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81.
82.
从坚持统筹协调以强化现代农业规划引领、坚持开放兼容以推进一二三产业融合、坚持绿色安全以加快农业供给侧改革、坚持改革创新以保障农业可持续发展、坚持合作共享以提升农业产业化经营水平5个方面阐述加快推进江门市的农业现代化建设,旨在将江门市建设成产出高效、产品安全、资源节约、环境友好的现代农业强市。 相似文献
83.
The temperature-dependent population growth potential of Phenacoccus solenopsis Tinsley, a highly polyphagous and invasive mealybug species, was studied on sprouted potatoes under laboratory conditions at six constant temperatures (15–40 °C). Several non-linear equations were fitted to the obtained data to model temperature-dependent population growth and species life history. The established equations for each life age/stage of the species were compiled to obtain an overall temperature-dependent phenology model. The life table parameters of P. solenopsis were estimated using stochastic simulation centred on a rate summation and cohort up-dating approach. The theoretical lower development threshold temperatures estimated using linear regressions applied to mean development rates were 11.2, 8.9, 9.8 and 12.7 °C, and the thermal constants for development were 93.7, 129.8, 97.1 and 100.0 degree days (DD) for nymph 1, nymph 2, nymph 3 and male pupa stages, respectively. The developed phenology model predicted temperatures between 25 and 35 °C as the favourable range for P. solenopsis development, survival and reproduction. P. solenopsis population attained a maximum net reproductive rate (107–108 females/female/generation) and total fecundity (216.6–226.5 individuals/female/generation) at temperatures between 25 and 30 °C. Mean length of generations decreased from 75.6 days at 15 °C to 21 days at 40 °C. The maximum finite rate of increase (1.12–1.16 females/female/day) and shortest doubling time (4.3–6.1 days) were also observed at temperatures between 25 and 35 °C. The simulation of phenology model at fluctuating temperatures indicated that P. solenopsis populations might potentially increase with a finite rate of 1.06 females/female/day with an average generation time of 58.7 days and a doubling time of 12.1 days. The obtained life table parameters were reasonably similar when compared with literature data. The present model can be simulated spatially for estimating the pest risk and undertaking agro-ecoregion specific pest management strategies. 相似文献
84.
本文就“森林衰退病”(Forest decline)理论的概念、意义,森林衰退病病原,“衰退病”(Decline,Dicline disease)模式,以及诱发因素(Predisposing factors)、激化因素(Inciting factors)和促进因素(Contributing factors)之间的相互关系作了综述介绍,并看重强调了运用这一新的植物病理学理论,认识和指导我国林业及热作生产的重要现实意义。 相似文献
85.
H.-P. Piepho 《Journal of Agronomy and Crop Science》1998,180(4):193-213
The stability of yield is an important characteristic to be considered when judging the value of a cropping system relative to others. In the context of agricultural research, the analysis of yield stability has been largely confined to multienvironment trials of crop cultivars. This review emphasizes that methods for comparing the stability of cultivars can also be used for comparing different agronomic treatments in general, of which cultivars are but a special case. Throughout the paper, different agronomic treatments are referred to as cropping systems. Some of the methods useful for stability analysis of cropping systems are discussed and a brief review of applications of these methods is given. The paper puts different stability measures into a unifying mixed model perspective. 相似文献
86.
A. Gallais 《Euphytica》1988,39(2):95-104
Summary To discuss the utilisation of heterosis in plant breeding it is necessary to consider its genetic basis. In cross fertilized plants in which the phenomenon of heterosis is very important, such as maize, it appears that a great part can be explained by the mutation load. However in both autogamous or allogamous plants it is difficult to exclude a role of marginal overdominance which could justify hybrid variety production.To know in a relatively short time whether it will be better to develop lines or hybrids it is necessary to know the parameters (mean and variance) of the distribution of all varieties of a given type which can be derived from the breeding population. A numerical application allows the determination of the situations where the best single crosses will be better than the best lines. With some approximate values of the necessary parameters, the case of grain yield in maize and in wheat is briefly discussed.To develop lines or hybrids, a general strategy is given. Its main axis is population improvement which has to be adapted to the type of varieties to develop. It is shown that according to the situation the type of varieties to develop can change with time: single crosses can be more justified at the beginning and lines can be justified later if all heterosis were fixable. To develop hybrids the best scheme is reciprocal recurrent selection with half-sib or full-sib progenies followed by pedigree reciprocal selection initiated by full-sib progeny tests. With this strategy there is no problem of the prediction of hybrid performances. However it seems possible to develop some predictors of heterosis or of specific combining ability between two lines using some criteria of genetic distances. Preliminary results with distances computed from the behaviour of lines in a two-tester top cross design appears very stimulating.Communication given at the206th meeting of teh Genetical Society of Grain Britain 相似文献
87.
