排序方式： 共有25条查询结果，搜索用时 31 毫秒
1.
Ilyas Siddique Caroline Gutjahr Gamini Seneviratne Broder Breckling Sudheera W. Ranwala Ian J. Alexander 《Biology and Fertility of Soils》2007,44(1):163-170
Topsoil properties were determined in forest gardens established about 20 years ago on eroded grassland soils (abandoned tea
lands) in the wet zone of the Sri Lankan highlands. They were compared with adjacent, eroded grasslands (abandoned tea lands)
on strongly weathered soils vs soils at earlier stages of pedogenic development in a two-way analysis of variance. Soil pH
in forest gardens was, on average, 6.1, nearly one unit higher than in the adjacent grasslands. In the garden soils, the cation
exchange capacity (CEC measured at pH 4.8) was nearly double, exchangeable calcium concentrations five times and exchangeable
magnesium three times as high as in the grasslands soils. Total soil N content was found to be nearly 40% higher in the gardens.
Topsoil gravel contents in the gardens were less than half as high as in the grasslands. The increases in exchangeable bases
and N in gardens, relative to grasslands, were attributed to increased nutrient retention and acquisition. Higher retention
was partly due to the higher CECpH4.8, and probably to reduced erosion and increased, continuous fine root density in the garden topsoils. Higher field CEC in
gardens was likely to result from generally higher C contents and from the reversal of acidification, presumably caused by
base accumulation and decomposition processes. Our results suggest that forest garden establishment on degraded grasslands
can lead to accumulation of mobile nutrients in the topsoil, probably due to increased nutrient retention, subsoil uptake
and litter input exceeding nutrient uptake by the standing biomass. 相似文献
2.
Shahid Iqbal Awan Muhammad Shahzad Ahmed Jehanzeb Farooq Syed Dilnawaz Ahmad Muhammad Ilyas Asad Hussain Shah Muhammad Fareed Khan Sardar Ali Lutful Hasan 《Frontiers of Agriculture in China》2011,5(4):486-496
An experiment was conducted to access the genetic variability among early vigour and quantitative traits under limited moisture
in F2 generation of a 5 × 5 diallel cross of bread wheat. The results indicated that there was significant genotypic variation
among the genotypes. Additive dominance model revealed full fitness of the data for RL, DSW, FRW, DRW, spike length, and 1000-grain
weight but was partially fit for SL, FSW, R/S, tillers per seedling, plant height, tillers per plant, spikelets per spike,
and grain yield per plant. The partially adequate models for these plant characters might be due to the presence of non-allelic
interaction, linkage, and non-independent distribution of the genes in the parents. Additive genes coupled with moderate to
high narrow sense heritability were involved in the heritage of all the traits, which indicated a higher scope of selection
in early generations. 相似文献
3.
Miray?Arli-SokmenEmail author Ilyas?Deligoz Nazli?Dide?Kutluk-Yilmaz 《European journal of plant pathology / European Foundation for Plant Pathology》2016,144(1):1-13
Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus (BCMNV) are well-known legume-infecting potyviruses. The incidences of BCMV and BCMNV infections were determined by ELISA in 367 seed and leaf samples which were collected in 15 common bean-growing provinces of Turkey. Of the samples tested, 67 (18.2 %) occurred to be infected with BCMV, however only 5 (1.4 %) were infected with BCMNV. A total of 45 ELISA-positive samples were selected from single-virus infected ones to determine BCMV and BCMNV pathogenicity groups (PGs) by using a set of bean cultivars that contain different combinations of resistance genes. Some BCMV populations exhibiting unusual pathogenicity were identified. One of them, named TR-180, was found to overcome resistance conferred by bc-1, bc-1 2 , bc-2 and bc-2 2 recessive alleles in common bean and assigned to PG VII. This isolate shared high (99 %) sequence identity with previously identified BCMV RU-1 and RU-1-related strains (RU1-OR-B and RU1-OR-C) according to a BLAST analysis of the nucleotide sequences of RT-PCR amplified products comprising the complete coat protein and 3′ partial NIb regions. The isolates TR-203 and TR-256 produced a distinctive reaction pattern in the dominant I gene-bearing bean cultivars Amanda and Isabella at lower (<30 °C) temperatures and were classified into PG IVb. These isolates were found to be 99 % identical to US-1 strain based on 3′ terminal nucleotide sequences of the BCMV genome. A fourth isolate, TR-243, involved mixed BCMV populations, as confirmed by partial nucleotide sequence analysis; one was classified as belonging to PG VII being similar to TR-180, and another was assigned to PG IVb. In conclusion, on the basis of both the reactions of differential bean cultivars and ELISA results, most of BCMV isolates were assigned to pathogroup PG VII and BCMNV isolates to PG VIb. This study is the first to show that four recessive resistance alleles of common bean can be overcome by a single field isolate of BCMV, and that a wide range of BCMV pathogroups are present in Turkey. 相似文献
4.
