Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper(BPH) Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1(TN1) in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.     

Serological specificity of leaf streak pathogen of rice

The leaf streak of rice is one of the seedborne and quarantine bacterial disease in China. The rice seeds must be strictly inspected to prevent the disease from spreading. The serological test is a rapid and accurate method of identifying seedborne bacterial plant pathogens. But the specificity and thus reliability of any serological method depend first on the specificity of the antiserum. Therefore, a high specificity of antiserum is always required for and has become a key in detecting the leaf streak pathogen in rice seeds. The present study was conducted on the method of improving the specificity. Two group of antigen, the yellow and white proteins, were extracted from the cells of Xanthornonas oryzae pv. oryzicola by the methods of stepwise precipitation with ammonium sulfate and differential centrifugation. Antiserum A and B against the yellow and white proteins were each produced in white rabbit immunized with the proteins respectively. The tittle of the two antiserum were the same(1: 6400).     

Regulation of GAs-binding protein on dwarfism of rice （Oryza sativa L.）

The levels of endogenous hormones (GAs and ABA) in rice seedlings (7d) were measured by gas-liquid chromatography with flame ionization detoctor (GLC-FID) and the GAs-binding protein on meanbrane of young rice shoot was also analysed as dascribed by Chiharu.     

Preliminary Study on Resistance of the Rice Stem Borer （Chilo Suppressalis） to Fipronil

By means of topical application, fipronil resistance was surveyed in the rice stem borer, Chilo suppressalis, from 12 diferent areas in east China from 2001 to 2004. The rice stem borers in most regions of Jiangsu and Anhui were still susceptible to fipronil. But in Wuxi, Jiangsu Province and Cixi, Zhejiang Province, their sensitivity became decreased （resistance ratios were 3.1 and 3.6, respectively）, and the medium level of resistance （resistance ratio was 21.2） was found in Cangnan, Zhejiang Province. So, it was still at the early stage for fipronil resistance development in this pest. Synergism experiments showed that piperonyl butoxide（PBO） had a little effect on both susceptible and resistant borers （synergism ratios were 1.1-1.2）. Though triphenyl phosphate （TPP） and diethyl meleate （DEM） had no effect on the susceptible borers, they had significant synergism on fipronil in the resistant population to fipronil （synergism ratios were 1.8 and 1.6, respectively）, indicating esterase and glutathion S-transferase may be involved in the resistance mechanism. Bioassay with currently used insecticides indicated that triazophos （because of high resistance）, trichlorphon and acephate had very low toxicity to resistant borers. But diazinon, pyridaphenthion, decamethrin and avermeatin showed high toxicity and had no cross resistance to fipronil, which could be considered as substitute insecticides in the resistance managment.     

Exploitation of genetic variation caused by space treatment in rice

Seeds of early indica rice varieties 6188, D6049, of late indiea rice varieties Minghui 63, Xiangge, Waiqi, 70321, and late japonica rice variety Beik 15 were carried by the retrieved satellite "921006" in order to investigate the comprehensive effects of the space factors. Treated seeds and untreated seeds (CK) were grown in the field. The results showed that although compared with the CK (which was very uniform) small differences on population uniformity, plant height, growth duration and seed setting rate were observed, no segregation was found in SP_1. Strong segregation occurred in SP_2 and SP_3 generations. Significant difference on the grain yield of Single plant was observed between SP_2 and CK, while the yield between     

Rapid Determination of Silicon Content in Rice

A method for rapid determination of silicon content in rice was introduced. The reliability of this method was verified by using a recombinant inbred line （RIL） population of rice cross Zhenshan 97B / Milyang 46. Two hundred and forty-nine RILs were transplanted in two replications. Simple correlation coefficients on the silicon content in the hull, flag leaf and stern in rice between duplicate samples of 498 rice materials were 0.97954, 0.97026 and 0.98848, respectively. Ten representative samples were selected for measurement using the high-temperature alkaline fusion method. Simple correlation coefficient between the silicon contents determined by the high-temperature alkaline fusion method and by the present method is 0.9993.     