Lauriane Rouan Alain Audebert Delphine Luquet Sandrine Roques Audrey Dardou Eric Gozé 《Plant Production Science》2018,21(3):256-265
Air temperature is one of the most critical climatic factors controlling rice growth, development, and production in current and future climatic scenarii predicting increasingly frequent situations of extreme and/or fluctuating temperatures. With its large spectrum of geographical origins and cropping areas, one can credit tropical japonica rice subspecies of a probable genetic diversity of its response to air temperature, which is of major interest for the breeding of better adapted rice varieties. A panel of 195 rice accessions (175 japonica plus 20 reference cultivars) was studied in controlled environment to estimate cardinal (base, optimum, and maximum) temperatures based on the monitoring of the elongation rate (LERmax) of the sixth leaf on the main stem in response to six fixed thermal treatments ranging from 16 to 35 °C. A dedicated statistical framework was elaborated for estimating LERmax, cardinal temperature and related uncertainties. Developed statistical framework enhanced the precision of cardinal temperatures estimated compared to previously reported methods, especially for base temperature. Maximum temperature was trickier to estimate and will require further studies. A significant genotypic variability for base and optimal temperature was pointed out, suggesting tropical japonica subspecies represents a relevant genetic pool to breed for rice genotypes adapted to various thermal situations. These results also suggested that using genotype-dependent cardinal temperature values should enhance the way crop growth models account for genotype?×?environment interactions hence their predictive value in current and future climatic conditions. 相似文献
88.
S. Orlandi E. Nucera E. Mosimann G. D'Adda D. Garzoli M. Bertossa M. Lonati G. Lombardi 《Grass and Forage Science》2017,72(1):154-162
Invasive grasses (especially Setaria pumila (Poir.) Roem. et Schult) increasingly threaten meadows and pastures as a consequence of human impact and climate change. We conducted a study in 2012 and in 2013 to better understand the growing cycle and the influence of S. pumila on forage quality of lowland meadows. We observed a rapid increase of S. pumila presence and phytomass on the southern side of the Alps across the growing season. We measured (i) above‐ground phytomass, with a modified Corral‐Fenlon method; (ii) botanical composition using the linear point quadrat method; and (iii) grassland chemical composition by NIRs (near‐infrared spectroscopy) analyses. To test the hypothesis that S. pumila summer growth is related to specific climatic conditions, meteorological data (temperature, precipitation and evapotranspiration) were collected from meteorological stations near the study sites. Total phytomass was sorted into S. pumila and other species. We used a generalized linear mixed models (GLMM) and found the abundance of S. pumila to be inversely correlated with rainfall and the presence of other species, but positively correlated with temperature increase. The increase of S. pumila above‐ground phytomass production was linked to a reduction of forage quality. 相似文献
89.
郭杰光 《农业图书情报学刊》2007,19(3):168-171
通过对该馆自动化开架借阅藏书发展工作中投入产出效益的研究,以进一步深化藏书发展工作,提高经费使用效益。 相似文献
90.
李名扬 《西南大学学报(自然科学版)》1987,(2)
川楝(Melia toosendan Sieb.et Zucc.)花药具四个小孢子囊,壁由六层细胞构成,表皮层在花药成熟时呈乳头状突起,宿存于”纤维层”之外;分泌型绒毡层具2—4核;小孢子母细胞为同时型胞质分裂;四分体多为四面体型,少数为十字交叉型;有的四分体中有退化小孢子产生;花粉粒释放时为二细胞型,具四条沟,有部分败育。胚珠倒生,具双珠被和厚珠心;大孢子孢原为皮下单细胞;珠孔仅由内珠被形成;珠被属表皮性起源;线型的大孢子四分体中仅合点端之一为功能大孢子;雌配子体发育为蓼型;三个反足细胞在形成后不久即退化消失。川楝配子体的发育与同属的楝有一定的差异。 相似文献