摘要：
This study was conducted to compare super hybrid varieties with inbred varieties. Three varieties from each varietal group were grown under three sowing dates in Changsha, Hunan Province, China in 2010. Grain yield and some-yield-attributes such as tillering process, panicle traits and biomass production were measured for each variety. Averaged across three sowing dates, grain yield of super hybrid varieties was 26% higher than that of inbred varieties. The high grain yield of super hybrid varieties was attributed to improvement in both sink and source. Super hybrid varieties had large panicle size than inbred varieties, which was achieved not at the expense of panicle number. The large panicles of super hybrid varieties were attributed to more spikelets per panicle due to more secondary branches per panicle or spikelet volume. Strong tillering ability played a critical role in maintaining the panicle number for super hybrid varieties. Super hybrid varieties produced more biomass than inbred varieties, and this advantage was observed as early as seedling stage. High seed amylase activity was partially responsible for high biomass production for seedlings of super hybrid varieties. Canopy structure was improved in super hybrid varieties and reflected in large top three leaves and panicle position within the canopy. Higher total biomass production of super hybrid varieties resulted from both ,long growth duration and high crop growth rate.
摘要：
To determine the effect of wide plant spacing on yield formation of hybrid rice in southern China, a field experiment was conducted in Wuzhou, Guangxi Province in late rice-growing season in 2010. Grain yield, yield components and biomass production of two hybrid rice cultivars (Liangyoupeijiu and II-you 602) were compared between wide (20 x 27 cm) and normal plant spacings (16 x 23 cm). Wide plant spacing produced 10% lower grain yield than normal plant spacing for Liangyoupeijiu, while for II-you 602 the difference was consistent but not significant. For Liangyoupeijiu, wide plant spacing had 12% more spikelets per cm panicle but 13% lower spikelet filling percentage and 4% smaller grain weight than normal plant spacing. Aboveground biomass, harvest index and crop growth rate were less under wide plant spacing than under normal plant spacing by 10, 2 and 9%, respectively. Wide plant spacing is unsuitable for hybrid rice production in southern China.
关键词：
super hybrid rice;yield;panicle number;panicle size
摘要：
Chinese super hybrid rice breeding project has developed many new varieties with great yield potential. It is controversial which yield component should be emphasized in super hybrid rice production. The present study was conducted to compare super hybrid rice with common hybrid and super inbred rice and analyze contributions of yield components to grain yield of super hybrid rice under experimental conditions, and evaluate relationships between grain yield and yield components of super hybrid rice in farmer’s paddy fields. Field experiments were done in Changsha, Guidong, and Nanxian, Hunan Province, China, from 2007 to 2009. Eight super hybrid varieties, one common hybrid variety, and one super inbred variety were grown in each location and year. Rice production investigation was undertaken in high-yielding （Guidong）, moderate-yielding （Nanxian）, and low-yielding （Ningxiang） regions of Hunan Province, China, in 2009. Grain yield and yield components were measured in both the field experiments and rice production investigation. Super hybrid rice varieties outyielded common hybrid and super inbred varieties across three locations and years. Yield potential has been increased by 11.4% in super hybrid rice varieties compared with common and super inbred varieties. The higher yield of super hybrid varieties was attributed to improvement in panicle size. Panicles per m2 had the highest positive contribution to grain yield with the exception under yield level of 10.0 to 12.0 t ha-1, and was positively related to grain yield in farmer’s field at all of the high-, moderate-, and low-yielding regions. Our study suggests that panicle per m2 ought to be emphasized in super hybrid rice production.
