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721.
基于中国农业CGE模型的耕地政策对粮食安全影响研究 总被引:3,自引:4,他引:3
通过构建农业一般均衡模型(CGE),本研究分析了耕地面积减少条件下的粮食安全问题。模拟结果显示,粮食耕地面积减少将导致土地租金、物价指数、GDP价格指数、投资价格指数、出口价格指数增长,导致投资、资本和实质GDP减少,直接影响就业、实际工资、名义工资、家庭可支配收入,家庭消费和政府消费缩减。人民币升值影响出口、关税收入减少,净出口对GDP贡献减少,国家宏观经济形势变坏。因此,在保障粮食安全政策中,必须坚决维护1.2亿hm2耕地红线不动摇,确保国家粮食安全。 相似文献
722.
Alireza Pouyesh Mahmoud Lotfi Hossein Ramshini Ezzat Karami Aliasghar Shamsitabar Elahe Armiyoun 《Plant Breeding》2017,136(4):569-577
The purpose of this research was to evaluate the combining ability of six local Iranian and one imported cantaloupe cultivar. Heritability of traits was estimated using a half‐diallel mating design. Seven parents and their crosses were evaluated in 2013 and 2014. The greatest general combining ability (GCA) for yield and fruit number was for “Rish‐baba” (0.53 kg/plant and 0.3, respectively). The cultivar “Ananasi” had the highest GCA for fruit weight and soluble solids content (SSC) (0.088 kg and 1.4, respectively). “Ananasi” presented the highest GCA values for fruit firmness, chlorophyll a and b and carotenoid content, as well as the highest total chlorophyll content. The cross Garmak × Rish‐baba showed the highest specific combining ability (SCA) for yield with heterosis value of 99%. High heritability estimates for SSC (0.52), flesh thickness (0.61) and concentration of chlorophyll a (0.7) were obtained. Although there were significant SCAs for yield, the parents are suggested to be improved prior to hybrid development. The parent “Ananasi” appears to be a suitable donor in breeding programmes. 相似文献
723.
Markus Bestfleisch Jens Möhring Magda‐Viola Hanke Andreas Peil Henryk Flachowsky 《Plant Breeding》2014,133(1):115-120
The extension of the ripening season in open field production is of high economic interest for strawberry growers. Therefore, targeted breeding for extreme early or late ripening cultivars with high yield potential is of particular interest. Thirteen strawberry cultivars were crossed in a reciprocal way without selfing, and the 144 resulting F1 populations were evaluated in a field trial over a period of two consecutive years. The data were analysed using a mixed‐model approach adapted for diallel crossing designs using SAS 9.3. The variability in the crossing approach is mainly based on the general combining ability (GCA) of the cultivars (additive effects). Specific and reciprocal combining abilities (non‐additive effects) appear less important. The highest GCAs for the trait Marketable Yield were found for the cultivars ‘Polka’ and ‘Yamaska’. The trait Earliness is bilateral with significantly low GCAs for early ripening in ‘Clery’ and ‘Daroyal’ and significantly high GCAs for late ripening in ‘Yamaska’ and ‘Florence’. Crosses with these cultivars are likely to deliver populations with both high yield and an extended ripening period. 相似文献
724.
为了科学地管理和实施土地利用总体规划成果,实现土地资源管理信息化,笔者主要探索基于MapGIS平台下,如何利用土地利用现状数据库和土地利用总体规划成果,建立县乡土地利用总体规划数据库,运用系统分析与流程图法,系统阐述了数据库建立的总体思路、目标、技术路线,解决了在数据库建立过程中规划要素层添加,建立了数据库区文件、线文件以及点文件的属性结构,提出了属性数据的输入方法,并着重对图斑面积量算方法进行描述。结果表明,在MapGIS软件平台下,运用土地利用现状数据库和土地利用总体规划成果可以建立规划数据库。 相似文献
725.
