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在新疆气候生态条件下,采用膜下滴灌植棉技术,设置不同滴灌水分处理,研究了不同滴灌量条件下棉花(Gossypium hirsutum)苞叶和叶片碳同化、光呼吸作用、光系统II(PSII)热耗散作用及其光破坏防御机制的差异,以揭示滴灌节水条件下棉花苞叶缓解光抑制的机理及与棉花抗旱特性的关系。结果表明:棉花开花后苞叶及叶片在高温强光下实际光化学效率(ΦPSII)显著降低,发生明显的光抑制现象,但苞叶的光抑制程度较叶片轻;与正常滴灌量处理相比,节水滴灌条件下棉花水分亏缺,叶片净光合速率(Pn)、ΦPSII、光呼吸(Pr)、光化学猝灭系数(qP)降低,非光化学猝灭系数(NPQ)升高,叶片光抑制程度加重,而苞叶Pn、ΦPSII、Pr、qP、NPQ变化不大,与正常滴灌量处理相比,光抑制程度无显著差异。苞叶光呼吸速率与光合速率的比值(Pr/Pn)显著高于叶片;滴灌节水条件下棉花适度水分亏缺对苞叶光呼吸及Pr/Pn无显著影响。高温强光下,棉花节水滴灌对叶片PSII量子产量的转化与分配影响显著,但对苞叶的影响不显著;苞叶非调节性能量耗散的量子产量(Y(NPQ))高于叶片,因此能有效地将PSII的过剩光能以热的形式耗散。综上所述,与叶片相比,苞叶对轻度水分亏缺不敏感,是棉花适应干旱逆境较强的器官,苞叶光呼吸和热耗散作用对光破坏防御具有重要意义。
Under the climatic and ecological conditions in Xinjiang, the techniques of film drip irrigation and cotton planting were used to set up different drip irrigation treatments. The effects of carbon dioxide assimilation, photorespiration, photosystem II (PSII) Heat dissipation and light damage defense mechanism differences in order to reveal the drip irrigation under the conditions of cotton husk alleviate the mechanism of photoinhibition and cotton drought resistance characteristics. The results showed that the actual photochemical efficiency (ΦPSII) of the husk and leaves decreased significantly under high temperature and high light, and the photoinhibition was obvious. However, the light inhibition of the husk leaves was lighter than that of the leaves. Compared with the normal drip irrigation, The water deficit, the net photosynthetic rate (Pn), ΦPSII, light respiration (Pr), photochemical quenching coefficient (qP), non-photochemical quenching coefficient (NPQ) However, there was no significant change in the contents of Pn, ΦPSII, Pr, qP and NPQ in the bracts. Compared with the normal drip irrigation, there was no significant difference in the degree of photoinhibition. The ratio of leaf photosynthesis rate to photosynthetic rate (Pr / Pn) in leaves was significantly higher than that in leaves. The moderate water deficit in cotton under drip irrigation and water saving had no significant effect on the photorespiration and Pr / Pn of husk. Under high temperature and high light, the effect of cotton water-saving drip irrigation on the transformation and distribution of quantum yield of PSII was significant, but the effect on the husk was not significant. The quantum yield (Y (NPQ) , So it is effective to dissipate excess light energy of PSII in the form of heat. In summary, compared with the leaves, the husk is not sensitive to mild water deficit, is a strong adaptation to drought stress of cotton organs, bract leaf light respiration and thermal dissipation of light damage to the defense is of great significance.