Reduced inter-row distance improves yield and competition against weeds in a semi-dwarf durum wheat variety

Weed and nutrient management in cropping systems of semi-arid areas is a major constraint to cereal yield. Where the use of herbicides is banned or discouraged, the competitive ability of a crop is crucial to reduce weed growth and diffusion. Genotypic differences in the competitive abilities of crops are an important trait to reduce weeds, especially for plant height. However, there is contrasting information about the interactions of other management practices and genotypic traits on wheat yield and competitive ability against weeds and weed growth. The present study investigated yield and quality of durum wheat (Triticum durum Desf.) and weed growth and composition for two wheat cultivars with contrasting competitive abilities against weeds. Wheat was grown under three spatial arrangements (5-cm, 15-cm, 25-cm inter-row distance) and three sowing densities, and broadleaf weeds were either removed or not. The sowing rate did not affect the yield of these wheat cultivars or the weed growth. Reduced inter-row distance dramatically reduced weed biomass for both wheat cultivars, and increased wheat yield and nitrogen uptake in the low-competitive, high-yielding, semi-dwarf cv. ‘PR22D89’, when both weed free and with weeds. These results have direct implications for weed and nutrient management in low-input and organic cropping systems.     

Enhancement in Nutrient Accumulation and Growth of Oil Palm Seedlings Caused by PGPR Under Field Nursery Conditions

Abstract

Plant growth promoting rhizobacteria (PGPR) (e.g., Azospirillum and Bacillus spp.) have been reported to enhance growth and fix N₂ with several nonleguminous crops. These rhizobacteria have the potential to be applied to oil palm seedlings and, consequently, reduce the cost of nitrogenous fertilizer. The rhizobacteria are also known as a bioenhancer for the ability to increase root growth and enhanced water and nutrient absorption by the host plants. An experiment was carried out in the field nursery station, Federal Land Development Authorities (FELDA), Bukit Mendi, Pahang, Malaysia, to observe the effects of PGPR inoculation on enhanced nutrient accumulation and plant growth (tops and roots) of oil palm seedlings under field nursery conditions. The inoculation process showed positive response in enhancing higher accumulation of nitrogen (N), phosphorus (P), and potassium (K) in the plant tissues, enhanced root dry weight and top growth (dry matter and leaf chlorophyll content) of the host plants under field nursery conditions.     

Application of the Soil and Water Assessment Tool (SWAT) to predict the impact of alternative management practices on water quality and quantity

Alternative land management practices such as conservation or no-tillage, contour farming, terraces, and buffer strips are increasingly used to reduce nonpoint source and water pollution resulting from agricultural activities. Models are useful tools to investigate effects of such management practice alternatives on the watershed level. However, there is a lack of knowledge about the sensitivity of such models to parameters used to represent these conservation practices. Knowledge about the sensitivity to these parameters would help models better simulate the effects of land management. Hence, this paper presents in the first step a sensitivity analysis for conservation management parameters (specifically tillage depth, mechanical soil mixing efficiency, biological soil mixing efficiency, curve number, Manning's roughness coefficient for overland flow, USLE support practice factor, and filter strip width) in the Soil and Water Assessment Tool (SWAT). With this analysis we aimed to improve model parameterisation and calibration efficiency. In contrast to less sensitive parameters such as tillage depth and mixing efficiency we parameterised sensitive parameters such as curve number values in detail.In the second step the analysis consisted of varying management practices (conventional tillage, conservation tillage, and no-tillage) for different crops (spring barley, winter barley, and sugar beet) and varying operation dates. Results showed that the model is very sensitive to applied crop rotations and in some cases even to small variations of management practices. But the different settings do not have the same sensitivity. Duration of vegetation period and soil cover over time was most sensitive followed by soil cover characteristics of applied crops.     

菊花无土栽培技术研究

采用无土栽培技术，对９０余个品种的２６０余盆菊花进行了营养液配方及基质、栽培方式的试验研究，认为在太原市水质及气候条件下，菊花的无土栽培方式以虹吸式、半液式为宜，营养液配方采用３号配方、１号配方或朱士吾提出的通用配方略加调整。     

一品红无土栽培试验

用5种基质和6种不同的营养液,对一品红生长的影响进行了对比试验,结果表明：以蛭石和珍珠岩组成的基质A,搭配Y2和Y3营养液配方的处理效果较佳。     

Yields nutrient intake and soil fertilizing in 40 years fertilizer trials

The set of twenty long‐term field nutrition trials starting from 1957 at five sites. The sites differed by their altitude (from 180 m to 620 m) with average daily temperatures (from 6,8°C m to 9°C m) and soil type (from chernozem to brown podsolic soil) Provided mainly the following results:

? The geonomic division to the fertile sugarbeet region and less fertile potato region did not strictly differentiate the influence of fertilizer and climatic effects to the crop yields.