Jochen C. Reif Yusheng Zhao Tobias Würschum Manje Gowda Volker Hahn 《Plant Breeding》2013,132(1):107-114
Predicting single‐cross performance is of high importance to improve the efficiency of sunflower (Helianthus annuus L.) hybrid breeding programmes. We used experimental data from inter‐ and intragroup sunflower hybrids and their parental lines adapted to Central Europe to (i) study the genetic diversity and combining ability and (ii) examine the accuracy to predict hybrid performance based on phenotypic and genomic data. We evaluated 133 intragroup and 104 intergroup hybrids with their parental lines in replicated trials at four environments for grain yield, oil yield and oil content. Furthermore, the parental lines were fingerprinted with 572 AFLP markers. Variance due to specific combining ability was comparable for intergroup and intragroup crosses. This suggested a lack of clearly defined heterotic groups for the sample of studied sunflower lines. Prediction accuracy of hybrid performance based on general combining ability effects was high and could not be increased using genomic selection approaches. For situations where no information on GCA effects of parental lines was available, hybrid prediction based on genomic selection methods was accurate for groups of related lines. For groups of unrelated lines, however, we observed a strong decrease in the prediction accuracy. This suggests that prediction of hybrid performance for crosses based on genetically distant parents remains challenging. 相似文献
726.
Francis Kwame Padi Paul Adu‐Gyamfi Abraham Akpertey Alfred Arthur Atta Ofori 《Plant Breeding》2013,132(2):229-236
High seedling mortality during the establishment phase of cocoa has become a critical constraint to sustainable cocoa farming. The objective of this study was to develop varieties with higher seedling survival compared with cultivars currently recommended for planting in denuded regions. Thirty‐seven families composed into two sets of 18 (families from recommended clones) and 19 (families from recently introduced clones) were evaluated for field survival under full sunlight and dry weather conditions. Families differed significantly for vigour (increase in trunk cross‐sectional area, TCSA) and percentage of survived seedlings by the end of the dry weather conditions. Survival and vigour were significantly correlated in only one set of families. The contribution of general combining ability (GCA) to seedling survival was low to moderate. An Amelonado clone and clones from the Iquitos genetic group had negative GCA estimates for both increase in TCSA and survival. Clones of Scavina origin had the most positive contribution to survival. The key outcome of the study was that cocoa families with higher establishment success can be obtained from the currently available germplasm. 相似文献
727.
728.
F. Calle J. C. Perez W. Gaitán N. Morante H. Ceballos G. Llano E. Alvarez 《Euphytica》2005,144(1-2):177-186
There is a limited knowledge on the inheritance of traits with agronomic relevance in cassava. A diallel study among 10 parental
clones was conducted in the acid-soils environment in the eastern savannas of Colombia. Thirty clones were obtained for each
F1 cross. Each clone was represented by six plants, which were distributed in three replications at two locations. Therefore,
the same 30 genotypes of each F1 cross were planted in the three replications at the two locations. Analysis of variance suggested
significant effects for five of the six variables analyzed (harvest index, dry matter content, height of first branching,
reaction to super elongation disease, and plant type scores). Fresh root yield showed strong genotype × environment interaction
and differences between crosses reached statistical significance in only one of the two environments analyzed. General and
specific combining ability effects and their interaction with the environment were significant for most of the variables as
well. Results suggested that dominance plays an important role particularly in the cases of fresh root yield and harvest index. 相似文献
729.
730.
作物根系层土壤水分模拟的经验-机理模型 总被引:1,自引:0,他引:1
To predict soil water variation in the crop root zone,a general exponential recession (GER) model was developed to depict the recession process of soil water storage.Incorporating the GER model into the mass balance model for soil water,a GER-based physicoempirical (PE-GER) model was proposed for simulating soil water variation in the crop root zone.The PE-GER model was calibrated and validated with experimental data of winter wheat in North China.Simulation results agreed well with the field experiment results,as well as were consistent with the simulation results from a more thoroughly developed soil water balance model which required more detailed parameters and inputs.Compared with a previously developed simple exponential recession (SER) based physicoempirical (PE-SER) model,PE-GER was more suitable for application in a broad range of soil texture,from light soil to heavy soil.Practical application of PE-GER showed that PE-GER could provide a convenient way to simulate and predict the variation of soil water storage in the crop root zone,especially in case of insufficient data for conceptual or hydrodynamic models. 相似文献