Studies On Traits Correlating To Lodging Resistance Under The Different Fertilization Manner And Planting Density In Rice

In this study, 6 varieties or combinations of medium indica rice, widely used on the production, through the different treatments of the nitrogen, kalium, silicon fertilizer application and planting density, were studied on the relationship between rice stem morphological, physical and chemical traits and lodging resistance on 30 day after heading. Stem traits closely related to lodging resistance were defined. These stem traits were compared in the different treatments. The lodging resistance cultivation conditions, which benefited the optimization of plant height and stem internode traits, were sought. The results are summarized as below.1 The significant negative correlation was found between the rice plant height and stem-index. The stem basal first elongated internode length was significant positively correlated with lodging index, the second and third elongated internodes length was significant negatively correlated with lodging index; three elongated internodes diameter and elliptical cross-section area were negatively correlated with lodging index, but were significant positively correlated with stem-index, the correlation coefficient was over 0.833; three elongated internodes stem wall thickness and stem cross sectional area were significant negatively correlated with lodging index. Breaking-resistant force, breaking moment, section modulus and bending stress were significant negatively correlated with lodging index. Elongated internode dry weight per unit length was significant positively correlated with section modulus, breaking moment and internode moment, it was significant negatively correlated with lodging index, it was not obviously correlated with bending stress. Elongated internode usable carbohydrate(soluble sugar and starch) content was significant positively correlated with section modulus, breaking moment and internode moment, it was significant negatively correlated with lodging index2 Rice stem morphological, physical and chemical traits such as plant height, stem basal elongated internode length, diameter rough, stem wall thickness, breaking-resistant force, breaking moment, section modulus, bending stress, internode dry weight per unit length, soluble sugar content and starch content were closely correlated to the actual lodging resistance.3 Under the conditions of four nitrogen fertilizer, plant height was significant difference, the greater amount of nitrogen, the higher plant height; the amount of nitrogen affected very obviously stem basal three elongated internodes lenghth, low-nitrogen promoting, high nitrogen restraining; the amount of nitrogen affected stem basal three elongated internodes diameter and wall thickness in the different degrees, with the amount of nitrogen increasing, internode rongh and stem wall thickness increasing, but the amount of nitrogen was not better as more; stem basal first elongated internode dry weight was significant difference in different amount of nitrogen conditions, the more nitrogen fertilizer application, the less dry weight per unit reduction; basal internode soluble sugar content was high and starch content was mediun in high amount of nitrogen conditions; starch content was highest in on nitrogen fertilizer conditions; the amount of nitrogen affected obviously the section modulus and bending stress of stem basal elongated internode, the amount of composition of stem was most in the middle of nitrogen, low nitrogen enhanced the strength(bending stress) of stem.4 Silicon and kalium fertilizer application affected little plant height; silicon and kalium fertilizer application decreased the length of stem basal internode and increased diameter; silicon fertilizer was not conducive to stem wall thickening, kalium fertilizer was conducive to stem basal second elongated internode wall thickening; silicon and kalium fertilizer application increased stem basal three elongated internodes dry matter; silicon fertilizer was not conducive to raising the soluble sugar content in rice basal stem, was conducive to raising the starch content in stem basal second and third elongated internodes; kalium fertilizer was not conducive to raising the soluble sugar content, starch content and usable carbohydrate content in rice basal stem; silicon fertilizer enhanced the strength of stem, appropriate kalium fertilizer increased the amount of composition and the quality of stem.5 Three planting density affected stem basal three elongated internodes diameter, wall thickness and dry matter weight in the different degrees, sparse planting was conducive to increasing stem rough, wall thickness and basal internode dry matter; the soluble sugar and starch content of stem basal internodes was significant difference in the different planting density, dense planting enhanced the soluble sugar content of basal internodes, sparse planting enhanced the starch content of basal internodes; planting density affected obviously section modulus and no-obviously bending stress, sparse planting raised the amount of composition of stem.6 Lodging resistance cultivation conditions: under the conditions of middle soil fertility, the application of purity nitrogen 150 kg/hm², line and plant distance of 26.6cm×16.6cm cultivation conditions, plant height and stem traits had been optimized, which was conducive to stem the lodging resistance; SiO₂75kg/ hm² or K₂O 150kg/hm² enhanced the lodging resistance of stem.