Effect Of Nitrogen Management On Rice Population Quality And Transcriptomic Analysis Of Ear Organs

To study the effect of controlled-release nitrogen fertilizer on rice population quality, yield and nitrogen use efficiency, the experiment took place at rice original seed farm of Huainan City in Anhui province during 2012-2013. Conventional japonica rice ANW-1 and WD-68 were used as material, we set different nitrogen management models to study the impact of different nitrogen management on rice yield components, dry matter accumulation, nutrient absorption law, nitrogen absorption use efficiency and the differences of transcriptome in rice panicle under high/low nitrogen. The main results are as follows:1、The treatment of all controlled-release fertilizer was used as basal fertilizer and controlled-release fertilizer for basal fertilizer:chemical fertilizer for panicle fertilizer is 6:4 are superior to other modes of fertilization, dramatically increase yield and compared with other treatments, the differences of yield also significantly; The treatment of chemical fertilizer for basal fertilizer:chemical fertilizer for panicle fertilizer is 6:4 and controlled-release fertilizer for basal fertilizer:controlled-release fertilizer for panicle fertilizer is 6:4 have less effect to increase yield; The yield of ck is the lowest. Through the regression analysis of yield components, we found that effective panicles and thousand grain weight were the largest contribution to the yield components of conventional japonica rice. Dry matter accumulation of booting stage had the maximum correlation with yield (0.5502 and 0.2251, respectively), but were not significant; Dry matter accumulation of jointing stage had the minimum correlation with yield(0.9337 and 0.9386, respectively). These results suggest that topdressing panicle fertilizer in the booting stage on dry matter accumulation and yield formation of rice played a decisive role.2、Leaf nitrogen content of the two rice varieties showed a decrease trend after the first increase with the growth period and both reached the maximum at booting stage; but to the mature period, its reached the minimum values and occurred differences among the treatments. Nitrogen content in stems and sheaths also showed a trend of first increased and then decreased. Its indicated that different fertilization methods have no effect on conventional rice leaf nitrogen output period and the accumulation of nitrogen content in this time period. Accumulation of nitrogen content is gradually reduced to maturity, at that time treatment 2 is the lowest (1.48%), the difference nitrogen output periods of stem and sheath along with the different fertilization patterns as well as its nitrogen content, and there are also differences between different varieties. Nitrogen uptake and utilization efficiency showed that the fertilization methods of controlled-release fertilizer applied by installments and controlled-release fertilizer plus chemical fertilizer were help to improve their utilization; and fertilization methods of the highest agronomic nitrogen use efficiency is that all controlled-release fertilizer was used as basal fertilizer. Nitrogen physiological efficiency and nitrogen partial productivity are consistent with the yield, and the former was influenced greatly by fertilization methods, while the latter was less affected.3、The rice floral organs (Japonica) under the high nitrogen and low nitrogen treatment were transcriptome sequenced by the application of Illumina/Solexa sequencing platform. By quality evaluation, including inserting pieces inspection, comparing statistical analysis, cDNA fragments random experiment test and genetic coverage statistics, it indicated that the quality of Solexa sequencing was well to satisfy the demands of subsequent information data analysis. A total of 4309 differentially expressed genes (DEGs) were identified based on the comparison of high/low nitrogen library with Q-value≤ 0.01 and | Log2 (A/B) |>1 as screening criteria. Additionally, GO and Pathway analysis were performed for these DEGs and the result shown that DEGs had COG classification and that could be divided into 46 classes; A total of 62 significantly enriched GO terms were obtained by hypergeometric test. DEGs were shown to involve in 117 metabolic pathways, and fifteen of them were significantly enriched based the criteria of Q-value≤ 0.05, and nitrate reductase (LOC_Os02g53130, LOC_Os08g36480) involved in nitrogen metabolism pathway and β-glucosidase (LOC_Os03g20710, LOC_Os12g23170) involved in starch and sucrose metabolism pathway of rice young panicles nearly 10 times up-regulated expression under high nitrogen than that under low nitrogen; the β-glucosidase and hydrolase in starch and sucrose metabolism pathway were GO terms and that enriched significantly. This shows the absorption and utilization of nitrogen in rice plants could be regulated by LOC_Os03g20710, LOC_Os11g19210 and LOC_Os01g12020 genes.