? The effect of fertilizing was dependent on the nutrient content and on the conditions of releasing and binding of the nutrients in soil.

? The precipitation regime has a strong influence on the effect of the nitrogen escalated doses.

? The facts concerning the nutrient intake are very precious knowledge. These facts have not been examined yet during the long‐term trials.

? The site effect, particularly its climatic conditions, on the nutrient intake is often more obvious compared to the fertilizing effect.

? Very interesting impulses for further research monitoring during the long‐term trials was contributed by “mapping”; of soil capacity to provide nutrients to plants at various sites and under different climate.     

竹林养分循环规律研究：Ⅲ.毛竹纯林竹秆流及其养分输入

在我国毛竹主要产区浙江省安吉县灵峰寺林场试验林的三个区组中，根据立竹直径分布规律确定样竹处理数后，随机布置总共30套秆流收集装置，持续观察21个月，共获91次秆流水。测定每次秆流水量并分析其N、P、K、Ca、Mg含量以研究毛竹林内秆流的变化动态及其养分输入。结果表明：秆流水中不含Ca，其它四元素的年输入量分别为N-1．8557，P-0．0072，K-0.7849，Mg-0.1569，Kg.ha－1；年秆流量为年降水量的12．5％，无论次、月秆流量与相应降水量均为紧密线性相关，但与立竹粗度为显著非线性相关；其它因子，如：立竹所处的坡位、坡向，竹林密度，钩梢强度，立竹分布状况，植株个体表面结构特征等，亦直接或间接地影响着竹秆流的产生和大小。     

Introduced slugs and indigenous caterpillars as facilitators of carbon and nutrient mineralisation on a sub-Antarctic island

Indigenous soil macroinvertebrates (moth larvae, weevil larvae, earthworms) are cardinal agents of nutrient release from litter on sub-Antarctic Marion Island (47°S, 38°′E). Their populations are threatened through predation by introduced house mice, which do not prey on an introduced slug Deroceras panormitanum. A microcosm study was carried out to explore whether slugs affect rates of carbon and inorganic nutrient mineralisation from plant litter differently to an indigenous caterpillar (larva of a flightless moth Pringelophaga marioni). Caterpillars stimulated N, Ca, Mg and K mineralisation from plant litter two to five times more than slugs did, whereas the two invertebrate types stimulated C and P mineralisation to the same degree. Consequently, ratios of C:N and N:P released from the litter were different for slugs and caterpillars. Such differences might affect peat nutrient quality and ultimately the peat accumulation-decomposition balance, an important driver of ecological succession. This suggests that slugs cannot simply replace caterpillars without consequences for ecosystem structure and functioning on the island.     

胡椒园土壤养分相关性研究

对海南典型胡椒园0～40 cm土层养分的相关性的研究结果表明：土壤pH和全N属弱变异，其余养分均属高变异；除全N和交换性Ca外，其余养分的中心趋向分布为非标准正态分布；土壤有机质与碱解N、速效K、有效Cu、有效S呈极显著正相关，与交换性Ca呈显著正相关；pH与碱解N、交换性Ca、有效Mn、有效Cu呈极显著正相关，与速效K呈显著正相关。     

营养液对毛竹叶片效应的研究 Ⅱ.营养液对叶片光合性状影响

在毛竹丰产林中 ,设置 4块标准地 ,1 996年 1 1月注射毛竹营养液 ,1 997年夏在各注射和未注射营养液的标准地中取 1 992～ 1 997年生毛竹枝叶测定光合速率、光呼吸、暗呼吸、CO2 补偿点、光补偿点等光合性状。结果表明 ,施用毛竹营养液后叶质重、叶绿素含量明显提高 ,净光合速率增大 ,暗呼吸有所提高 ,光呼吸速率减小 ,CO2 补偿点和光补偿点明显下降 ,这些指标的改变有利于提高光合作用、增加有机质积累 ,有利于培养高产稳产竹林。