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71.
Reinhard W. Neugschwandtner Hans-Peter Kaul 《Archives of Agronomy and Soil Science》2016,62(9):1236-1249
Intercropping is of increasing interest in temperate-arable farming systems. The influence of nitrogen (N) fertilization and sowing ratio on concentrations and uptake of calcium (Ca), potassium (K), magnesium (Mg) and phosphorus (P) by oat and pea was assessed in three substitutive intercrops on a fertile soil in eastern Austria. N decreased Ca in oat grain and increased P in pea grain as well as Ca and Mg in oat residue and Mg and P in pea residue. Intercropping did not affect nutrient concentrations of oat grain, whereas a lower pea share in intercrops increased P in pea grain. In residue, Ca, K and Mg concentrations were higher in oat and Ca and K partly lower in pea with a lower share of each crop. The oat-dominated intercrops could partly achieve a slightly higher total grain nutrient yield than pure stands at no or low N; however, these benefits diminished with a higher pea share and N input. In comparison to pure stands, higher residue nutrient yields were obtained by intercropping in all sowing ratios and fertilization levels. Consequently, oat–pea intercropping can be a strategy for increasing the macronutrient yield of grain and especially of residue for ruminant feeding. 相似文献
72.
37种杀虫剂混剂对稻纵卷叶螟的田间防治效果 总被引:5,自引:1,他引:4
为进一步明确现有杀虫剂对水稻稻纵卷叶螟的效果。2007年,在大田中,以喷雾施药法对37种杀虫剂混配剂进行了防治稻纵卷叶螟的田间试验。结果表明:用药20天后,对稻纵卷叶螟控制效果达90%以上的品种有11种;控制效果达80%~89%有23种;控制效果〈80%的仅3种。可以认为,合理的混配剂,可能是今后控制稻纵卷叶螟为害的最为经济有效品种。 相似文献
73.
Aiming to calculate the true critical parameters of refrigerant mixtures, the Helmholtz free energy stability criterion for thermal systems is adopted to establish a calculation thermodynamic model of the true critical parameters. A novel optimization alg 相似文献
74.
J. Bennewitz T.H.E. Meuwissen 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2010,127(3):171-179
The present study used published quantitative trait loci (QTL) mapping data from three F2 crosses in pigs for 34 meat quality and carcass traits to derive the distribution of additive QTL effects as well as dominance coefficients. Dominance coefficients were calculated as the observed QTL dominance deviation divided by the absolute value of the observed QTL additive effect. The error variance of this ratio was approximated using the delta method. Mixtures of normal distributions (mixtures of normals) were fitted to the dominance coefficient using a modified EM‐algorithm that considered the heterogeneous error variances of the data points. The results suggested clearly to fit one component which means that the dominance coefficients are normally distributed with an estimated mean (standard deviation) of 0.193 (0.312). For the additive effects mixtures of normals and a truncated exponential distribution were fitted. Two components were fitted by the mixtures of normals. The mixtures of normals did not predict enough QTL with small effects compared to the exponential distribution and to literature reports. The estimated rate parameter of the exponential distribution was 5.81 resulting in a mean effect of 0.172. 相似文献
75.
Long‐chain alcohols did not improve predictions of the composition of tall fescue and red clover mixtures over n‐alkanes alone
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N. Vargas Jurado A. E. Tanner S. R. Blevins H. M. McNair R. W. Mayes R. M. Lewis 《Grass and Forage Science》2015,70(3):499-506
Feed intake and diet choice affect production efficiency in livestock. Plant waxes, in particular n‐alkanes, have been used as markers to predict intake and diet preferences. Still, when n‐alkane profiles of plants within mixed swards are similar, they alone may not produce reliable predictions. Including long‐chain alcohols (LCOHs) may help. In this study, the reliability of predicting forage mixtures was assessed using n‐alkanes and LCOH separately and in combination. Reliability was characterized as the regression of observed on predicted fescue proportion in forage mixtures and the Kulczyński similarity index. Two technicians performed extractions of n‐alkanes and LCOHs of pure red clover and ‘Fawn’ tall fescue, and nine mixtures of them. The concentrations of n‐alkanes C27, C29, C31 and C33 and alcohols C26‐OH, C28‐OH and C30‐OH were compared among forage mixtures and between technicians. Technicians were consistent in their measures of n‐alkanes (P > 0·12), but differed in their measures of C26‐OH and C28‐OH (P < 0·002). Longer‐chained compounds were more consistently quantified. Forage delineations were not improved by C26‐OH. With n‐alkanes alone, estimated and actual fescue proportions closely agreed. Including LCOH offered no improvement. Despite variation in measured concentrations between technicians, fescue and red clover mixtures were reliably predicted using n‐alkanes alone. 相似文献
76.
