Utilization Of Rice Research Articles

Effects of Astragalus sinicus combined with chemical fertilizer on nitrogen absorption and utilization of rice and nitrogen distribution and residue of Astragalus sinicus in rice-soil system.

Clarifying the pattern of nitrogen absorption and utilization of rice under the treatments of Astragalus sinicus combined with chemical fertilizer application and the pattern of absorption, utilization, distribution and residue of A. sinicus nitrogen in rice-soil system could provide basis to rational fertilization for rice planting area in southern Henan. In this study, undisturbed soil column simulation and isotope tracer technology of 15N were used to examine the differences of nitrogen uptake and utilization of rice, nitrogen nutrient balance of rice-soil system and nitrogen uptake, utilization, distribution and residue of A. sinicus nitrogen after mineralization and decomposition among seven treatments. The treatments involved 1) no fertilization (CK); 2) chemical fertilizer+22500 kg·hm-2 A. sinicus (FM1); 3) chemical fertilizer+30000 kg·hm-2 A. sinicus (FM2); 4) chemical fertilizer+37500 kg·hm-2 A. sinicus (FM3); 5) chemical fertilizer+22500 kg·hm-2 A. sinicus +lime (FM1+CaO); 6) chemical fertilizer+30000 kg·hm-2 A. sinicus lime (FM2+CaO); 7) chemical fertilizer+37500 kg·hm-2 A. sinicus +lime (FM3+CaO). Results showed that compared with CK, fertilization significantly increased nitrogen uptake of grain and rice stalks, apparent nitrogen loss, and nitrogen surplus. The grain nitrogen uptake, rice straw nitrogen uptake and nitrogen use efficiency of rice increased firstly and then decreased with the increasing A. sinicus application rates, while the apparent nitrogen loss and nitrogen surplus showed the opposite trend. The best performance was presented under the treatment of chemical fertilizer combined with 30000 kg·hm-2 of A. sinicus. Lime addition could increase grain nitrogen uptake, rice straw nitrogen uptake, and nitrogen use efficiency of rice, while reducing apparent nitrogen loss and nitrogen surplus, with the best performance of FM2+CaO. For all the treatments, the proportion of nitrogen absorbed by rice from A. sinicus was 6.3%-13.2%, while that from soil and chemical fertilizer was 86.8%-93.7%. The utilization ratio of A. sinicus nitrogen by rice was 23.8%-33.6%. The utilization ratio of A. sinicus nitrogen in different parts of rice was grain > stem and leaf > root. The residue rate of A. sinicus nitrogen in soil was 37.6%-62.4%. The loss rate of A. sinicus nitrogen was 7.8%-38.6%. Comprehensively considering nitrogen absorption and utilization of rice, nitrogen nutrient balance of rice-soil system, and the distribution situation of nitrogen from A. sinicus in rice, FM2+CaO was the optimum fertilization pattern in the study area.

Modulation of nitrate-induced phosphate response by the MYB transcription factor RLI1/HINGE1 in the nucleus

The coordinated utilization of nitrogen (N) and phosphorus (P) is vital for plants to maintain nutrient balance and achieve optimal growth. Previously, we revealed a mechanism by which nitrate induces genes for phosphate utilization; this mechanism depends on NRT1.1B-facilitated degradation of cytoplasmic SPX4, which in turn promotes cytoplasmic-nuclear shuttling of PHR2, the central transcription factor of phosphate signaling, and triggers the nitrate-induced phosphate response (NIPR) and N-P coordinated utilization in rice. In this study, we unveiled a fine-tuning mechanism of NIPR in the nucleus regulated by Highly Induced by Nitrate Gene 1 (HINGE1, also known as RLI1), a MYB-transcription factor closely related to PHR2. RLI1/HINGE1, which is transcriptionally activated by PHR2 under nitrate induction, can directly activate the expression of phosphate starvation-induced genes. More importantly, RLI1/HINGE1 competes with PHR2 for binding to its repressor proteins in the nucleus (SPX proteins), and consequently releases PHR2 to further enhance phosphate response. Therefore, RLI1/HINGE1 amplifies the phosphate response in the nucleus downstream of the cytoplasmic SPX4-PHR2 cascade, thereby enabling fine-tuning of N-P balance when nitrate supply is sufficient.