Comparative Efficacies of Next-Generation Insecticides Against Yellow Stem Borer and Their Effects on Natural Enemies in Rice Ecosystem

The efficacies of some next-generation insecticides against the rice yellow stem borer(YSB),Scirpophaga incertulas(Walk.), and their compatibilities with natural enemies were investigated during 2014 and 2015. Three newer insecticides, chlorantraniliprole 0.4% G, dinotefuran 20% SG, and methoxyfenozide 24% SC, and two commonly used insecticides, carbufuran 5 G and quinalphos 25 EC,were evaluated in the field for their efficacies against YSB and their non-target effects on natural enemies.Application of chlorantraniliprole 0.4% G at 10.96 kg/hm^2 resulted in the greatest reduction in YSB infestation(deadhearts and whiteheads) and greatest increase of yield compared to the untreated control plots, followed by methoxyfenozide 24% SC at 0.41 L/hm^2, dinotefuran 20% SG at 0.15 kg/hm^2,carbufuran 5 G at 10.96 kg/hm^2, and quinalphos 25 EC at 1.50 L/hm^2. All the insecticides reduced the numbers of predators viz., lady bird beetles, wolf spiders, carabid beetles, earwigs, green mirid bugs, and damselflies. Numbers of adults of the egg parasitoids Trichogramma sp., Telenomus sp. and Tetrastichus sp. were significantly reduced in insecticide-treated plots compared to untreated control plots. In all field trials, the harmful effects of the five insecticides were in the following rank order(least harmful to most harmful): chlorantraniliprole 0.4% G, carbufuran 5 G, dinotefuran 20% SG, methoxyfenozide 24% SC,and quinalphos 25 EC. On the basis of reduction in YSB infestation, increase in grain yield, and compatibility with natural enemies, chlorantraniliprole 0.4% G was proved to be the best of all the insecticides for YSB management system, although the study suggested minimizing its retail price for enhancement of cost effectiveness in farmers' fields.     

Research outline on rice genetics in China

In 1928, studies on the inheritance and evolution of wild rice conducted by Prof TING Yin and the linkage relationship between genes controlling rice wax endosperm and glume top colour by Prof ZHAO Lianfang were reported. Since then, a large number of researches on rice genetics have been carried out in China,     

Effects of Different Nitrogen Fertilizer Levels on Fe, Mn, Cu and Zn Concentrations in Shoot and Grain Quality in Rice （Oryza sativa）

In a pot experiment, effects of N fertilizer application on the concentrations of Fe, Mn, Cu and Zn in shoot of rice and the quality of brown rice were studied. In the treatments with N fertilizer application, the concentrations of Fe, Mn, Cu and Zn in most parts of rice shoot increased compared with control (no N fertilizer application). This indicated that the transportation ability of microelements from root to shoot in rice was improved with N fertilizer application. Effect of N fertilizer on IR68144 was similar to that of on IR64, but the concentrations of the microelements in plant differed, suggesting that the characteristic expression of the two rice genotypes was not controlled by the amount of N fertilizer supplied. The concentrations of those microelements in brown rice increased at first and then decreased with increasing N fertilizer application, reaching the highest at 160 kg/ha, at which the Fe, Mn, Cu and Zn concentrations in brown rice increased by 28.96%, 41.34%, 58.31% and 16.0% for IR64, and by 22.16%, 13.75%, 8.75% and 20.21% for IR68144 compared with control, respectively. Moreover, N fertilizer promoted the accumulation of protein, decreased the accumulation of amylose in grain, and enhanced gel consistency of brown rice. These results indicate that appropriate N fertilizer management could increase micronutrient contents in grain and improve nutrition quality of rice.     

