用的主导因素是显著提高了光系统Ⅱ活性,而对芝麻叶片光合色素含量及组成比例的影响不显著;高比例铵态氮对芝麻叶片光合色素含量及组成比例、光系统Ⅱ活性、Pn和Tr都产生了不良影响,进而严重抑制芝麻的光合作用和生长。
In order to clarify the effects of different nitrogen forms (ammonium nitrate ratio) on the photosynthetic fluorescence characteristics of sesame seedlings at seedling stage, ammonium nitrate ratio suitable for sesame growth was explored. The effects of different ammonium nitrate ratios (10: 0, 1, 1: 1, 1: 3, 1: 9 and 0:10) on the photosynthetic characteristics, photosynthetic pigments and chlorophyll fluorescence parameters of sesame varieties ZZ13 and Lu12 influences. The results showed that the higher proportion of ammonium nitrogen significantly inhibited the growth of sesame, the ratio of ammonium nitrate was 10: 0 and 9: 1 plants died, the high proportion of ammonium nitrogen (ammonium nitrate ratio of 3: 1) The dry weight of the two sesame cultivars was significantly lower than that of other treatments. With the decrease of the ratio of ammonium nitrogen, the inhibitory effect was weakened. When the nitrate nitrogen (ammonium nitrate ratio of 1: 9) And chlorophyll a and chlorophyll a and chlorophyll a, b and chlorophyll a, b and c were respectively reached the highest at the ratio of ammonium to nitrate 1: 9 and 0:10, while the content of photosynthetic pigment decreased significantly when ammonium nitrate was 3:1. The net photosynthetic rate (Pn) and transpiration rate (Tr) of ZZ13 and L12 were the highest when ammonium ratio was 1: 9, while the Pn and Tr of ZZ13 and L12 were significantly decreased, The response is more obvious. In addition, ammonium nitrate ratio 1: 9 significantly increased the photosystem activity of ZZ13 compared with pure nitrate nitrogen treatment, showing a significant increase in maximum quantum efficiency (Fv / Fm) and actual photochemical efficiency (ΦPSII) The photochemical quenching coefficient (qN) of non-photochemical quenching (qN) decreased significantly, but the activity of L12 photoperiodⅡwas not obviously increased. The ammonium nitrate ratio 3:1 significantly inhibited the activity of photosystem Ⅱ of ZZ13 and L12, which showed Fv / Fm, ΦPSⅡ and q P (photochemical quenching coefficient) decreased significantly, Fo (basic fluorescence) and q N increased significantly. It can be seen that ammonium-nitrate ratio 1: 9 is most suitable for the growth of sesame. Especially for ZZ13, the dominant factor in promoting photosynthesis is that the activity of photosystem Ⅱ is significantly increased, while the content of photosynthetic pigment and the composition ratio of sesame leaves are insignificant. The high proportion of ammonium nitrogen had adverse effect on photosynthetic pigment content and composition ratio, photosystem Ⅱ activity, Pn and Tr in sesame leaves, and then seriously inhibited the photosynthesis and growth of sesame.