Integrated nitrogen management in rice (Oryza sativa) under system rice intensification

Rice (Oryza sativa L.) is the most important food crop cultivated in India with the average productivity of 2.9 t/ha. Rice has the largest yield potential crop which is to be tapped with sound management technologies like appropriate nutrient management techniques along with adoption of system rice intensification. To sustain present food sufficiency and to meet future food requirements, India has to realize an annual growth rate of at least 3% in productivity of rice. To maintain the nutritional standards, fertilizer nutrients should be applied in balanced and required proportion. Among the different nutritional elements, nitrogen (N) has received prime attention both by the farmers and researchers. Relationship among the growth, yield and nitrogen utilization in rice are becoming increasingly understood at the physiological and molecular level. Moreover, time and method of nitrogen application play a crucial role in increasing efficiency of fertilizers as well as the productivity of rice. This review paper attempts to document the different sources of nitrogen and its effect on growth and productivity of rice under system rice intensification.

Natural variation in OsGASR7 regulates grain length in rice.

Natural variation in OsGASR7 regulates grain length in rice.

Exploring the Potential of Overexpressed OsCIPK2 Rice as a Nitrogen Utilization Efficient Crop and Analysis of Its Associated Rhizo-Compartmental Microbial Communities.

Nitrogen (N) is one of the indispensable factors in rice growth and development. China holds a premier position in the production of rice and at the same time also faces higher N fertilizer costs along with serious damage to the environment. A better solution is much needed to address these issues, without disrupting the production of rice as an important cereal, while minimizing all the deleterious effects on the environment. Two isogenic lines Kitaake (WT) and its genetically modified line CIPK2 (RC), overexpressing the gene for Calcineurin B-like interacting protein kinase 2 (OsCIPK2) with better nitrogen use efficiency (NUE), were compared for their growth and development under low versus normal levels of N. NUE is a complex trait mainly related to a plant’s efficiency in extraction, assimilation, and recycling of N from soil. The microbial population was analyzed using high-throughput Illumina Miseq 16S rRNA sequencing and found that RC with CIPK2, specifically expressed in rice root, not only performed better without nitrogen fertilizer (LN) but also increased the diversity of bacterial communities in rice rhizosphere compartments (rhizosphere, rhizoplane, and endosphere). The relative abundance of beneficial bacteria phyla increased, which are known to promote the circulation and transformation of N in rhizosphere soil. To further explore the potential of RC regarding better performance under LN, the ion fluxes in root apical were detected by non-invasive micro-test technique (NMT). We found that RC can absorb more Ca2+ and NO3− under LN as compared to WT. Finally, compared to WT, RC plants exhibited better growth of root and shoot, and increased yield and N uptake under LN, whereas there was no significant difference in the growth of two rice lines under normal nitrogen (NN) treatment. We are able to get preliminary results, dealing with the OsCIPK2 overexpressed rice line, by studying the rice molecular, physiological, and chemical parameters related to NUE. The results laid the foundation for further research on N absorption and utilization in rice from the soil and the interaction with microbial communities.

Factors Affecting the Adoption of Agricultural By-Products as Feed by Beef Cattle Farmers in Maros Regency of South Sulawesi, Indonesia

The utilization of crop residue as a feed is very important because the arable land area is relatively limited. The study was aimed to examine the influence of adoption of crop-residue product as a feed. The research was conducted in Maros District by using survey methods from March to August 2015. The number of respondents was 96 farmers scattered throughout the Districts of Bantimurung and Camba as centers of rice, corn plant, and cattle productions. Questionnaires were used to collect data conducted by a trained enumerator. Survey was arranged using a logistic regression model to identify socio economic factors influencing the adoption of crop residue as a feed. Work perception (X2), contact with extension workers (X4), rice cultivated areas (X5), the number of livestock (X6), subjective norm (X7), and difficulty (X8) were socio-economic variables influencing the adoption of crop residue as a feed. However, the variables age (X1), farmer experiences (X3), and the number of family members (X9) had no effect on the adoption of this technology. In conclusion, extension workers play an important role in increasing the adoption of technology by using rice and corn straws as a feed. Likewise, not only the number of livestocks, but also the good perception of the farmers increased along with the increase of feed availability, such as utilization of rice and corn straws.

