Effect Of Planting Densities And Modes On Lodging Resistance Of Stem In Summer Maize

The conflict between the reduction of farmland area and increase of corn demand was more and more serious. We must take measures to increase maize unit area yield. It was showed that the stem lodging is one of the main reasons to limite the corn yield. So it is important for achieving the potential yield of corn and the super-high-yeild to research the rules of lodging resistance of summer maize under different varieties and various planting modes.This experiment was designed by split plot with three factors and 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 2010-2011. The main results are as follows.1. The stalk breaking and barren stem percentage of Zhengdan958 was smaller than that of Xundan20. The stalk breaking and barren stem percentage under wide-narrow-row was smaller than that under the same-row. With the increase of density, the stalk breaking and barren stem percentage increased.2. The height has significant differences among varieties and planting densities, and the differences among the planting modes were not notable. The stalk height of Xundan20 is higher than that of Zhengdan 958, the atalk was higher under wide-narrow-row was higher than that under the same-row condition. The stalk height increased with the increased densities. The ear position coefficient of Zhengdan 958 was lower than Xundan 20. The ear position coefficient under same-row was smaller than the wide-narrow-row. The ear position coefficient increased with the increased densities. The stem diameter coefficient gradually reduced with internodes from down to up. The stem diameter coefficient under same-row was larger than that under the wide-narrow-row..3. The stalk crushing strength of Zhengdan 958 showed significant differences on the second internode and position internode. But it in Xundan 20 showed significant differences on position internode. The stalk crushing strength of Zhendan 958 and Xundan 20 under wide-narrow-row was bigger than the same-row. The stalk crushing strength reduced with the increased densities, but with a rise of section decrease amplitude decreases.4. The dry matter accumulation of Zhengdan958 was higher than Xundan 20. The photosynthesis of Zhengdan 958 is strong, the lodging resistance ability of Zhendan 958 increased. The dry matter accumulation under wide-narrow-row was bigger than the same-row. The dry matter accumulation reduced with the increased densities.5. The SPS and SS content in the summer maize stems increased from jointing stage to great bell mouth stage, and reduced from great bell mouth stage to heading stage. The SPS and SS content reduced with the increased densities. The SPS and SS content of Xundan 20 were bigger than Zhengdan 958, The SPS and SS content in the summer maize stems under wide-narrow-row was bigger than the same-row.6. In the whole growth period, The soluble sugar content in the summer maize stems were highest in jointing stage, and reduced with growth period, were lowest in heading stage. The soluble sugar content has significant differences on the treatment. The soluble sugar content of Zhengdan 958 were bigger than Xundan 20. The soluble sugar content under wide-narrow-row was bigger than the same-row. The soluble sugar content reduced with the increased densities. The cellulose content has significant differences on different varieties and planting mode. The cellulose content of Zhengdan 95 were bigger than Xundan 20. The cellulose content under wide-narrow-row was bigger than the same-row. The cellulose content reduced with the increased densities.7. The SOD and POD content of Zhengdan 958 are more than Xundan 20. The SOD and POD content under wide-narrow-row was more than the same-row. The SOD and POD content increased with the increased densities. But the MDA content of Xundan 20 was more than Zhengdan 958, The MDA content under same-row was more than the wide-narrow-row. The MDA content increased with the increased densities.8. 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 Zhengdan 958 was the highest (12463.96 kg/ hm~2) at a density of 90000 plants per hm~2 in wide-narrow row planting mode, while the yield of Xundan 20 was the highest (11258.18 kg/ hm~2) at a density of 90000 plants per hm~2 in wide-narrow row planting mode.In a word, according to the stem lodging-resistance index under different densities, the suitable planting density of two varieties was different. The suitable density of Zhengdan 958 was 82500 plants per hm~2 under wide-narrow-row, The suitable density of Xundan 20 was 75000 plants per hm~2 under wide-narrow-row. In this density condition, it were beneficial to reduce stalk breaking percentage, barren stem percentage and ear position coefficient, improve stem diameter coefficient, stalk crushing strength, enhance lodging-resistance; accelerate the accumulation of dry matter for stalks, soluble sugar accumulation, and finally increase the yield..