| Millet crops is a very bright light, high light saturation point, requires adequate illumination in the whole stages。 In the process of growth and development, millet often suffer from oligonucleotides as rainy weather, the influence of direct limits its photosynthetic capacity, not only the growth and development influenced by different degree, but also can reduce production。 This test was conducted in farming of Shanxi Agricultural University and crop chemical control laboratories in2012。 This experiment was conducted to study the effect of weak light on millet growing and research the millet yield and physiological characteristics of Zhangza5and Jingu21in different development stages under different shade density, using randomized block experiment design, set up three shade density, were30%(T1),60%(T2),85%(T3), millet crops grown in the field of natural light to control (CK), respectively in the jointing stage, heading stage and filling stage shade processing。 The influences of the main results were as follows:In the process of the shade millet height in a certain degree of rise in jointing stage, in late shade of Zhangza5plant height is lower than the control gradually, and in the valley of21until the end of shade as the shade density increases, the higher plant height; After the shade, the processing plant height is lower than controls。 Jointing stage shading significantly reduces the stem diameter, spike length and spike thick, but not affect Leaf length and width。 Heading and filling stage shade treatment on corn morphological indexes had no significant effect。Shading reduce millet plant biology yield, heading date delay.。The corn grain yield, ear weight and grain weight were significantly lower, especially in filling stage yield reduction is the largest, followed by the heading stage, jointing stage affect the minimum in shading condition。Millet leaf chlorophyll a, chlorophyll b and carotenoids were significantly lower, and chlorophyll a lower amplitude greater than chlorophyll b, resulting in lower chlorophyll a/b, this is good for blades absorb light scattering, and increase the absorptive capacity of weak light, to a certain extent make up for the shade to the inhibition of photosynthesis in shading condition。The millet leaf net photosynthetic rate, transpiration rate, stomatal conductance growing under natural light blade, intercellular CO2concentration were significantly increased, shows the effects of shading on millet photosynthetic rate is mainly determined by the stomatal limitation factors。 In the process of photosynthesis diurnal variation, found in natural millet crops grown in the photosynthetic lunch break phenomenon, shade but a certain degree of lift this lunch break phenomenon in shading condition。Along with the rising of the shade density, the potential activity of photochemical efficiency of millet leaf PS Ⅱ (Fv/Fo), the largest photochemical efficiency (Fv/Fm), actual photochemical efficiency (Φ PS Ⅱ) and light chemical quenching (qP) decreased significantly, the initial fluorescence (Fo), non photochemical quenching (NPQ) rise。 Under weak light conditions, millet leaf PS II reaction center the deactivation rate increased, the photochemical efficiency is reduced, to absorb more light energy in the form of heat dissipation are scattered out of the in vitro. Earing period, in the shade density condition, Fo due to the decreasing of chlorophyll content in down trends, Fv/Fm and Fv/Fo increases can be regarded as a millet leaf to the weak light environment of a self-adjusting mechanism, but along with the rising of the shade density, photosynthetic mechanism in reversible inactivation and D1protein degradation ratio increased, the electron transfer rate is reduced, which hold back the photochemical reaction of plants.The millet leaf soluble sugar and soluble protein content decreased significantly, and with the increase of shade density, lower amplitude。 In natural conditions or millet leaf nitrate reductase activity, has the high nitrogen assimilation capacity, nitrate reductase activity decreased significantly under the condition of shade, but no significant difference between30%and60%shade processing in shading condition。In the different shade stages, leaf SOD, POD activity and MDA content affect different, shading can induce the SOD, POD activity decreased, membrane lipid peroxide level increased, MDA content increased。 Heading stage in the process of the shade, millet plants showed certain self-adjustment ability, low shade density conditions, the activities of SOD, POD, MDA content decreased。... |
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