Nitrate-NRT1.1B-SPX4 cascade integrates nitrogen and phosphorus signalling networks in plants.

To ensure high crop yields in a sustainable manner, a comprehensive understanding of the control of nutrient acquisition is required. In particular, the signalling networks controlling the coordinated utilization of the two most highly demanded mineral nutrients, nitrogen and phosphorus, are of utmost importance. Here, we reveal a mechanism by which nitrate activates both phosphate and nitrate utilization in rice (Oryza sativa L.). We show that the nitrate sensor NRT1.1B interacts with a phosphate signalling repressor SPX4. Nitrate perception strengthens the NRT1.1B-SPX4 interaction and promotes the ubiquitination and degradation of SPX4 by recruiting NRT1.1B interacting protein 1 (NBIP1), an E3 ubiquitin ligase. This in turn allows the key transcription factor of phosphate signalling, PHR2, to translocate to the nucleus and initiate the transcription of phosphorus utilization genes. Interestingly, the central transcription factor of nitrate signalling, NLP3, is also under the control of SPX4. Thus, nitrate-triggered degradation of SPX4 activates both phosphate- and nitrate-responsive genes, implementing the coordinated utilization of nitrogen and phosphorus.

Effect of Irrigation Regimes and Soil Texture on the Potassium Utilization Efficiency of Rice

Understanding the effects of irrigation regime and soil texture on potassium-use efficiency (KUE) of rice (Oryza sativa. L) is essential for improving rice productivity. In this regard, experiments were conducted from July to October in 2016 and 2017 by using a randomized complete block design in a factorial arrangement with four replications. The rice plants were grown in three soils, with clay contents of 40%, 50%, and 60%, which were marked as S (40%), S (50%), and S (60%), respectively. For each soil type, irrigation regimes, namely, R (F, S100%), R (F, S90%), and R (F, S70%), were established by setting the lower limit of irrigation to 100%, 90%, and 70% of saturated soil water content, respectively, and the upper limit of irrigation with 30 mm of flooding water above the soil surface for all irrigation regimes. Results showed that the responses of the roots and shoots and the potassium accumulation (KA) and KUE of rice were significantly affected by the water regime and soil texture. In the same irrigation regime, increasing the soil clay content improved the K utilization of rice. Under the same soil type, R (F, S100%) was the optimal water management practice for growing rice. The R (F, S100%) S (60%) treatment presented the highest KUE, which was 56.4% in 2016 and 68.1% in 2017. The R (F, S70%) S (40%) treatment showed the lowest KUE, which was 13.8% in 2016 and 14.9% in 2017. These results enrich knowledge regarding the relationship among soil, water, and rice, and provide valuable insights on the effect of irrigation regime and soil texture on the KA and KUE of rice.

Effect of ozone stress on the absorption, distribution, and utilization of nitrogen in rice under different planting densities