基于WorldView-2影像的土壤含盐量反演模型 总被引：1，自引：0，他引：1
针对WorldView-2影像高空间分辨率评价其定量反演土壤含盐量的能力,以盐渍化现象较为明显的新疆克里雅河流域为研究对象,基于WorldView-2影像和实测高光谱数据,利用偏最小二乘回归(partial least squares regression,PLSR)和BP人工神经网络(back propagation artificial neural networks,BP ANN)方法建立定量反演该流域土壤含盐量模型并做出研究区高空间分辨率土壤含盐量分布图。结果表明:1)利用实测高光谱数据和影像数据分别建立的2种模型中BP神经网络模型预测精度都高于PLSR模型,其中基于影像数据建立的6:8:1结构的3层BP神经网络模型决定系数R2、均方根误差RMSE、相对分析误差RPD分别为0.851、0.979、2.337,模型的稳定性和预测能力都优于PLSR模型(R2、RMSE、RPD分别为0.814、1.139、2.007)。2)利用WorldView-2影像提高了土壤含盐量制图的空间分辨率,归一化植被指数NDVI和比例植被指数RVI较有效降低了植被覆盖与土壤水分对预测精度的影响。该文建立的考虑植被覆盖与土壤水分定量反演土壤含盐量的模型不需要复杂的参数,一定程度上满足了干旱、半干旱地区的盐渍化监测需求,可以促进WorldView-2等高空间分辨率卫星在盐渍化监测中的进一步应用。 相似文献
5.
基于高光谱特征和偏最小二乘法的春小麦叶绿素含量估算 总被引：4，自引：4，他引：4
叶绿素含量是影响作物生长及产量的主要因素。该研究以2017年6月小型试验田获取的抽穗期春小麦叶绿素含量及其对应的光谱反射率为数据源,对红边(627~780 nm)、黄边(566~589 nm)、蓝边(436~495 nm)、绿边(495~566 nm)、吸收谷和反射峰的最大反射率及反射率总和等16个高光谱特征参数与叶绿素含量之间的相关性进行了分析,并结合偏最小二乘回归法(partial least-squares regression,PLSR)对叶绿素含量进行高光谱建模及验证。结果表明:1)对特定的16个光谱特征参数而言,光谱特征参数绿边最大反射率与春小麦叶绿素质量分数之间的决定系数最低(R~20.5);决定系数较高(R~2≥0.5)的光谱特征参数包括蓝边最大反射率、蓝边反射率总和、黄边最大反射率、黄边反射率总和、红边最大反射率、红边反射率总和、绿边反射率总和、820~940 nm反射率总和及最大反射率、500~670 nm归一化吸收深度和560~760 nm归一化吸收深度,其中820~940 nm反射率总和决定系数达到最高(R~2为0.8);2)利用16个特征参量进行PLSR建模后,发现波段范围在820~940 nm的最大反射率及反射率总和所建立的PLSR估算模型为最优模型,其精度参数R~2p=0.8、RMSEp=2.0 mg/g、RPD=3.2。因此,该模型具有极好的预测能力。该研究为相关研究及当地精准农业提供科学支持和应用参考。 相似文献
6.
遥感技术在大尺度土壤盐渍化检测方面有着宏观性、实时性、动态性等优势和广阔的应用前景,但是传统的遥感图像分类方法精度不高、分类效率较低和不确定性.提出了基于支持向量机(SupportVectorMachine,SVM)的分类方法,介绍了SVM算法的基本原理,通过支持向量机分类法与传统分类方法(最大似然法和最小距离法)在盐渍化信息提取结果上进行对比,表明基于SVM的遥感图像分类方法能够较好的检测土壤的盐渍化信息,分类总精度达到95.66%,比最大似然法和最小距离法分类精度(分别为91.54%和85.42%)更高,因此更适合于遥感图像分类和盐渍化信息检测. 相似文献
7.
Ilyas Ahmad Malik Yousaf Ali Mohammad Saleem Ghulam Rasul Tahir 《Field Crops Research》1989,20(4):251-259
The performance of seven mutants of mungbean along with parental types was studied at 41 different sites in three summer crop seasons from 1980 to 1982. The performance of mutants was also studied in spring in the fallow period preceding cotton, and in early summer in the fallow period between wheat harvest and rice/maize planting, to assess their suitability of growing as a catch-crop in these fallows.