作者：
Hu Xin-xi;Nie Xian-zhou*;Song Yong;Xiong Xing-yao;Tai Helen
期刊：
Agricultural Sciences in China,2011年10(4):544-552 ISSN：1671-2927
通讯作者：
Nie Xian-zhou
作者机构：
[Hu Xin-xi; Tai Helen; Nie Xian-zhou; Song Yong] Agr & Agri Food Canada, Potato Res Ctr, Saskatoon, SK, Canada.;[Hu Xin-xi; Xiong Xing-yao; Song Yong] Hunan Agr Univ, Coll Hort & Landscape, Hunan Prov Engn Res Ctr Potatoes, Changsha 410128, Hunan, Peoples R China.;[Nie Xian-zhou] Agr & Agri Food Canada, Potato Res Ctr, POB 20280, Saskatoon, SK, Canada.
通讯机构：
[Nie Xian-zhou] A;Agr & Agri Food Canada, Potato Res Ctr, POB 20280, Saskatoon, SK, Canada.
关键词：
ethylene;TCDVd;tomato;interaction
摘要：
To investigate whether ethylene is involved in tomato plants in response to the invasion of viroid, tomato cv. Pearson and its ethylene-insensitive mutant Never ripe (Nr) was challenged with Tomato chlorotic dwarf viroid (TCDVd). Both Pearson and Nr plants developed various symptoms including dwarf, bunch, reduced leaf size, leaf chlorosis, and necrosis at 3-wk-post-inoculation and thereafter even though the stunting in Nr was not as severe as in Pearson plants. The sizes of fruits were also significantly reduced in the viroid-infected plants. Treatments of Pearson with ethephon, an ethylene- releasing compound, mimicked TCDVd in induction of stunting and pathogenesis-related (PR) genes in the plants. Pretreatment of Pearson plants prior to TCDVd-inoculation or ethephon application with silver thiosulfate (STS), an ethylene action inhibitor, partially suppressed the viroid- or ethephon-induced symptoms as well as PR gene expression. In addition, Nr and STS-treated Pearson exhibited a slightly lower viroid titre in comparison to the control Pearson plants. These results suggest that ethylene is involved but plays a limited role in TCDVd-induced symptom development.
摘要：
Simplified cultivation technologies for rice have become increasingly attractive in recent years in China because of their social, economical and environmental benefits. To date, several simplified cultivation technologies, such as conventional tillage and seedling throwing (CTST), conventional tillage and direct seeding (CTDS), no-tillage and seedling throwing (NTST), no-tillage and direct seeding (NTDS) and no-tillage and transplanting (NTTP), have been developed in China. Most studies have shown that rice grown under each of these simplified cultivation technologies can produce a grain yield equal to or higher than traditional cultivation (conventional tillage and transplanting). Studies that have described the influences of agronomic practices on yield formation of rice under simplified cultivation have demonstrated that optimizing agronomy practices would increase the efficiencies of simplified cultivation systems. Further research is needed to optimize the management strategies for CTST, CTDS and NTST rice which have developed quickly in recent years, to strengthen basic research for those simplified cultivation technologies that are rarely used at present (such as NTTP and NTDS), to select and breed cultivars suitable for simplified cultivation and to compare the practicability and effectiveness of different simplified cultivation technologies in different rice production regions.
通讯机构：
[Ma, Hao] N;Nanjing Agr Univ, State Key Lab Crop Genet & Germplasm Enhancement, Nanjing 210095, Jiangsu, Peoples R China.
摘要：
To obtain salt tolerant genotypes, salt tolerance of 10 jute genotypes of different origins was evaluated by relative salt harm rate at germination stage and by index of salt harm at seedling stage, respectively. The results indicated that salt tolerance of germination stage of jute was consistent with that of seedling stage, with a markedly significant (P < 0.01) correlation of 0.8432 (n =10). Two high salt tolerant genotypes (Huang No.1 and 9511) and two salt sensitive genotypes (Mengyuan and 07-21) were screened out by these methods. Further activity analysis of POD, SOD and CAT and determination of MDA content at seedling stage validated that genotypes Huang No.1 and 9511 were more salt tolerant than genotypes Mengyuan and 07-21. Our results indicated that the combination of relative salt harm rate at germination stage and index of salt harm at seedling stage can be used to evaluate salt tolerance of jute genotypes.
