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991.
Raquel Sánchez-Pérez Encarnación Ortega Henri Duval Pedro Martínez-Gómez Federico Dicenta 《Euphytica》2007,155(3):381-391
The inheritance of 16 important agronomic traits and its relationship were studied for four years in a population of 167 almond
[P. dulcis (Mill.) D.A. Webb] seedlings obtained from a cross between the French selection ‘R1000’ (‘Tardy Nonpareil’ × ‘Tuono’) and
the Spanish cultivar ‘Desmayo Largueta’. For some traits (blooming and leafing date) descendants segregated between the value
of both progenitors, meanwhile for others the mean of the offspring was lower (bloom density, productivity and ripening date)
or higher (in-shell/kernel ratio and double kernels). As expected, kernel bitterness and self-incompatibility behaved as monogenic
traits. Some important correlations between traits were detected. The implications of the transmission and the correlation
of these traits in the breeding programmes are discussed. 相似文献
992.
为确定合理的包膜尿素用量以指导黄瓜育苗施肥,采用生产中常用的草炭:蛭石(2:1)为育苗基质,研究了包膜尿素不同用量对黄瓜幼苗生长、养分吸收及氮平衡的影响。结果表明:包膜尿素用量在125~375 mg N/株的情况下,可协调黄瓜幼苗地上部和地下部的生长,促进幼苗对磷、钾的吸收;移栽时,基质中的氮素残留总量90.5~250.3 mg N/株,其中,残留的包膜氮素占75.4%~82.3%,可实现带肥移栽;育苗期间可产生31.9~121.5 mg N/钵的氮素表观损失。 相似文献
993.
本研究以半年生翠云草盆栽为试验材料,研究不同遮荫处理对翠云草叶色变化的影响。试验设置全光照R0(透光率100%NS)、一层遮荫R1(38%NS)、二层遮荫R2(20%NS)、三层遮荫R3(16%NS)和四层遮荫R4(10%NS)共5个处理。处理3个月后,比较叶片中叶绿素a、叶绿素b、叶绿素a+b、叶绿素a/b、类胡萝卜素、花色素苷、苯丙氨酸解氨酶及可溶性糖含量变化。结果显示,叶绿素含量在3层遮荫处理下最高,叶片表现出特殊的蓝绿色;全光照下,叶绿素含量和花色素苷含量均最低,而类胡萝卜素含量最高,说明叶片受到强光胁迫,是类胡萝卜素而不是花色素苷取代了那部分被破坏的叶绿素,因此叶片表现出红色。方差分析表明,不同遮荫处理对翠云草叶片中叶绿素含量影响极显著,对花色素苷含量影响显著,而对类胡萝卜素含量影响不显著。掌握翠云草叶色在不同遮荫条件下的变化规律,有助于在园林中根据景观需要进行合理配置,创造别具特色的园林植物景观。 相似文献
994.
Purpose
The aim of the present study was to investigate the effects of visitors’ activities on soil properties in parks of Tel Aviv-Jaffa city, Israel.Materials and methods
The city was divided into three geographical regions: south, central, and north. This division reflects the course of development of the city from south to north and encompasses various socioeconomic levels of residents. In each region, 9–15 parks were randomly chosen and classified into three groups according to their size (in m2): 2?×?103 to 10?×?103, 11?×?103 to 20?×?103, and 21?×?103 to 50?×?103. In each park soil, 0–2 cm of depth layer was sampled in areas under various levels of visitor pressure from July to August 2011, and organic matter, electrical conductivity, and sodium and chlorine contents were determined. Lawns and path and picnic areas represented low and high visitor pressure, respectively. Observations were conducted to characterize the various land uses of the parks and to estimate the numbers of visitors. Also, questionnaires were used at selected parks to assess visitors’ motivations or reasons for visiting the parks.Results and discussion
Socioeconomic indicators, such as the number of residents, the apartment areas, and the percentages of family households, differed among the regions. Soil properties differed between the areas of high and low visitor pressure: they were influenced by type of human activity, size of the park, and number of visitors.Conclusions
Soil properties are affected by variations in the intensity of park use by visitors and by the type of activities enjoyed by these visitors, both of which depend on the socioeconomic status of the park area.995.