High ozone (O3) can cause great damage to plants. However, the effect of high O3 on nitrogen (N) absorption, distribution, and utilization in rice at different growth stages under different planting densities is poorly understood. In the present study, a conventional cultivar (Yangdao 6) and a hybrid cultivar (II You 084) with different planting densities were exposed to an elevated amount of O3 (E-O3; 50% higher than that of the control, C-O3) under a free-air gas concentration enrichment (FACE) system. N absorption, distribution, and utilization of the green leaves, stems, and shoots at tillering, jointing heading, and maturity were investigated. Results showed that E-O3 significantly increased the N content in the shoots of Yangdao 6 by 7.5%, 12.7%, and 19.6%, respectively, at jointing, heading, and maturity. Also, the N content in the shoots of II You 084 increased by 5.4%, 6.5%, and 8.4% at the corresponding growth stage upon E-O3 application. E-O3 significantly decreased N accumulation of II You 084 by 8.3%, 4.9%, 4.7%, and 19.2%, respectively, at tillering, jointing, heading, and maturity. Further, E-O3 had a decreasing effect on the N distribution in green leaves (p ≤ 0.05) of both cultivars, but exerted an increasing effect on that in the stems of both cultivars (p ≤ 0.05). In addition, E-O3 significantly decreased the N use efficiency (NUE) for biomass of the two cultivars in all growth stages. These results revealed that E-O3 could increase the N content in rice plants but decrease the N accumulation and utilization in both cultivars. The effects of E-O3 on N absorption, distribution, and utilization were not affected by planting density.

Continuous applications of biochar to rice: Effects on nitrogen uptake and utilization

Improving soil quality is critical for increasing rice yield, and biochar could be a beneficial soil amendment for high yield. This study was conducted to determine the effects of continuous (repeated seasonal) applications of biochar on nitrogen (N) uptake and utilization in rice. A fixed field experiment was done in Yongan Town, Hunan Province, China, in six continuous seasons (the early and late rice-growing seasons from 2015 to 2017). Results showed that biochar application did not significantly affect soil N uptake in the first four seasons. The effect of biochar application on fertilizer N uptake was not significant in three of the first four seasons. In the fifth and sixth seasons, biochar application resulted in 14–26% increases in soil N uptake but 19–26% decreases in fertilizer N uptake. Soil N availability did not explain the increased soil N uptake with biochar application. The decreased fertilizer N uptake with biochar application was attributed to both decreased fertilizer N availability and increased N loss through ammonia volatilization. As a consequence of a compensation between the increased soil N uptake and the decreased fertilizer N uptake, the effect of biochar application on total N uptake was not significant in the fifth and sixth seasons. However, biochar application led to 7–11% increases in internal N use efficiency in the fifth and sixth seasons and 6% increase in grain yield in the sixth season. Our study suggests that the effects of repeated seasonal applications of biochar on N uptake and utilization in rice depend on the duration of biochar application. Longer continuous applications of biochar can increase internal N use efficiency and grain yield in rice with insignificant change in total N uptake.

Genetic variations in ARE1 mediate grain yield by modulating nitrogen utilization in rice

In crops, nitrogen directly determines productivity and biomass. However, the improvement of nitrogen utilization efficiency (NUE) is still a major challenge in modern agriculture. Here, we report the characterization of are1, a genetic suppressor of a rice fd-gogat mutant defective in nitrogen assimilation. ARE1 is a highly conserved gene, encoding a chloroplast-localized protein. Loss-of-function mutations in ARE1 cause delayed senescence and result in 10–20% grain yield increases, hence enhance NUE under nitrogen-limiting conditions. Analysis of a panel of 2155 rice varieties reveals that 18% indica and 48% aus accessions carry small insertions in the ARE1 promoter, which result in a reduction in ARE1 expression and an increase in grain yield under nitrogen-limiting conditions. We propose that ARE1 is a key mediator of NUE and represents a promising target for breeding high-yield cultivars under nitrogen-limiting condition.

Review of Rice: Production, Trade, Consumption, and Future Demand in Korea and Worldwide