作者机构：
[Chen Li-yun; Lei Dong-yang; Tang Wen-bang; Xiao Ying-hui] Hunan Agr Univ, Rice Res Inst, Changsha 410128, Hunan, Peoples R China.
通讯机构：
[Chen, LY ] ;Hunan Agr Univ, Rice Res Inst, Changsha 410128, Hunan, Peoples R China.
关键词：
two-line hybrid rice;dual-purpose genic male sterile line;photoperiod;and temperature characteristics;seed production;seed propagation
摘要：
The main problems about research and application of two-line hybrid rice were reviewed, including the confusing nomenclature and male sterile lines classification, the unclear characteristics of photoperiod and temperature responses and the unsuitable site selection for male sterile line and hybrid rice seed production. In order to efficiently and accurately use dual-purpose genic male sterile lines, four types, including PTGMS (photo-thermo-sensitive genic male sterile rice), TGMS (thermo-sensitive genic male sterile rice), reverse PTGMS and reverse TGMS, were proposed. A new idea for explaining the mechanism of sterility in dual-purpose hybrid rice was proposed. The transition from sterile to fertile was involved in the cooperative regulation of major-effect sterile genes and photoperiod and/or temperature sensitive ones. The minor-effect genes with accumulative effect on sterility were important factors that affected the critical temperature of sterility transfer. In order to make better use of dual-purpose lines, the characterization of responses to photoperiod and temperature of PTGMS should be made and the identification method for the characterization of photoperiod and temperature responses of PTGMS should also be put forward. The optimal ecological site for seed production could be determined according to the historical climate data and the requirements for the meteorological conditions during the different periods of seed production.
关键词：
Direct seeding;Panicle number;Panicle size;Physiological factor;Super hybrid rice
摘要：
Super hybrid rice Liangyoupeijiu was grown by transplanting (TP) at a spacing of 20 cm x 20 cm with one seedling per hill and by direct-seeding (DS) at a seeding rate of 22.5 kg ha(-1) (about 120 seeds m(-2)) in Changsha, Hunan Province, China in 2004-2010. Grain yield and yield components were measured each year, and some physiological factors were determined in 2009. There was no significant difference in mean grain yield across years between DS and TP. DS produced more panicles per m(2) but less spikelets per panicle than TP. The differences in number of spikelets per m(2), spikelet filling percentage and grain weight between DS and TP were not significant. A large number of panicles per m(2) in DS was derived from the increased number of tillers per m(2) rather than increased rate of panicle-bearing tillers, and the number of tillers per m(2) was mainly determined by the number of hills per m(2) because the number of tillers per hill was small in DS plants. Tillering rate, tillering duration as well as carbohydrate and nitrogen metabolism were critical to the reduced number of tillers per hill in DS. In DS plants with fewer spikelets per panicle, the numbers of primary branches and secondary branches per panicle, spikelets per primary and secondary branches, and also panicle length and spikelets per unit panicle length were smaller. These differences were attributed to the smaller source leaf size as well as lower root activity and the nutritional status at panicle initiation.
摘要：
In future climates, rice crops will be frequently exposed to water deficit and heat stress at the most sensitive flowering stage, causing spikelet sterility and yield losses. Water deficit alone and in combination with heat stress significantly reduced peduncle elongation, trapping 32% and 55% of spikelets within the leaf sheath, respectively. Trapped spikelets had lower spikelet fertility (66% in control) than those exserted normally (>93%). Average weighted fertility of exserted spikelets was lowest with heat stress (35%) but higher with combined stress (44%), suggesting acquired thermo-tolerance when preceded by water-deficit stress. Proteins favoring pollen germination, i.e., pollen allergens and beta expansin, were highly up-regulated with water deficit but were at normal levels under combined stress. The chaperonic heat shock transcripts and proteins were significantly up-regulated under combined stress compared with either heat or water deficit. The importance of spikelet proteins responsive to water deficit and heat stress to critical physiological processes during flowering is discussed.
