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在相同密度和栽培管理条件下,研究了豫杂35、中棉29和中棉19 3个品种生长中后期主茎叶片光合特性及衰老特点,以期探讨杂交棉高产形成的生理机制。结果表明:杂交棉豫杂35和中棉29与常规棉中棉19相比,打顶后其主茎倒3叶片的叶绿素含量高,随叶片衰老下降的慢;叶片生长前期气孔导度大,生长后期叶片PSⅡ实际光化学效率(ФPSⅡ)大,从而使其叶片光合速率高,且随叶片衰老下降慢,在后期仍表现较强的光合速率。此外,3个品种叶片的光合效率的日变化趋势均呈单峰曲线,总体趋势是杂交棉品种的峰值较中棉19的高且下降的慢;最大光化学效率(Fv/Fm)和ФPSⅡ的日变化均表现为倒抛物线型,但是豫杂35和中棉29的日变化曲线表现在中午前下降的慢,中午谷值浅,中午后恢复上升的快,表现对强光利用能力高。杂交棉所表现的上述高光效特性,为其多结铃,增铃重,获得高产奠定了光合生理基础。
Under the same density and cultivation management conditions, photosynthetic characteristics and senescence characteristics of main stem leaves of mid-and late-stage growth of Yuza 35, Zhongmian 29 and Zhongmian 19 were studied in order to explore the physiological mechanism of high-yielding hybrid cotton. The results showed that compared with the conventional cotton, the chlorophyll content of the three hybrids Yuza 35 and Zhongmian 29 was significantly lower than that of the normal cotton variety Zhongmian 19, with the decline of leaf senescence slowed down; The actual photochemical efficiency (ФPSⅡ) of PSⅡ in late growth stage was large, which led to high photosynthetic rate of leaves and slowed down with leaf senescence, and showed a stronger photosynthetic rate in later stage. In addition, the diurnal variation trend of photosynthetic efficiency of three cultivars showed a single peak curve. The general trend was that the peak of hybrid cotton varieties was higher and slower than that of CK19; the maximum photochemical efficiency (Fv / Fm) and ФPSⅡday However, the diurnal variation curve of Yuza 35 and Zhongmian 29 showed a slow decline before noon, a shallow noon valley and a fast rising after noon, showing a high ability to utilize glare. Hybrid cotton performance of the above-mentioned high light efficiency, for its multi-boll, boll weigher, access to high yield laid the photosynthetic basis.