77.
Establishing Kura clover (Trifolium ambiguum) in mixtures with grass species is challenging, because slow growth of clover seedlings results in low competitive ability. This study examined establishment success by altering time of seeding of the grass component to reduce competition with Kura clover seedlings. Two trials, one of Kura clover–meadow bromegrass (Bromus biebersteinii) and the other Kura clover–orchardgrass (Dactylis glomerata) mixtures were planted in Edmonton, Alberta. Grasses were seeded at the same time as the clover, or introduced when the clover reached one true leaf or three true leaves, in the autumn of the planting year or the following spring. Species composition varied significantly between treatments. When sown at the same time, Kura clover contributed 31 and 14% of yield in the establishment year when sown with meadow bromegrass and orchard grass, respectively. Delaying grass sowing until Kura clover had one or three leaves gave a higher percentage of Kura clover compared with planting at the same time. Autumn and spring grass sowing resulted in stands of 78 and 80% clover with meadow bromegrass, and 74 and 67% clover with orchardgrass. Altering the competitive advantage of the grass species to produce a more balanced mixture was successfully achieved by delaying seeding of the grass relative to Kura clover. A long interval before introducing the grass (autumn or following spring), was not successful as established Kura clover seedlings have an increased competitive ability. 相似文献
78.
用深绿木霉T95和球毛壳ND35两种拮抗菌株以及两者的混合菌株对由瓜果腐霉Pa和立枯丝核菌Rs引起的猝倒病和立枯病的防治效果进行了初步研究。平皿对峙结果表明,对瓜果腐霉Pa抑制作用最大的为ND35+T95混合拮抗菌,生长抑制率为73.36%,高于拮抗菌ND35对瓜果腐霉Pa的生长抑制率47.87%。而对立枯丝核菌Rs的拮抗作用三者之间差异不显著。盆栽试验结果表明,在菜豆上ND35+T95混合菌株对猝倒病的防治效果高于单个菌株深绿木霉T95,但在黄瓜、番茄上差异不显著。田间试验结果表明,混合拮抗菌株ND35+T95组合对立枯病和猝倒病的防治效果分别为49.05%和60.37%,均高于单一拮抗菌株深绿木霉T95的防治效果,但与对照化学药剂恶霉灵相比存在一定的差异。 相似文献
79.
The milk-production potential of different sward types was measured in each of the four seasons of the year in a replicated experiment in south-west Victoria, Australia. Dairy cows were offered ad libitum allowances of a 'short-term winter' sward, based on Italian ryegrass (treatment STW), a 'long-term winter' sward, based on a winter-active tall fescue (treatment LTW), a 'long-term summer' sward, based on a summer-active tall fescue (treatment LTS) and a Control sward (perennial ryegrass) in four seasons (days in milk in parentheses): spring (November dairy cows, 124), summer (February, 227), autumn (May, 234) and winter (August, sixty-four). A 'short-term summer' sward, based on chicory and white clover (treatment STS), was also included in summer. There was a significant season × treatment interaction caused by a more gradual decline in milk yield from peak for cows grazing treatment LTS compared to the Control treatment in the transition period from spring to summer. In summer, cows grazing treatment STS produced more milk (1·41 kg fat plus protein per cow d−1 ) than cows grazing all other treatments (0·92 kg per cow d−1 ) because of the superior nutritive value of herbage of pre-grazing pasture and higher apparent dry-matter intakes. Swards based on alternative species to perennial ryegrass are capable of supporting milk production that is at least comparable over an annual cycle. 相似文献
80.
本文通过对杉木连栽多代林地及连栽地营造不同类型混交林后林地的上壤化学性状和土壤生化特性的比较研究,探讨杉木连栽多代的林地营造不同混交林后土壤酶活性及化学性状的变化趋势,土壤酶活性与土壤养分含量之间的相关性。试验结果表明:在杉木连栽多代后营造不同类型混交林,土壤的营养元素含量有显著的增加,以有机质增加最为显著,土壤的生化活性除了个别的酶外,不同类型的混交林显著比多代的杉木纯林高,其中以柳杉×薄姜木为最佳;各种土壤酶活性与土壤化学性状关系密切,单相关系数可达0.3452—0.9745,复相关系数0.8710—0.9745,可用土壤酶活性作为评价杉木连栽林地土壤改良中土壤肥力变化的指标之一;综合土壤酶活性及土壤化学性状进行聚类分析,表明杉木连栽后营造成不同类型的混交林,均能提高土壤肥力,有良好的改土作用,本研究中,以柳杉×薄姜木最为理想。 相似文献