摘要：
Selection for yield per se has greatly contributed to yield improvement in many crops. It is expected that selection based on plant traits is more effective in increasing crop yield potential. This study was conducted to compare the effectiveness of trait-based and yield-based selection in increasing rice yield and to determine whether lines with ideotype traits have the potential to express higher yield under optimal crop management conditions. Lines were selected based on plant traits or on grain yield measured in a breeder's replicated yield trial. The main target traits for selection were plant height, leaf and panicle morphology, grain size, total dry weight, and grain-filling percentage. Yield performance of trait-based selection was compared with that of yield-based selection in an agronomic trial with optimum crop management for three seasons. Trait-based selection increased leaf area index and total dry weight but reduced spikelet number per m(2) and harvest index compared with yield-based selection. Consequently, selection based on plant traits did not increase grain yield compared with selection based on yield per se. In one of the three seasons, yield of trait-based selection was significantly lower than that of yield-based selection. Among all tested breeding lines, maximum yield was produced by yield-based selection and minimum yield came from trait-based selection. These results suggest that lines with ideotype traits did not express higher grain yield than lines selected based on yield per se under optimal crop management conditions, and yield-based selection was as effective in increasing rice grain yield as trait-based selection in the late generations of the breeding cycle. (C) 2011 Published by Elsevier B.V.
摘要：
A previous study has identified two types of recombinant variants of Potato virus Y strain NTN (PVYNTN) in China and sequenced the complete genome of the variant PVYNTN-HN2. In this study, the complete genome of isolate PVYNTN-HN1 was fully sequenced and analyzed. The most striking difference between the two variants was the location of recombinant joint three (RJ3). In PVYNTN-HN1, like other typical European-PVYNTN isolates such as PVYNTN-Hun, the RJ3 was located at nucleotide (nt) 9183, namely the 3' proximal end of the CP gene (nt. 8571-9371), thus leading to most (the first 613 nucleotides from the 5' proximal end) of the CP gene (801 bp) with a PVYN origin and PVYN-serotype; whereas in contrast, the RJ3 in PVYNTN-HN2 was located at nt 8572, consequently leading to a CP gene of PVYO origin and PVYO-serotype. The varied genome composition among PVYO, PVYN, PVYN:O, PVYNTN-HN1 and PVYNTN-HN2 made them useful for the investigation of possible roles of gene segment(s) in symptom formation on host plants. When Physalis floridana plants were infected with different PVY isolates, two types of symptoms were induced. PVYN and PVYNTN-HN1 induced mild symptoms (mainly mild mottling) whereas PVYO, PVYN:O and PVYNTN-HN2 induced serve symptoms including leaf and stem necrosis, leaf-drop and stunting. These results, together with a previous study using artificial PVY chimeras, demonstrate that the CP gene, especially the 5' proximal segment (nt 8572-9183), and/or CP likely determine the pathogenicity of PVY in P. floridana.
作者：
Rang, Z. W.;Jagadish, S. V. K.*;Zhou, Q. M.;Craufurd, P. Q.;Heuer, S.
期刊：
Environmental and Experimental Botany,2011年70(1):58-65 ISSN：0098-8472
通讯作者：
Jagadish, S. V. K.
作者机构：
[Heuer, S.; Jagadish, S. V. K.; Rang, Z. W.] Int Rice Res Inst, Manila, Philippines.;[Zhou, Q. M.; Rang, Z. W.] Hunan Agr Univ, Coll Agron, Changsha 410128, Hunan, Peoples R China.;[Craufurd, P. Q.] Int Crops Res Inst Semi Arid Trop, Patancheru 502324, Andhra Pradesh, India.;[Jagadish, S. V. K.] Int Rice Res Inst, DAPO Box 7777, Manila, Philippines.
通讯机构：
[Jagadish, S. V. K.] I;Int Rice Res Inst, DAPO Box 7777, Manila, Philippines.
