Effects of nitrogen deficiency on photosynthetic traits of maize hybrids released in different years
Effects of nitrogen deficiency on photosynthetic traits of maize hybrids released in different years
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DOI：
10.1093/aob/mci244
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发表时间：
2005-10-01
期刊：
影响因子：
4.2
通讯作者：
Li, YH
中科院分区：
文献类型：
--
作者：
Ding, L;Wang, KJ;Li, YH
背景与目的即使在降低施氮量的情况下，新玉米(Zea Mays)杂交种的表现也优于旧玉米杂交种。了解新、老杂交种在缺氮条件下表现差异的机理，可以为选育缺氮高产玉米品种，减少氮肥对环境的污染提供途径。方法通过田间试验，研究了近50年来育成的6个玉米杂交种的籽粒重、株重、收获指数、叶面积和光合作用性状，比较了它们的耐性，并探讨了它们的生理机制。然而，所有杂交种的收获指数、开花前20d的光饱和光合作用速率(P-sat)、开花时的叶面积和植株重量与对照无显著差异。在所有杂交种中，缺氮植株开花后的干物质生产都显著低于对照植株，尤其是老杂交种，这主要是由于这一时期光合能力下降的速度不同所致。老杂交种的P-sat较低不是由于气孔限制，而是气孔导度(g(S))和胞间CO2浓度(C-i)在杂交种之间没有显著差异。氮素缺乏促进了花后衰老，表现为花后叶绿素和可溶性蛋白质含量下降，早育杂交种比晚育杂交种表现得更为明显。缺氮显著降低老杂交种的磷酸烯醇式丙酮酸羧化酶(PEPCase)活性，仅在老杂交种和后期影响PSII光化学(Fv/Fm)的最大效率。结论与老杂交种(早熟杂交种)相比，新杂交种(晚熟杂交种)在缺氮条件下保持了较高的植株和籽粒重量，这是由于花后光合作用能力下降较慢，维持PEPCase活性、叶绿素和可溶性蛋白含量所致的非气孔限制较小。
Background and Aims New maize (Zea mays) hybrids outperformed old ones even at reduced N rates. Understanding the mechanisms of the differences in performance between newer and older hybrids under N deficiency could provide avenues for breeding maize cultivars with large yield under N deficiency, and reduce environmental pollution caused by N fertilizers.Methods N deficiency effects on grain weight, plant weight, harvest index, leaf area and photosynthetic traits were studied in the field for six maize hybrids released during the past 50 years to compare their tolerance and to explore their physiological mechanisms.Key Results N deficiency decreased grain yield and plant weight in all hybrids, especially in the older hybrids. However, there was no significant difference in harvest index, rate of light-saturated photosynthesis (P-sat) 20 d before flowering, leaf area or plant weight at flowering between the N-deficient and control plants of all hybrids. Dry matter production after flowering of the N-deficient plants was significantly lower than that of the control plants in all hybrids, especially in the older hybrids, and was mostly due to differences in the rate of decrease in photosynthetic capacity during this stage. The lower P-sat of the older hybrids was not due to stomatal limitation, as there was no significant difference in stomatal conductance (g(s)) and intercellular CO2 concentration (C-i) between the hybrids. N deficiency accelerated senescence, i.e. decreased chlorophyll and soluble protein contents, after anthesis more for the earlier released hybrids than for the later ones. N deficiency decreased phosphoenolpyruvate carboxylase (PEPCase) activity significantly more in older hybrids than newer hybrids, and affected the maximal efficiency of PSII photochemistry (Fv/Fm) only in the old hybrids and at the late stage.Conclusions Compared with older (earlier released) hybrids, newer (later released) hybrids maintained greater plant and grain weight under N deficiency because their photosynthetic capacity decreased more slowly after anthesis, associated with smaller non-stomatal limitations due to maintenance of PEPCase activity, and chlorophyll and soluble protein content.