Preliminary study on effects of magnetizing seeds of rice

Magnetizing seeds of crops has been a new agrophysical technique in recent years. The experiment of magnetized rice seeds by Seed-Magnetizer was conducted in Yuping Dongzu Autonomous County, Guizhou Province, China in 1991. The seeds of three rice varieties (Wenyou 3, Shuanggui and Teqing) were treated with SG-I Seed-Magnetizer.They passed through the Seed-Magnetizer with the passing rate 4000g / min for three separate times. The magnetic field gradient was 10t/m and the magnetic flux 6.5×10~4 t / m~2. And then, the magnetized seeds and non-magnetized seeds (CK) were simultaneously sowed on Apr 24, transplanted on     

Analysis of genetic relationships between grain milling quality traits and plant agronomic traits of rice

Since seed and maternal plant are in different generations, the grain milling traits and plant agronomic traits ot rice are based on different genetic models. Using the genetic models which could estimate covariance components between two traits with unequal design matrices, we analyzed the gentic relationships between grain milling traits and plant agronomic traits. Nine cytoplasmic male sterile (CMS) lines (Zhenshan 97 A and others) and five restoring lines (T 49 and others) of indica rice were used in an incomplete diallel cross. Seedlings of parents and F_1s were planted in the field at Zhejiang Agri Univ in 1994. There were 24 plants in each plot with three replications. Plant agronomic traits were determined from eight plants in the middle part of the plot. Seed samples of parents, F_1 and F_2s were used for analyzing milling quality traits of rice. It was indicated by the results (See table) that stronger genotypic relationships were existed according to genotypic covariances (C_(G/G)) between th     

Physiological Age Status of Female Adults and Off-Season Survival of Rice Leaffolder Cnaphalocrocis medinalis in India

Rice leaffolder, Cnaphalocrocis medinalis, is one of the major foliage feeders found in the rice growing regions in India. When the crop was at maturity, numerous adults of rice leaffolder were found in the rice fields though the larval population gradually decreased, and no eggs were found on rice leaves. The population characteristics of C. medinalis were assessed based on the physiological age status of adults at different crop growth stages. Based on egg development within ovarioles, ovariole appearance, number and colour of fat bodies, and characteristics of bursa copulatrix, physiological age status of the adults was described, which served as a basis for the determination of age composition. C. medinalis adults were found during the first week of August on rice plants, of which 44% were in Age 0 with immature ovaries, indicating immigrants. However, 28% adults each were at Ages 1–2 with developing ovaries, indicating local breeding population. The carryover and off-season survival of C. medinalis were also studied to determine the contribution of the alternative hosts in the population growth that helped in devising efficient management strategies. Rice was the most preferred host followed by Triticum aestivum, Echinochloa crusgulli and Brachiaria plantaginea. Various routes of the carryover of C. medinalis from season to season were discussed.     

Effects of 1,2,4-Trichlorobenzene and Mercury Ion Stress on Ca^2＋ Fluxion and Protein Phosphorylation in Rice

The effects of 5 mg/L 1,2,4-trichlorobenzene (TCB) and 0.1 mmol/L mercury ion (Hg2 ) stresses on Ca2 fluxion and protein phosphorylation in rice seedlings were investigated by isotope exchange kinetics and in vitro phosphorylation assay. The Ca2 absorption in rice leaves and Ca2 transportation from roots to leaves were promoted significantly in response to Hg2 and TCB treatments for 4-48 h. The Ca2 absorption peaks presented in the leaves when the rice seedlings were exposed to Hg2 for 8-12 h or to TCB for 12-24 h. Several Ca2 absorption peaks presented in the roots during rice seedlings being exposed to Hg2 and TCB, and the first Ca2 absorption peak was at 8 h after being exposed to Hg2 and TCB. The result of isotope exchange kinetic analysis confirmed that short-term (8 h) Hg2 and TCB stresses caused Ca2 channels or pumps located on plasmalemma to open transiently. The phosphorylation assay showed that short-term TCB stress enhanced protein phosphorylation in rice roots (TCB treatment for 4-8 h) and leaves (TCB treatment for 4-24 h), and short-term (4-8 h) Hg2 stress also enhanced protein phosphorylation in rice leaves. The enhancement of protein phosphorylation in both roots and leaves corresponded with the first Ca2 absorption peak, which confirmed that the enhancement of protein phosphorylation caused by TCB or Hg2 stress might be partly triggered by the increases of cytosolic calcium. TCB treatment over 12 h inhibited protein phosphorylation in rice roots, which might be partly due to that TCB stress suppressed the protein kinase activity. Whereas, Hg2 treatment inhibited protein phosphorylation in rice roots, and Hg2 treatment over 12 h inhibited protein phosphorylation in rice leaves. This might be attributed to that not only the protein kinase activity, but also the expressions of phosphorylation proteins were restrained by Hg2 stress.     