摘要：
In many hilly regions of Three Gorges Reservoir Area, China, land use types diversity characteristics principally resulted from disafforestation, vegetation breakage, and increasing terraced field and artificial forest. In this paper, we elucidated the soil-land use type, soil-landscape position relationships at slope scale using quantitative methods based on the effects of land use and slope landscape position on the spatial distribution of soil nutrients. Five typical land use types (woodland, paddy field, upland, orchard and fallow) under four landscape positions (upper slope, middle slope, lower slope and foot slope) were chosen for this study. In each slope position, five different land use types were selected to collect soil samples. Two integrated quantitative indexes were developed to perform a comparison for soil quality under different land use and landscape position using principal component analysis (PCA) and multivariate statistical analysis. The results indicated that the soil quality index (SQI) values for forest, paddy, upland, orchard and fallow were 0.77, 0.35, 0.22, 0.38 and 0.53, respectively. These implied that woodland maybe is an optional choice to restore the soil fertility in some regions where soil conditions are suitable for forest secondary succession. The soil degradation index (SDI) was regarded as an integrated indication of soil quality in different slope positions. The positive value showed improvement of the soil quality, whereas negative value indicated deterioration of the soils. The calculated SDI reflected the percent changes in soil properties compared with middle slope position in this study. The SDI values for different slope positions from up to down were -13.3%, 0, -8.6% and 15.52%, respectively. These SDI values were represented by "N"-shaped distributions. SDI showed that foot and middle slope had higher soil quality compared to upper and lower slope. These results indicated that it is important for soil fertility conservation to adjust reasonably land use type in different slope positions, e.g. farmland can be reclaimed in foot slope position.
摘要：
Expression profiles of 12 class A rice heat shock transcription factor genes (OsHsfAs) were analyzed by semi-quantitative reverse transcriptase polymerase chain reaction. The OsHsfA genes exhibited tissue-specific expressions under normal condition. OsHsfA1a, A2d, and A9 were predominantly expressed in young spike. Expression responses of the 12 OsHsfAs under abiotic stresses were analyzed in the shoots of rice seedling. Most OsHsfA genes responded quickly to heat stress except for OsHsfA1a, A3, and A9 which were almost unaffected. In particular, OsHsfA2a expression in response to heat stress was highest among the heat shock factors examined. However, the majority of the increased OsHsfAs expression responses to salt, polyethylene glycol (PEG), and cold treatments primarily occurred during the later stages (3 to 24 h) of stress exposure. Furthermore, most of OsHsfA gene expressions were little affected and only a few (OsHsfA3, A4d, A7, and A9) genes had slow responses to cold treatment. The results indicate that the transcript levels of OsHsfAs during heat stress exposure were distinct from those of plants subjected to salt, PEG, and cold stresses, suggesting that there might be different regulatory networks between heat and non-heat stress.
作者机构：
[Shu, W. S.; Lan, C. Y.; Zhou, M.; Ye, Z. H.; Yang, B.] Sun Yat Sen Zhongshan Univ, State Key Lab Biocontrol, Guangzhou 510275, Guangdong, Peoples R China.;[Shu, W. S.; Lan, C. Y.; Zhou, M.; Ye, Z. H.; Yang, B.] Sun Yat Sen Zhongshan Univ, Sch Life Sci, Guangzhou 510275, Guangdong, Peoples R China.;[Qiu, R. L.] Sun Yat Sen Zhongshan Univ, Sch Sci & Engn, Guangzhou 510275, Guangdong, Peoples R China.;[Qiu, R. L.] Sun Yat Sen Zhongshan Univ, Guangdong Prov Key Lab Environm Pollut Control &, Guangzhou 510275, Guangdong, Peoples R China.;[Jie, Y. C.] Chinese Acad Agr Sci, Inst Bast Fiber Crops, Changsha 410205, Hunan, Peoples R China.
通讯机构：
[Ye, Z. H.] S;Sun Yat Sen Zhongshan Univ, State Key Lab Biocontrol, Guangzhou 510275, Guangdong, Peoples R China.
