Applicability of the modified mooney-rivlin equation on rheological analysis of fish-meat gel

Rheological properties of fish-meat gels were investigated according to the modified Mooney-Rivlin equation and the three-element model representing large and small deformation theories, respectively. The Mooney-Rivlin equation was developed considering directly the volume change with the strain for characterizing rheological property of fish-meat gel. The results led to the conclusion that using the modified large-deformation equation considering volume, changes of samples were more useful to investigate effectively the mechanical behavior of fish-meat gels. The volume changes of fish-meat gel with the, strain resulted that fish-meat gel kept the linearity under about 0.2–0.3 compression strain in stress-strain relation. The stress-relaxation test of fish-meat gel was performed under the strain of 0.25 in the compression process. The elastic moduli and viscosity were decreased with the moisture contents of the gels. These results indicated the same trend as the results according to the modified Mooney-Rivlin equation. Comparing the results according to the large and small deformation theories led to the proportional relationships between the elastic modulus values and the Mooney-Rivlin constants, C ₁ and C ₂.     

Response of upland cotton (<Emphasis Type="Italic">G.hirsutum</Emphasis> L.) genotypes to drought stress using drought tolerance indices

Drought tolerance as such is often not considered to be an independent trait by plant breeders. The objective of this study was to evaluate eight drought tolerance indices, namely stress susceptibility index (SSI), yield stability index (YSI), yield reduction ratio (Yr), yield index (YI), tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI) in upland cotton (G. hirsutum L.) genotypes. For this purpose, 16 genotypes were sampled during the 2013-2014 growing seasons under both normal and drought-stress field conditions at the Main Cotton Research Station of Navsari Agricultural University, Surat, India. The drought tolerance indices were calculated based on seed cotton yield under drought stress and non-stress conditions. Mean comparison of drought tolerance indices and seed cotton yield validated the significant influences of drought stress on yield as well as significant differences among genotypes. Results of calculated correlation coefficients and multivariate analyses showed that GMP, MP and STI indices were able to discriminate drought-sensitive and tolerant genotypes. Cluster analysis using the drought-tolerance indices divided the 16 genotypes into tolerant and susceptible groups. Two genotypes, G.Cot.16 × H-1353/10 and H-1353/10 × G.Cot.16 gave good yield response under drought conditions leading to their stability during water stress conditions. Based on multivariate analyses using the indices individually or in combinations, it was possible to identify the most yield-stable genotypes across the environments. Overall, we concluded that GMP, MP and STI indices can be efficiently exploited not only for screening drought tolerance but also to identify superior genotypessuitable for both stress and non-stress field conditions.     

草甘膦生物抗性和生物降解及其转基因研究

草甘膦(N—phosphonomethyl—glycine，glyphosate)毒性作用机理是竞争性抑制莽草酸途径中的5-烯醇丙酮莽草酸-3-磷酸合成酶(5-enolpyruvyl—shikimate—3—phosphate synthase，简称EPSP合成酶)的活性。EPSP合成酶是植物和微生物体内芳香族氨基酸(包括色氨酸、酪氨酸、苯丙氨酸等)生物合成过程中的一个关键酶。该酶由aroA基因编码。抗草甘膦微生物或植物中EPSP合成酶基因的核苷酸序列在相同或相近位点发生了突变。将编码EPSP合成酶的突变基因导入大豆和烟草等作物中，均能获得转基因的抗草甘膦作物。草甘膦的生物降解途径主要有两条，C-N断裂生成氨甲基磷酸(AMPA)或C-P键断裂生成肌氨酸(sarcosine)，然后两种中间代谢物进一步代谢为磷酸、甘氨酸和二氧化碳等。     

Inheritance of time to flowering in cowpea (<Emphasis Type="Italic">Vigna unguiculata</Emphasis> (L.) Walp.)

Time to flowering and maturity is an important adaptive feature in annual crops, including cowpeas (Vigna unguiculata (L.) Walp.). In West and Central Africa, photoperiod is the most important environmental variable affecting time to flowering in cowpea. The inheritance of time from sowing to flowering (f) in cowpeas was studied by crossing a photoperiod-sensitive genotype Kanannnado to a photoperiod-insensitive variety IT97D-941-1. Sufficient seed of F₁, F₂, F₃ and backcross populations were generated. The parental, F₁, F₂, F₃ and the backcross populations were screened for f under long natural days (mean daylength 13.4 h per day) in the field and the parents, F₁, F₂ and backcross populations under short day (10 h per day) conditions. The result of the screening showed that photoperiod in the field was long enough to delay flowering of photoperiod-sensitive genotypes. Photoperiod-sensitivity was found to be partially dominant to insensitivity. Frequency distribution of the trait in the various populations indicated quantitative inheritance. Additive (d) and additive × dominance (j) interactions were the most important gene actions conditioning time to flowering. A narrow sense heritability of 86% was estimated for this trait. This will result in 26 days gain in time to flowering with 5% selection intensity from the F₂ to F₃ generation. At least seven major gene pairs, with an average delay of 6 days each, were estimated to control time to flowering in this cross.     