Grain multi-types of ancient cultivated rice of Bashidang ruins in Lixian County of Hunan Province

Researches on ancient cultivated rice have always attracted great attention owing to its importance for exploring the origin and evolution of rice, but little is understood.Two hundred grains of ancient cultivated rice 8000 BC were unearthed in Bashidang ruins in Lixian County. T43-18 were measured for the length, width, and thickness,     

Effects of 4PU-30 on leaf senescence and degration of protein and nucleic acid in rice

4PU—30[N—phenyl—'N—(2—chloro—4—pyridyl) urea] is a new type of plant growth regulator with cytokinin properties. It has been confirmed to delay rice leaf senescence effectively. In order to elucidate the physiological role of 4PU—30 in delaying senescence, the changes of protein, nucleic acid contents, and the related activities of degradative enzymes were studied. Shanyou 63, an indica hybrid rice was used for this experiment. In the in vitro experiment, two full—developed leaves from the top during heading stage were collected and cut into 5.0cm segments, They were floated on the surface of distilled water containing 0.1mg/14PU—30 and incubated in darkness at 30 C. The leaves floated on distilled water were used as control.It was observed that chlorophyll content in controlled leaves declined rapidly started from the second day and dropped by 93.4% on the 6th day while that in leaves treated with 4PU—30 declined by 41.4% only. During senescence, specific activities of hemoglobin—digesting     

Rice Germplasm Resources in China

Editor-in-chief: Prof. YING Cunshan The book is written by 80 experienced experts on rice germplasm resources from CNRRI and other research institutes in China. Fourteen comprehensive reviews were chapterly arranged in its first part, and reflected the advances of all aspects related to the research of rice germplasm resources in China, including: The origin, evolution and classification of cultivated rice     

Effect of Nitrogen on Water Content, Sap Flow, and Tolerance of Rice Plants to Brown Planthopper, Nilaparvata lugens

Water content (WC) and sap flow from leaf sheath of rice plants with varying nitrogen levels at different growth stages, and fluctuations in relative water content (RWC) of rice plants being damaged by brown planthoppcr (BPH), Nilaparvata lugens were determined in the laboratory, and the tolerance of rice plants to BPH at different nitrogen regimes was evaluated in the greenhouse at International Rice Research Institute (IRRI), the Philippines. The results indicated that both WC and RWC were increased significantly, as the amount of sap flow from rice plants was reduced statistically, with the increase of nitrogen content in rice plants. RWC in rice plants applied with high nitrogen fertilizer decreased drastically by the injury of BPH nymphs, while the reduced survival duration of rice plants with the increase of nitrogen content was recorded. These may be considered to be one of the important factors in increasing the susceptibility to BPH damage on rice plants applied with nitrogen fertilizer.     

High Temperature Modifies Resistance Performances of Rice Varieties to Brown Planthopper,Nilaparvata lugens(Stl)

To investigate the effect of temperature on the resistance characteristics of rice varieties with different resistance genes to brown planthopper(BPH),Nilaparvata lugens(Stl),the resistances of IR26(Bph1)and IR36(bph2)to BPH population in Hangzhou,China were monitored in greenhouse during September in 2007 and 2008 by using the standard seedling screening techniques(SSST)developed by the International Rice Research Institute(IRRI).Furthermore,the changes in resistance of IR26 and IR36 to BPH,soluble sugar and oxalic acid contents in 25-day-old rice plants of susceptible variety TN1 and resistant varieties IR26 and IR36 were detected at five temperatures(22℃,25℃,28℃,31℃ and 34℃).IR26 completely lost resistance both in greenhouse and at the five tested temperatures.IR36 still had moderate resistance at natural temperature,but its resistance decreased gradually when the temperature increased from 25℃ to 34℃,and fully lost its resistance at 31℃ and 34℃.The highest durable resistance of IR26 and IR36 were recorded at 25℃.The soluble sugar content in plants of the three tested rice varieties increased with temperature increase,and the oxalic acid content increased with the temperature increase at first,maximized at 25℃,and then declined.Two-way ANOVA indicated significant effects of temperature and rice variety on contents of soluble sugar and oxalic acid in rice plants.     