Christine Stark Leo M. Condron Alison Stewart Hong J. Di Maureen O’Callaghan 《Biology and Fertility of Soils》2007,43(5):531-540
Because soil biota is influenced by a number of factors, including land use and management techniques, changing management
practices could have significant effects on the soil microbial properties and processes. An experiment was conducted to investigate
differences in soil microbiological properties caused by long- and short-term management practices. Intact monolith lysimeters
(0.2 m2 surface area) were taken from two sites of the same soil type that had been under long-term organic or conventional crop
management and were then subjected to the same 2.5-year crop rotation [winter barley (Hordeum vulgare L.), maize (Zea mais L.), lupin (Lupinus angustifolius L.), and rape (Brassica napus L. ssp. oleifera)] and two fertilizer regimes (following common organic and conventional practices). Soil samples were taken after crop harvest
and analyzed for microbial biomass C and N, microbial activity (fluorescein diacetate hydrolysis, arginine deaminase activity,
and dehydrogenase activity), and total C and N. The incorporation of the green manure stimulated growth and activity of the
microbial communities in soils of both management histories. Soil microbial properties did not show any differences between
organically and conventionally fertilized soils, indicating that crop rotation and plant type had a larger influence on the
microbial biomass and enzyme activities than fertilization. Initial differences in microbial biomass declined, while the effects
of farm management history were still evident in enzyme activities and total C and N. Links between enzyme activities and
microbial biomass C varied depending on treatment, indicating differences in microbial community composition. 相似文献
996.
Elizabeth Rice 《Genetic Resources and Crop Evolution》2007,54(4):701-713
Using survey data from Jala, Mexico, this case-study evaluates in situ maize conservation of the variety ‘Jala’ (Zea mays L.). Though historically ‘Jala’ was the dominant variety grown in the valley of Jala, today less than 20% of farmers grow
it on only 5% of the maize area. Younger growers of the ‘Jala’ variety specialize in it, growing relatively large amounts
for niche markets. Older, diversified farmers grow small areas for household use and to compete in a local contest. Conservation
of the ‘Jala’ variety has been heavily influenced by shifting ideal concepts of maize, as determined by market and consumption
demands and by a contest designed to promote in situ conservation. The current move away from nationalized purchasing may
favor ‘Jala’s’ continued conservation. 相似文献
997.
Background and Objectives
Soil nitrate nitrogen (NO3 −-N) accumulation is related closely to NO3 − leaching, which is an important issue in groundwater pollution, especially in intensive agricultural areas with saline soils where volumes of water are used in irrigation to avoid salt accumulation in the root zone. However, in the saline environment in Hai River Basin, China, the importance of detailed research into NO3 −-N distribution in the root zone has not been adequately recognized. Considering the impacts of eco-environmental system N and crop production, the present study aimed at contributing to an understanding of the effects of N application rate on soil NO3 −-N distribution, NO3 −-N residue, N loss, and maize (Zea mays L.) yield in this region. 相似文献998.
Joshua M. Tebbs Melinda H. McCann 《Journal of Agricultural, Biological & Environmental Statistics》2007,12(4):534-551
Insect-vectored plant diseases impact the agricultural community each year by affecting the economic value, the quantity,
and the quality of crops. Controlling the spread of disease is an important area in risk assessment, and understanding the
dynamics of vector populations helps researchers to develop effective treatments. In this article, we consider an experimental
design commonly used by researchers who study plant disease and examine large-sample, likelihood-based hypothesis tests that
can be used to characterize disease-transmission behavior in a stratified population. Small-sample size and power results
along with design considerations are provided. We illustrate our testing procedures using two real data examples and provide
recommendations for plant-disease researchers in the field. 相似文献
999.
Abrie J. van der Merwe Albertus L. Pretorius 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(3):328-343
This article applies Bayesian nonparametric techniques of analysis to the mixed linear model. The distribution of the random
effects is specific as a nonparametric prior. A Dirichlet process prior is specified on the space of prior distributions.
A modified Dirichlet process is described and applied using a Gibbs sampler. The approach is demonstrated in an investigation
of the changes over time of packed cell volume in two breeds of cattle. 相似文献
1000.
Anthropogenic N-deposition represents a significant input of N into semi-arid chaparral and coastal sage scrub (CSS) shrublands
of southern California. High levels of atmospheric N deposition have the potential to increase soil C and N mineralization,
and we hypothesize that semi-arid shrubland soil exposed to long-term (decades) high N deposition will have significantly
higher C and N mineralization potentials. This hypothesis was tested in a laboratory incubation where the inorganic N (NH4+NO3) and CO2 production of soils maintained at a constant temperature of 25°C and a soil moisture of 0.25 g H2O/g (65% water-filled pore space) were sampled sequentially over a 50-week period. The temporal trend in cumulative C and
N mineralization was well described by a first- and zero-order model, respectively. Long-term atmospheric N deposition significantly
increased potential N mineralization but not C mineralization, and both the rate and total N mineralization were significantly
positively correlated with the surface (0–10 cm) soil δ
15N natural abundance and negatively correlated with the surface soil C:N ratio. While the incubation techniques used here do
not provide realistic estimates of in situ C or N mineralization, these assays indicate that atmospheric N deposition has
significantly altered ecosystem N storage and cycling. 相似文献