Study On Characteristics Of Response To Silicon Combination With Ammonium And Nitrate In Silicon High-efficiency Rice

Rice is one of the most important grain crops in China, its total output accounts for1/2of the national total grain output. Nitrogen supply level and ratio of ammonium and nitrate affect rice growth and its yield. Maintaining rice yields steady and reducing nitrogen supply level has become an urgent problem.Silicon effect rice growth and nitrogen uptake and distribution in rice. In this experiment, hydroponic experiments were conducted using three rice varieties (including silicon efficient rice varieties2:Teyou998(tolerant to low silicon), Teyou248(no resistant to low silicon) and silicon insensitive rice Bollyoul5). Rice growth characteristics, physiological characteristics, silicon absorption dynamics characteristics at three ratios of ammonium and nitrate conditions were studied to elaborate silicon nutrition mechanism and lay the foundation of the reasonable application of nitrogen fertilizer and silicon fertilizer in rice. The main conclusions are shown as follows:Ammonium nitrate ratio and silicon levels have different effects on the growth of three rice varieties. Bo Ⅱ you15showed higher biomass at ammonium nitrate ratio of75:25, regardless of the silicon level used (14mg/L and56mg/L), the biomass was significantly increased at ammonium nitrate ratio of50:50. Teyou998exhibits no obvious response for ammonium nitrate levels and the ratio of silicon; Teyou248showed higher biomass at ammonium nitrate25:75and showed no significant response for silicon level.Ammonium and nitrate ratio and silicon supply levels showed different response in root morphology of three rice varieties. In the normal silicon supply conditions (56mg/L), Bo II you15and Teyou248’s total surface area and the total volume were elevated with nitrate increase. The average diameter of rice Teyou998was the biggest at ammonium nitrate ratio for75:25while total volume was the smallest at the ammonium nitrate ratio for50:50. In low silicon supply conditions (14mg/L) Teyou998root tip number in ammonium nitrate ratio was significantly least at the ammonium nitrate ratio for75:25. Bo II you15’s total root length, root surface area, root volume are higher than that of normal while Teyou998’s total root length, root surface area, root volume are lower than that of normal at low silicon supply levels. Bo Ⅱ you15’and Teyou998’s total surface area, root numbers were higher than the numbers of extra silicon supply levels at ammonium nitrate ratio is50:50. Teyou248’s and Bo Ⅱyou15’s total surface area, average diameter, total volume was less than that of normal level of silicon at ammonium nitrate ratio was25:75.Root activity shows a consistent rule at ammonium nitrate ratio and silicon levels on three rice varieties of silicon. No matter under what conditions the ratio of ammonium nitrate was, root activity levels of normal silicon-treatment were less than that of low silicon-treatment. There is no significant difference of root activity in three rice varieties.Ammonium and nitrate ratio and silicon supply levels have different influence on the silicon chlorophyll contents of rice varieties. Chlorophyll content of BoⅡyou15is highest at normal silicon supply levels at ammonium and nitrate was75:25. No significant difference was found among other treatments; chlorophyll content of Teyou248decreased with increasing silicon supply levels at ammonium nitrate as75:25,25:75. It showed opposite rule at ammonium nitrate as50:50. Chlorophyll content of Teyou998in low silicon supply level was higher than that of in normal silicon supply level regardless of ammonium to nitrate ratio. The effect of the ratios of ammonium and nitrate on chlorophyll content was not significant in low silicon supply level. The chlorophyll content of Teyou998at ammonium to nitrate ratio of25:75was significantly lower than that of at ammonium to nitrate ratio of75:25.The ratio of ammonium nitrate and silicon, silicon nitride affect silicon nutrient absorption in three rice varieties. Silicon and nitrogen affects each other, this effect is more pronounced in the aerial parts. Teyou998can guarantee higher silicon content in aboveground part at low silicon content in roots and under conditions of low silicon content, and the silicon content in root was at a relatively low level in the silicon supply condition. The silicon content in root of Teyou248has a huge varies between the two silicon level, reached41%-92%, and the change was more obviously at ammonium nitrate ratio75:25; silicon content in aboveground part of three rice varieties were significantly different between the two silicon supply levels.There was a significant negative correlation between the three rice varieties on the part of the silicon content and total N content, there was no significant correlation between the roots of the silicon content and nitrogen; silicon content of the three rice varieties of aboveground and nitrate content were significant positive correlated, but root silicon content and nitrate nitrogen content also did not show significant difference.Silicon uptake kinetic characteristics of all treatments with three ratios of ammonium and nitrate fit the en2yme kinetic model of Michaelis-Menten, and the changes of kinetic parameters are different for three different silicon-efficiency rice. Mapping and Lineweaver-Burke (LB) had high veracity with1%significant level compared to data processing based on the values of R2; Effect of carrier quantity had no significant difference through three ratios of ammonium and nitrate, but Km or silicon affinity got1%significant level; Teyou248had higher silicon uptake rate only at50:50ammonium to nitrate in our experimental condition; Teyou998had higher silicon affinity at the same condition and that may be made difference in silicon efficiency by genetic background.Overall, the ratio of ammonium nitrate affects the absorption and distribution of rice silicon; silicon affects rice uptake and distribution of nitrogen in the root activity and chlorophyll content, silicon efficient rice roots can guarantee higher silicon content at aboveground silicon content at a lower level silicon conditions.