Practices and Prospects of Super Hybrid Rice Breeding

The great progress in super rice breeding both in China and other countries has been made in recent years. However, there were three main problems in super rice breeding: 1) the super rice varieties were still rare; 2) most super rice varieties exhibited narrow adaptability; and 3) current breeding theories emphasized too much on the rice growth model, but they were unpractical in guidance for rice breeding. According to the authors’ experience on the rice breeding, the breeding strategies including three steps (super parent breeding, super hybrid rice breeding and super hybrid rice seed production) were proposed, and the objectives of each step and the key technologies to achieve the goals were elucidated in detail. The super parent of hybrid rice should exhibit excellent performance in all agronomic traits, with the yield or sink capacity reached the level of the hybrid rice control in regional trials. The super hybrid rice combination should meet the following criteria: good rice quality, wide adaptation, lodging resistance, resistance to main insects and diseases, and the yield exceeded above 8% over the control varieties in the national and provincial regional trials. To achieve the goal, the technical strategies, such as selecting optimal combination of the parents, increasing selection pressure, paying more attention to harmony of ideal plant type, excellent physiological traits and all the agronomic traits, should be emphasized. The yield of seed production should reach 3.75 t/ha and 5.25 t/ha for the super hybrid rice combinations derived from early-season and middle-season types of male sterile lines, respectively. The main technologies for raising seed production yield included selecting optimum seed production site, using the male sterile line with large sink capacity and good outcrossing characteristics, and improving the amount of the pollen by intensive cultivation of the male parent. According to the technologies of the three-step breeding on super hybrid rice, two super rice parents, including a male parent 996 and a thermo(photo)-genic male sterile [T(P)GMS] line C815S, were bred. Furthermore, a super early hybrid rice combination, Luliangyou 996, which could be used as a double-season early rice variety in middle and lower reaches of the Yangtze River, China, was bred by using the super rice variety 996 as the male parent, and several hybrid rice combinations with higher yield than control variety in regional trials both of Hunan Province and state were bred with the T(P)GMS line C815S as the female parent.     

Physiological Mechanism of Salicylic Acid for Alleviation of Salt Stress in Rice

Soil salinity is one of the most important problems of crop production in estuarine and coastal zones. Improvement in salt tolerance of major food crops is an important way for the economic utilization of coastal zones. This study proved that the application of salicylic acid(SA) improved the growth and yield under salt stress conditions and investigated its physiological mechanisms for salt tolerance. The investigation on the effect of SA for salt tolerance during germination showed that the decreased rates of germination and growth(in terms of shoot and root lengths) by the salt stress were significantly increased by the SA application(SA + NaCl). The treatment of SA to the high and low saline soils enhanced the growth, yield and nutrient values of rice. The effects of SA on Na~+, K~+ and Cl~– ionic accumulation were traced under salt stress condition by inductively coupled plasma optical emission spectrometry and ion chromatography. It was revealed that the increased accumulation of Na~+ and Clˉ ions by the salt stress were reduced by SA application. An increased concentration of endogenous SA level was detected from the SA-treated rice varieties(ASD16 and BR26) by liquid chromatography electrospray Ionization-tandem mass spectrometry. The activities of antioxidant enzymes such as superoxide dismutase, catalase and peroxidase were increased by salt stress whereas decreased by the SA application. The study proved that the application of SA could alleviate the adverse effects of salt stress by the regulation of physiological mechanism in rice plants. In spite of salt stress, it can be applied to the coastal and estuarine regions to increase the rice production.