Being a staple food for more than half of the population of the world and South Korea, rice is an important crop. For the past 20 years, global paddy rice cultivation area and production have shown an annual growth of 0.46% and 1.61%, respectively. Global rice consumption for food and processing has increased by 1.37% and 3.68%, respectively. Due to the main reason for such increasing human population, it is expected that from 439 million tons in 2010, additional 116 million tons will be needed in 2035. Global rice imports and exports have doubled in the last 20 years. However, in spite of such increment, global rice exports in 2013 were 8.4% of the total production. It is thought that rice protection policies in the producing countries are the main reason for such small scale of rice trading. In the past 5 years, India recorded the largest growth rate in rice exports (51.4%), whereas China showed the largest growth rate in imports (61.0%). For global utilization of milled rice during the same period, approximately 79.4% was used as food, 7.2% as animal feeds, and 1.4% for processing. Regionally, Asia has shown a similar pattern to the global rice usage, whereas utilization for processing in America, for food in Africa, and for animal feed in Europe was relatively higher than the global rice usage. Korea’s cultivation area and production since the last 5 years, are 0.5% and 0.8% of those of the world, respectively. Its annual rice export is approximately 3,000 tons, which is 0.01% of the global rice export. Korea’s rice utilization is high for food and low for feed and for processing relative to global rice utilization. Therefore, a review must be conducted to increase Korea’s utilization of rice for processing and for feed production.

Improvement in phosphate acquisition and utilization by a secretory purple acid phosphatase (OsPAP21b) in rice.

SummaryPhosphate (Pi) deficiency in soil system is a limiting factor for rice growth and yield. Majority of the soil phosphorus (P) is organic in nature, not readily available for root uptake. Low Pi‐inducible purple acid phosphatases (PAPs) are hypothesized to enhance the availability of Pi in soil and cellular system. However, information on molecular and physiological roles of rice PAPs is very limited. Here, we demonstrate the role of a novel rice PAP, OsPAP21b in improving plant utilization of organic‐P. OsPAP21b was found to be under the transcriptional control of OsPHR2 and strictly regulated by plant Pi status at both transcript and protein levels. Biochemically, OsPAP21b showed hydrolysis of several organophosphates at acidic pH and possessed sufficient thermostability befitting for high‐temperature rice ecosystems with acidic soils. Interestingly, OsPAP21b was revealed to be a secretory PAP and encodes a distinguishable major APase (acid phosphatase) isoform under low Pi in roots. Further, OsPAP21b‐overexpressing transgenics showed increased biomass, APase activity and P content in both hydroponics supplemented with organic‐P sources and soil containing organic manure as sole P source. Additionally, overexpression lines depicted increased root length, biomass and lateral roots under low Pi while RNAi lines showed reduced root length and biomass as compared to WT. In the light of these evidences, present study strongly proposes OsPAP21b as a useful candidate for improving Pi acquisition and utilization in rice.

Improving Rice Zinc Biofortification Success Rates Through Genetic and Crop Management Approaches in a Changing Environment.

Though rice is the predominant source of energy and micronutrients for more than half of the world population, it does not provide enough zinc (Zn) to match human nutritional requirements. Moreover, climate change, particularly rising atmospheric carbon dioxide concentration, reduces the grain Zn concentration. Therefore, rice biofortification has been recognized as a key target to increase the grain Zn concentration to address global Zn malnutrition. Major bottlenecks for Zn biofortification in rice are identified as low Zn uptake, transport and loading into the grain; however, environmental and genetic contributions to grain Zn accumulation in rice have not been fully explored. In this review, we critically analyze the key genetic, physiological and environmental factors that determine Zn uptake, transport and utilization in rice. We also explore the genetic diversity of rice germplasm to develop new genetic tools for Zn biofortification. Lastly, we discuss the strategic use of Zn fertilizer for developing biofortified rice.

Comparison of isotope methods for partitioning methane production and soil C priming effects during anaerobic decomposition of rice residue in soil

Management of rice residue in paddies often results in higher methane (CH4) emissions, but the carbon (C) sources contributing to higher emissions are not well characterized. We examined the relative contribution of soil and residue C sources for CH4 production in three different soils using both 13C-labeled or unlabeled (natural abundance) rice and maize residues. The results were compared to a recently proposed natural 13C abundance soil C partitioning method (CNAM) (Conrad et al. 2012b). As anticipated, residue addition increased CH4 production, with the timing and magnitude of emission varying across soils, likely due to differences in soil C and amount of electron acceptors. The CH4 derived from residue-C, when estimated using the typical 13C natural abundance method yielded either negative values or those exceeding 100%. Similarly, the CNAM frequently overestimated the contribution of residue C compared to the 13C enriched residue method (ERM). The over estimation is likely due to C isotopic fractionation during the utilization of rice and maize residues in the different soils. Substantial C isotope fractionation would bias the fundamental assumption of the CNAM. The ERM produced a consistent partitioning result of 50–70% of CH4 derived from residue additions. When typical minimum, average, and maximum values of natural 13C fractionation factors were applied to the ERM the partitioning outcome was unaffected. The priming effect of residue addition on CH4 production was regulated by electron acceptor concentrations in various soils and was positively correlated to the degree of residue decomposition. The priming effect of residue, therefore, depends both on soil and residue properties, with the ERM showing to be more accurate to account for the partitioning of CH4 from various C pools compared to CNAM.

