Effects Of Different Planting Densities And Modes On Developmental Characteristics Of Summer Maize Populations

The contradictions is become more prominent with the improvement of production conditions and levels of summer maize.To increase yield further more, production efficiency of population maize should be full expressed, making population produce more efficient transfer of photosynthetic products and trafer to the grain. So to build a good group and improve the quality and yield of summer maize is the key technology of ultra-high-yield. This project under the summer maize of North Henan irrigated production conditions, study the summer maize's population quality indicators of main super high-yielding varieties of in Henan, quality and yield of maize to take control of technical measures to build high-quality corn groups, to achieve high efficiency on large area. To take control technical measures of quality and build heigh yield of maize and achieve a large size to provide evidence on the high efficiency.This experiment is designed by split plot with three factors, effects of different planting densities and modes on developmental characteristics of summer maize populations were studied in two varieties (Zhengdan958 and Xundan20) under high yield condition in the technology company of Ping'an of Henan Province between 2008-2009. The results are as follows.1. Effects of different densities and planting modes on developmental characteristics of summer maize populations in two varieties.The ear area index (LAI), chlorophyll content of leaves, biomass of shoots, plant height and height of ear position of two varieties with the increase of density or increased stem diameter as the density increases. By Duncan multiple comparison method showed that the variety of Zhengdan958 and wide-narrow row planting method were significantly superior than Xundan20, and the best yield's density was 82,500 / hm². The results from the best yield and in the wide-narrow row planting mode and density of 82,500 / hm² condition, the LAI of Zhengdan958's silking stage was about 6.69, Xundan20 LAI was about 6.61; Zhengdan958 groups of dry matter accumulation was 31103-31860kg/hm², Xundan20 was 28154 kg/ hm²; plant height, height of ear position and stem diameter of Zhengdan958 were 272.04,143.67 and 2.59cm; Xundan20 were 284.57,161.303 and 2.55cm.2. Effects of different densities and planting modes on the source metabolism of the two summer maize varieties.Two varieties of chlorophyll content, photosynthetic rate (Pn), leaf sucrose phosphate synthase (SPS) activity, nitrate reductase (NR) activity, leaf glutamine synthetase (GS) activity and leaf soluble sugar content decreased with the increase of the density.By Duncan multiple comparison method showed that the variety of Zhengdan 958 and wide-narrow row planting method were significantly superior than Xundan 20, and the best yield's density was 82,500 / hm². In the wide-narrow row planting mode and density of 82,500 / hm² condition, the leaf chlorophyll content of Zhengdan958's silking stage is about 5.10mg / g, Pn is 55.20μmol/m².s, SPS activity of leaf was 40.90μg^-1h^-1, NR activity was 80.46μg^-1h^-1, GS activity was 1.96Amg^-1h^-1, soluble sugar content was 2.41%; the leaf chlorophyll content of Xundan20 was 4.89mg / g, Pn was 53.45μmol/m².s, SPS activity of leaf was 38.30μg^-1h^-1, NR activity was 76.83μg^-1h^-1, GS activity was 1.87Amg^-1h^-1, leaves soluble sugar content is 2.26%. The results indicated that the group structure was optimized, then affected the final output.3. Effects of different densities and planting modes on the sink metabolism of the two summer maize varieties.Sucrose synthase (SS) and grain sucrose phosphate synthase (SPS) activity of two varieties were decreased with the increasing density, and the both of SS and SPS's activity were reached the significant level in the density of 82,500 / hm². By Duncan multiple comparison method showed that the variety of Zhengdan958 and wide-narrow row planting mode were significantly superior than Xundan20, and the best yield's density was 82,500 / hm². The results from the best yield and in the wide-narrow row planting mode and density of 82,500 / hm² condition, The SS and SPS's activity of Zhengdan958 were about 188.15μg.g^-1h^-1, 197.21μg.g^-1h^-1 at silking stage, the SS and SPS's activity of Xundan20 were 176.82μg.g^-1h^-1, 188.36μg.g^-1h^-1.4. Effects of different densities and planting modes on grain filling and grain quality of summer maize in two varieties.The grain size, grain dry weight, grain filling rate and grain sucrose content, protein content and starch content of two varieties were decreased as the density increases, above of all were reached the significant level in the density of 82,500 / hm². By Duncan multiple comparison method showed that the variety of Zhengdan958 and wide-narrow row planting method were significantly superior than Xundan20, and the best yield's density was 82,500 / hm². In the wide-narrow row planting mode and density of 82,500 / hm² circumstances, The mature grain volume,grain dry weight,filling rate,sucrose content,protein content and starch content of Zhengdan958 were 29.63cm3/grain,327.67mg/grain,11.67mg.grain-1d-1,3.83%,9.60% and 71%.The same characters of Xundan20 were 28.39 cm3/grain,316.19 mg / grain,1.47 mg.grain-1d-1,3.32%,8.19% and 70.48% .5. Effects of different densities and planting modes on the resistance of the two varieties of summer maize.Leaves of two varieties of superoxide dismutase (SOD) and catalase (CAT) activity increased with planting density decreased, peroxidase (POD) activity and malondialdehyde (MDA) were decreased with the increase of planting density. By Duncan multiple comparison method showed that the variety of Zhengdan958 and wide-narrow row planting method were significantly superior than Xundan20, and the best yield's density was 82,500 / hm². In the wide-narrow row planting mode and density of 82,500 / hm² circumstances, the SOD,CAT,POD and MDA activity of Zhengdan958's silking stage were 684.07u / g,70.95 u / g,144.43 u / g and 12.56μmol / g. The same of above were 676.96,67.67 u / g,153.53 u / g,13.65μmol / g.6. Effects of different densities and planting modes on on the two varieties yield.The results showed that characteristics of ear, grain yield and harvesting index were significantly influenced by planting density and mode in two varieties. Two varieties of ear length, ear diameter, grain number, grain weight and economic coefficient decreased with the increase of the density; Bald long as the increase of the density growth; the seed rate increased as the density increases first and then decreased ; The yield of Zhengdan958 was the highest (14236.97 kg/ hm²) at a density of 90000 plants per hm² in wide-narrow row planting mode, while the yield of Xundan 20 was the highest (13333.51 kg/ hm²) at a density of 82500 plants per hm² in wide-narrow row planting mode.In a word, effects of different planting densities and modes on above characteristics of summer maize populations were studied in some degree, of which the density is 8.250 000 / hm² and wide-narrow planting mode will be beneficial to plant dry weight, leaf area index, plant height and ear height, so that the quality characteristics of summer maize groups significant improvement, and help to improve the photosynthetic rate and chlorophyll content to maintain a strong maize photosynthetic capacity; help to improve nitrate reductase, sucrose phosphate synthase activity and the activity of sucrose synthase, grain size, dry weight, grain filling rate and soluble sugar, sucrose, starch and protein content, so the capacity of summer maize's sink was increased for accumulation of carbohydrates, laid the foundation for the high yield. Density of 82,500 / hm² and wide-narrow planting mode had highered SOD,CAT and POD activity and lowered MDA content and was conducive to delayed leaf senescence; the density of 82,500 / hm² and wide-narrow planting mode enhanced the effect of higher grain weight of summer maize grain and maize yield .So the density 8.250 000 / hm² and narrow-wide row planting mode was recommended to improved the yield of summer maize in North of Henan.