The effect of potassium nitrate on the status of fermentative and sucrose metabolizing pathways was studied in two maize (Zea mays L.) genotypes, viz., LM 5 (relatively susceptible to flooding) and I 167 (relatively tolerant to flooding) under water logging stress. The higher increase in pyruvate decarboxylase, alcohol dehydrogenase and aldehyde dehydrogenase activities in the hypoxic roots of I 167 seedlings over LM 5 showed the former’s efficient tolerance mechanism towards anaerobic conditions. Foliar application of KNO₃ reduced these enzymatic activities in the roots of both the genotypes. The shoots of I 167 seedlings also showed a parallel increase in alcohol dehydrogenase and pyruvate decarboxylase activities under water logging stress. These enzymatic activities, however, remained unaffected in shoots of water logged LM 5 seedlings. There was a higher decrease in acid and alkaline invertase activities in the hypoxic roots of I 167 seedlings. KNO₃ treatment led to higher acid invertase activity in roots of I 167 seedlings than those of LM 5. Sucrose synthase (synthesis) and sucrose phosphate synthase activities decreased, but sucrose synthase (breakdown) activity increased in the roots of both the genotypes, during water logging. KNO₃ increased sucrose synthesizing activities with a parallel increase in the sucrose content of the roots. Sucrose synthesis was comparatively unaffected in I 167 shoots under water logging stress while LM 5 shoots showed higher reduction in its sucrose synthase (synthesis) and sucrose phosphate synthase activities. It may thus be concluded that KNO₃ induced a network of reactions for improving water logging tolerance. The nitrate ions acted as an alternate electron acceptor and thus reduced the activities of fermentative enzymes. It promoted the funneling of sugars into the glycolytic pathway by inducing the activities of acid and alkaline invertases in the roots and shoots of maize genotypes. It also directed the hexoses towards biosynthetic pathway by increasing the activities of sucrose synthesizing enzymes.

中文翻译：

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硝酸钾的叶面处理可调节淹水胁迫下玉米基因型的发酵和蔗糖代谢途径。

研究了两种玉米（Zea mays L.）基因型对硝酸钾对发酵和蔗糖代谢途径状态的影响，即LM 5（相对易受水淹）和I 167（相对易受水淹）强调。I 167幼苗低氧根系中的丙酮酸脱羧酶，乙醇脱氢酶和醛脱氢酶活性比LM 5高。这表明前者对厌氧条件的有效耐受机制。叶面喷施KNO ₃降低了两种基因型根部的这些酶活性。在水淹胁迫下，I 167幼苗的芽也显示出乙醇脱氢酶和丙酮酸脱羧酶活性的平行增加。但是，这些酶活性在注水的LM 5幼苗的芽中不受影响。I 167幼苗低氧根中酸和碱性转化酶的活性下降较高。KNO ₃处理使I 167幼苗的根部酸转化酶活性高于LM 5。在此期间，两种基因型根部的蔗糖合酶（合成）和蔗糖磷酸合酶活性均降低，但蔗糖合酶（分解）活性提高。涝。硝酸钾₃增加了蔗糖的合成活性，同时增加了根部蔗糖的含量。在水淹胁迫下，I 167芽中蔗糖的合成相对不受影响，而LM 5芽显示其蔗糖合酶（合成）和蔗糖磷酸合酶活性的降低程度更高。因此可以得出结论，KNO ₃诱导了用于改善耐水性的反应网络。硝酸根离子充当替代电子受体，因此降低了发酵酶的活性。它通过诱导玉米基因型根和芽中的酸和碱性转化酶的活性来促进糖进入糖酵解途径。通过增加蔗糖合成酶的活性，它也将己糖导向生物合成途径。