Energy and nutrient utilization in rice (Oryza sativa)-weed ecosystem under post emergence herbicide application

A field experiment was carried out during 2010 and 2011 at the Research Farm of Krishi Nagar, J N Krishi Vishwa Vidyalaya, Jabalpur (Madhya Pradesh). The treatments consisted of weed control practices, viz. bispyribac sodium, penoxsulam, pyrazosulfuron-ethyl, cyhalofop-butyl + almix, fenoxaprop-p-ethyl + almix and control as main plot treatment and three day time application (morning, afternoon and evening) as sub plot treatment and laidout in split plot design in three replications. In rice (Oryza sativa L.)-weed ecosystem the solar energy utilization by weeds was maximum under control plot (836.46 and 786.52 lakh k cal/ha) where transplanting of crop was done without controlling of weeds, whereas pyrazosulfuron-ethyl treated plot registered lowest energy utilization (285.21 and 286.78 lakh k cal/ha) by weeds during both the years. The energy utilization by crop grain and straw was maximum with post emergence application of pyrazosulfuron-ethyl (527.83 and 533.65; 274.20 and 280.00 lakh k cal/ha). The studies on NPK removal by weeds and uptake by crop showed that the weed control treatments caused significant variations on these parameters. Application of pyrazosulfuron-ethyl also reduced the N (4.90 and 4.33 kg/ha), P (0.34 and 0.29 kg/ ha) and K (3.76 and 3.30 kg/ha) removal by weeds as compared to other herbicides and weedy check during both the years. The N (166.54 and 169.19 kg/ha), P (49.10 and 49.64 kg/ha) and K (170.95 and 173.13 kg/ha) uptake by crop was recorded higher with the application of pyrazosulfuron-ethyl. However, different day time application of post emergence herbicides was found statistically non-significant for energy and nutrient utilization by weeds and crop.

Agricultural production technology utilizing recent knowledge of plant nutrition science : 2. QTL approaches for understanding potential of nitrogen utilization in rice

Agricultural production technology utilizing recent knowledge of plant nutrition science : 2. QTL approaches for understanding potential of nitrogen utilization in rice

Fine characterization of OsPHO2 knockout mutants reveals its key role in Pi utilization in rice

Previous research using forward genetics approaches demonstrated that OsPHO2 regulates multiple phosphate-starvation responses in rice. In this work, we finely characterized two independent OsPHO2 knockout rice mutants under inorganic phosphate (Pi)-sufficient conditions. The ospho2 mutants exhibited defects in growth and reproductive development in the whole growing period. The cells in the elongation zone of ospho2 seedling roots were much shorter than those of the wild type. The phosphorus concentration in the blades of ospho2 mutants was 5.8-fold higher than those of wild-type plants, whereas it was only slightly higher in the sheaths, culms, spikelets, and seeds. Furthermore, Pi levels in the ospho2 mutants were highest in the oldest leaf and lowest in the youngest leaf, whereas there was no significant difference in the corresponding leaves of wild-type plants. These results suggest that ospho2 mutant phenotype results from a partial defect in Pi translocation and remobilization in the shoot of rice. This study thus provides evidence that OsPHO2, which functions at the downstream of OsPHF1, modulates Pi utilization by regulating the expression of Pht1 transporters in rice.