The mutants yielded significantly higher and matured 2–4 weeks earlier than parental types, leaving sufficient time to sow the succeeding crops. The mutants were characteristically short-statured, and superior to their parents with respect to number of pods per plant, seed weight, harvest index and productivity per day, but similar in numbers of seeds per pod and seed protein content.
The stability of yield was estimated through regression analysis. Significant genotypic differences were observed among mutants and varieties. Some mutants were widely adapted whereas others performed better in favourable environments. The parental types tended to respond well under poor environments.
Owing to their higher yield potential, early and uniform maturity, and wide adaptability, four mutants were approved as commercial varieties in 1986. These mutants yield 30–50% higher than the parents, mature in 55–70 days, and are suited to both summer and spring crop seasons. Of these four mutants, two can be grown in the fallow period between wheat harvest and rice/maize planting. Because of their determinate plant type, non-shattering pod and top fruit-bearing habit, these mutants are also amenable to intercropping practices and mechanised harvesting operations.
The role of induced mutations for the improvement of mungbean is discussed. 相似文献
8.
Zara Ahmed Lydia C. Powell Navid Matin Andrew Mearns-Spragg Catherine A. Thornton Ilyas M. Khan Lewis W. Francis 《Marine drugs》2021,19(8)
Osteoarthritis (OA) is a multifactorial disease leading to degeneration of articular cartilage, causing morbidity in approximately 8.5 million of the UK population. As the dense extracellular matrix of articular cartilage is primarily composed of collagen, cartilage repair strategies have exploited the biocompatibility and mechanical strength of bovine and porcine collagen to produce robust scaffolds for procedures such as matrix-induced chondrocyte implantation (MACI). However, mammalian sourced collagens pose safety risks such as bovine spongiform encephalopathy, transmissible spongiform encephalopathy and possible transmission of viral vectors. This study characterised a non-mammalian jellyfish (Rhizostoma pulmo) collagen as an alternative, safer source in scaffold production for clinical use. Jellyfish collagen demonstrated comparable scaffold structural properties and stability when compared to mammalian collagen. Jellyfish collagen also displayed comparable immunogenic responses (platelet and leukocyte activation/cell death) and cytokine release profile in comparison to mammalian collagen in vitro. Further histological analysis of jellyfish collagen revealed bovine chondroprogenitor cell invasion and proliferation in the scaffold structures, where the scaffold supported enhanced chondrogenesis in the presence of TGFβ1. This study highlights the potential of jellyfish collagen as a safe and biocompatible biomaterial for both OA repair and further regenerative medicine applications. 相似文献
9.
Noshin Ilyas Fakhra Ambreen Nazima Batool Muhammad Arshad Roomina Mazhar Fatima Bibi 《Communications in Soil Science and Plant Analysis》2018,49(2):148-158
Crop rotation is a supportive management practice in which legumes greatly improve the growth and yield of subsequent cereal crops, particularly wheat. In this study, effects of mung bean (Vigna radiata)?? on the yield and quality of grains of following wheat crop were determined. An experiment was carried out with two sets of wheat (Triticum aestivum) crops: one grown following mung bean (Vigna radiata) crop and the other grown after a fallow period. Concentrations of macronutrients, sugar, protein, amino acids, and phytohormones of wheat were determined. The grain protein concentration of wheat was improved if cultivated after mung bean, and nitrogen and other macronutrients of wheat were increased significantly. In case of phytohormone contents in the wheat crop, abscisic acid concentration showed no change, but the concentrations of gibberellin increased significantly by 41% and indole acetic acid by 30% as a result of crop rotation. Sugar content in wheat cultivated after mung bean BRM-318 showed 10% increase and wheat protein content increased by 17% and 20%, respectively. The present study demonstrated that crop rotation simulated yield and improved the nutritional value of wheat grain compared to wheat which followed the fallow period. 相似文献
10.
于田绿洲土壤含盐量的空间异质性研究 总被引：1，自引：0，他引：1
在GIS背景之下,利用地统计学,结合于田绿洲2014年5月的土壤含盐量采样数据,研究于田绿洲土壤含盐量的空间变异特征。分析结果显示:各深度土壤含盐量的空间分布是不均匀的,主要是以弧状、斑状以及条带状存在,从总的空间分布的格局上来看,有一定的聚集趋势;研究区土壤含盐量主要受到荒漠化程度、植被覆盖度的影响。通过分析于田绿洲土壤含盐量的空间变异性,有利于快速诊断土壤盐渍化,也能够为提升土地的利用效率、保障区域的农田可持续利用提出决策依据。 相似文献