Quantitative trait loci for temperature-sensitive resistance to <Emphasis Type="Italic">Puccinia striiformis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis> in wheat cultivar Flinor

Stripe (yellow) rust, caused by Puccinia striiformis Westend. f. sp. tritici Eriks. (Pst), is an important disease of wheat (Triticum aestivum L.) globally. Use of host resistance is an important strategy to manage the disease. The cultivar Flinor has temperature-sensitive resistance to stripe rust. To map quantitative trait loci (QTLs) for these temperature-sensitive resistances, Flinor was crossed with susceptible cultivar Ming Xian 169. The seedlings of the parents, and F₁, F₃ progeny were screened against Chinese yellow rust race CYR32 in controlled-temperature growth chambers under different temperature regimes. Genetic analysis confirmed two genes for temperature-sensitive stripe rust resistance. A linkage map of SSR markers was constructed using 130 F₃ families derived from the cross. Two temperature-sensitive resistance QTLs were detected on chromosome 5B, designated QYr-tem-5B.1 and QYr-tem-5B.2, respectively, and are separated by a genetic distance of over 50 cM. The loci contributed 33.12 and 37.33% of the total phenotypic variation for infection type, respectively, and up to 70.45% collectively. Favorable alleles of these two QTLs came from Flinor. These two QTLs are temperature-sensitive resistance loci and different from previously reported QTLs for resistance to stripe rust.     

区域稻田土壤碳储量的空间分布特征

基于土壤类型法估算重庆市巴南区稻田土壤有机碳储量及其空间分布特征,结果表明：研究区稻田土壤有机碳总储量约为6.48×106 t,平均土壤有机碳密度为8.31 kg m-2,略高于全国平均水平。重庆市巴南区稻田0-20 cm土壤有机碳密度介于1.73~3.70 kg m-2 之间,剖面土壤有机碳密度介于5.13~14.07 kg m-2之间。0-20 cm和100 cm土壤有机碳储量分别为1.18×106 t和4.39×106 t,0-20 cm土壤有机碳储量为0-100 cm碳储量的27.50%,说明碳储量主要富集在表层土壤。土壤有机碳密度呈带状分布,且具有高度的不均匀性,同类土壤具有相似的有机碳蓄积量。     

Genetic Characterization of Brazilian Annual <Emphasis Type="Italic">Arachis</Emphasis> Species from Sections <Emphasis Type="Italic">Arachis</Emphasis> and <Emphasis Type="Italic">Heteranthae</Emphasis> using RAPD Markers

The genus Arachis is divided into nine taxonomic sections. Section Arachis is composed of annual and perennial species, while section Heteranthae has only annual species. The objective of this study was to investigate the genetic relationships among 15 Brazilian annual accessions from Arachis and Heteranthae using RAPD markers. Twenty-seven primers were tested, of which nine produced unique fingerprintings for all the accessions studied. A total of 88 polymorphic fragments were scored and the number of fragments per primer varied from 6 to 17 with a mean of 9.8. Two specific markers were identified for species with 2n = 18 chromosomes. The phenogram derived from the RAPD data corroborated the morphological classification. The bootstrap analysis divided the genotypes into two significant clusters. The first cluster contained all the section Arachis species, and the accessions within it were grouped based upon the presence or absence of the ‘A’ pair and the number of chromosomes. The second cluster grouped all accessions belonging to section Heteranthae.     

Biopore history determines the microbial community composition in subsoil hotspots

Biopores are hotspots of nutrient mobilisation and shortcuts for carbon (C) into subsoils. C processing relies on microbial community composition, which remains unexplored in subsoil biopores. Phospholipid fatty acids (PLFAs; markers for living microbial groups) and amino sugars (microbial necromass markers) were extracted from two subsoil depths (45–75 cm ; 75–105 cm) and three biopore types: (I) drilosphere of Lumbricus terrestris L., (II) 2-year-old root biopores and (III) 1.5-year-old root biopores plus six 6 months of L. terrestris activities. Biopore C contents were at least 2.5 times higher than in bulk soil, causing 26–35 times higher Σ PLFAs g^-1 soil. The highest Σ PLFAs were found in both earthworm biopore types; thus, the highest soil organic matter and nutrient turnover were assumed. Σ PLFAs was 33% lower in root pores than in earthworm pores. The treatment affected the microbial community composition more strongly than soil depth, hinting to similar C quality in biopores: Gram-positives including actinobacteria were more abundant in root pores than in earthworm pores, probably due to lower C bioavailability in the former. Both earthworm pore types featured fresh litter input, promoting growth of Gram-negatives and fungi. Earthworms in root pores shifted the composition of the microbial community heavily and turned root pores into earthworm pores within 6 months. Only recent communities were affected and they reflect a strong heterogeneity of microbial activity and functions in subsoil hotspots, whereas biopore-specific necromass accumulation from different microbial groups was absent.     

Genetic Diversity in Tef [<Emphasis Type="Italic">Eragrostis tef</Emphasis> (Zucc.) Trotter] Germplasm

One hundred and forty-four heterogeneous tef germplasm accessions collected from 10 major tef growing areas in Ethiopia were evaluated for 18 quantitative traits in a simple lattice design, at Holetta and Ginchi, in 2001 main growing season to study the genetic diversity in tef. The combined analysis of variance revealed the presence of significant variation among germplasm accessions for all traits studied. Cluster analysis revealed the overlapping of the germplasm accessions from different origin and the accessions were grouped into eight distinct clusters of 1–78. Generalized distance square confirmed the presence of significant genetic distance between clusters. In principal component (Prin) analysis, the first four principal components with latent root values above one accounted for about 80.6% of the variability existing among the germplasm accessions. Prin1 constituted about 55% of the variability mainly from almost equal contribution of 10 quantitative traits, indicating that most of the traits are equally important in tef diversity. In this study, the regions and altitudes of origin were not found to have a substantial effect on the genetic diversity in tef germplasm. Diversity within the regions was found to be significant and, hence, an opportunity for exploitation in tef improvement.