Characterization of Nitrogen Uptake and Utilization in Rice under Different Planting Methods

A field experiment was conducted with three planting methods including precision artificial transplanting with dry nursery middle and strong seedlings (AT), mechanical transplanting with small seedlings (MT) and direct seeding (DS) using early-maturing late japonica rice (EMLJ), late-maturing medium japonica rice (LMMJ) and medium-maturing medium japonica rice (MMMJ) (including conventional rice and hybrid rice). The results showed that the N content and uptake in plants were DSMTAT at jointing and ATMTDS at heading and maturity. Total N uptake at maturity with AT was 11.68% and 39.03% higher than that with MT and DS and that with MT was 24.49% higher than that with DS. N uptake rate was DSMTAT before jointing and ATMTDS from jointing to heading and from heading to maturity. Maximum N uptake rate of AT and MT appeared in the period from jointing to heading, and that of DS with MMMJ appeared from jointing to heading while that with EMLJ and LMMJ appeared before jointing. N periodic accumulation from jointing to heading and from heading to maturity were ATMTDS and the difference among different planting methods all reached significant or very significant level. N recovery efficiency of AT, MT and DS were 44.49%, 39.00%, and 31.41%, respectively. N recovery efficiencies among different varieties with AT and MT were EMLJLMMJMMMJ, and that with DS was MMMJLMMJEMLJ, and in the case for the same type of variety, that of conventional japonica rice was higher than that of hybrid japonica rice. N requirement for 100 kg grain of AT, MT, and DS were 1.959 (1.900–2.009), 1.842 (1.681–1.914), and 1.638 (1.540–1.721) kg, respectively. It was no significant differencebetween AT and MT while both were significantly higher than that of DS for conventional japonica rice. For hybrid japonica rice, the differences among different planting methods were all significant. N requirement for 100 kg grain among different growth type of varieties with DS was MMMJLMMJEMLJ while that with AT and MT was not significantly different. It is important to select scientific planting method and suitable variety type for achieving effective nitrogen uptake and utilization.

Effects of Different Paddy Field Drainage Degrees and Panicle Nitrogen Fertilizer Managements on Photosynthetic Productivity and Nitrogen Utilization of Rice under Triangle-Planted System of Rice Intensification

The effects of different paddy field drainage degrees including three soil water content levels(0-20 cm soil relative water content was controlled at 80%±5%,60%±5%,and 40%±5%,named W 1,W 2,and W 3 respectively) and three panicle nitrogen fertilizer managements(the first panicle nitrogen fertilizer was applied on the 1st,8th,and 15th days after rewatering,named S 1,S 2,and S 3,respectively) on photosynthetic productivity during filling stage and nitrogen utilization of rice were investigated using medium hybrid rice Ⅱ you 498 under triangle-planted system of rice intensification(TSRI).The results showed that there was an obvious interaction to photosynthetic productivity,dry matter accumulation and nitrogen uptake,translocation and utilization between paddy field drainage degree and panicle nitrogen fertilizer management.Paddy field drainage had the most significant effect compared with panicle nitrogen fertilizer management.Canopy apparent photosynthetic rate at 15 days and 30 days and effective panicle number were decreased,under the treatment of applying the first panicle nitrogen fertilizer on the 1st day after rewatering,and canopy apparent photosynthetic rate at 15 days and 30 days after heading,harvest index and N production efficiency were increased under the treatment of applying the first panicle nitrogen fertilizer on the 8th or 15th day after rewatering in lower paddy field drainage condition(W 1).The treatment with higher paddy field drainage condition(W 2,W 3) applying the first panicle nitrogen fertilizer on the 1st or 8th days after rewatering was favorable to improve flag leaf photosynthetic rate at booting and full heading stages,canopy apparent photosynthetic rate at 15 days and 30 days after heading,dry matter accumulation,grain yield and its components,and nitrogen accumulation and utilization.From the comprehensive analysis and comparison,W 2 S 1 is the optimum combination for moderate paddy field drainage degree and panicle nitrogen fertilizer management under theTSRI,and its grain yield reached 10.96 t ha-1.