Determination of dexamethasone in bovine liver by chemiluminescence high-performance liquid chromatography.

A new method for the determination of dexamethasone (9alpha-fluoro-11beta,17alpha,21-trihydroxy-16alpha -methylpregna-1, 4-diene-3,20-dione) in bovine liver was developed. This new liquid-liquid extraction method comprises the addition of sodium hydroxide to the tissue sample followed by extraction with ethyl acetate. After centrifugation, the extract is evaporated to dryness and the residue dissolved in acetonitrile. The cleaning of the fat is performed with n-hexane, and the acetonitrile layer is evaporated. Analysis of the extracts is performed using high-performance liquid chromatography with chemiluminescence detection employing luminol as CL reagent. A series of recovery curves performed at spiking levels of 50, 30, 10, 5, and 2.5 ppb show that at least 80% of DEX can be recovered from liver and that the chemiluminescence detection yields satisfactory results with respect to sensitivity (LOD 0.2 ppb), reproducibility (CV% 10.7) and repeatability (CV% 6.2-8.9).     

Response of Tribolium castaneum (Coleoptera, Tenebrionidae) to Salpichroa origanifolia Withanolides.

Biological effects on Tribolium castaneum larvae were evaluated for three withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and for several chemically modified analogues. The compounds were incorporated into the larval diet at concentrations of 500 and 2000 ppm. Salpichrolide C (2) produced a significant delay in the development of neonate larvae to adults at the highest concentration (2000 ppm); development delays and lethal effects were produced by salpichrolides A (1) and G (3) at both concentrations assayed. The size of surviving adults was used as a criterion for assessing feedant deterrent effects; the results suggest that these compounds act as feeding inhibitors. Influence of chemical modifications in development delay was analyzed.     

A quantitative evaluation and phylogenetic characterization of oligotrophic denitrifying bacteria harbored in subsurface upland soil using improved culturability

This is the first investigation to show that oligotrophic denitrifying bacteria are dominant denitrifiers in subsurface upland soil. We examined the vertical distribution of denitrifying bacterial populations in upland soil using two kinds of enumeration media. The number of denitrifying bacteria, enumerated in subsurface soil layers by a 100-fold diluted nutrient broth (DNB) medium with NO₃ ⁻, was two to three orders of magnitude greater than those enumerated by a conventional nutrient broth medium with NO₃ ⁻, suggesting the dominance of oligotrophic denitrifying bacteria. Seventy-four percent of the total denitrifying bacterial isolates were DNB organisms of the oligotrophic type, which did not show appreciable growth on a conventional nutrient broth medium. The isolates were heterogeneous and were categorized as alpha (35 strains) and beta (19 strains) subdivisions of proteobacteria and high G+C gram-positive bacteria (7 strains) by 16S rRNA gene sequence analysis. The 35-alpha subdivision of proteobacterial isolates was of oligotrophic type and widely distributed from the surface to subsurface soil layers. Phylogenetic analysis indicated that some isolates belonged to groups with few or no cultivated representatives, and that one isolate may be a member of a new genus. This isolation procedure, using diluted media, is valuable in detecting diverse and novel denitrifying bacteria in the subsurface soil.     

Lethal and sublethal effects of withanolides from Salpichroa origanifolia and analogues on Ceratitis capitata

Biological effects on Ceratitis capitata were evaluated for several withanolides isolated from Salpichroa origanifolia (Solanaceae), (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-26-hydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide A, 1), (20S,22R,24S,25S,26R)-22,26:24,25-diepoxy-5alpha,6beta,26-trihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide C, 2), (20S,22R,24S,25S,26R)-5alpha,6alpha;22,26:24,25-triepoxy-15,26-dihydroxy-17(13-->18)abeo-ergosta-2,13,15,17-tetraen-1-one (salpichrolide G, 3), and (20S,22R,24S,25S,26R)-5alpha,6alpha:22,26:24,25-triepoxy-1,26-dihydroxy-17(13-->18)-abeo-ergosta-2,13,15,17-tetraene (salpichrolide B, 5), and for chemically modified analogues. Influence of chemical modifications on development delay was analyzed. The compounds were incorporated into the larval diet and the adults' drinking water. Significant development delays from larvae to puparia were observed in treatments with the natural withanolides salpichrolides A, C, and G (1-3) at a concentration of 500 ppm. Salpichrolide B (5) was the most toxic compound, the highest mortality (95%) being observed at the larval stage. Exposure of adults to drinking water containing natural withanolides 1-3 and 5 produced mortality in all cases.     

Reactivity of lysine moieties toward an epoxyhydroxylinoleic acid derivative: aminolysis versus hydrolysis.

Epoxyols are generally accepted as crucial intermediates in lipid oxidation. The reactivity of tert-butyl (9R,10S,11E,13S)-9, 10-epoxy-13-hydroxy-11-octadecenoate (11a,b) toward lysine moieties is investigated, employing N(2)-acetyllysine 4-methylcoumar-7-ylamide (12) as a model for protein-bound lysine. The prefixes R and S denote the relative configuration at the respective stereogenic centers. Independent synthesis and unequivocal structural characterization are reported for 11a,b, its precursors, and tert-butyl (9R,10R,11E, 13S)-10-(?5-(acetylamino)-6-[(4-methyl-2-oxo-2H-chromen-7-yl)amino ]-6 -oxohexyl?amino)-9,13-dihydroxy-11-octadecenoate (13a-d). Reactions of 11a,b and 12 in 1-methyl-2-pyrrolidone (MP) and MP/water mixtures at pH 7.4 and 37 degrees C for 56 days show formation of the aminols 13a-d to be favored by an increased water content. The same trend is observed for hydrolytic cleavage of 11a,b to tert-butyl (E)-9,10, 13-trihydroxy-11-octadecenoate (14) and tert-butyl (E)-9,12, 13-trihydroxy-10-octadecenoate (15). Under the given conditions, aminolysis proceeds via an S(N)2 substitution, in contrast with the S(N)1 process for hydrolysis. In the MP/water (8:2) incubation, 15. 8% of 12 has been transformed to 13a-d and 10.5% of 11a,b hydrolyzed to the regioisomers 14 and 15 after 8 weeks, respectively. Aminolysis of alpha,beta-unsaturated epoxides by lysine moieties therefore is expected to be an important mode of interaction between proteins and lipid oxidation products.     

Inhibition of extrahepatic human cytochromes P450 1A1 and 1B1 by metabolism of isoflavones found in Trifolium pratense (red clover)

Biochanin A and formononetin are the predominant isoflavones in red clover. In a previous study (J. Agric. Food Chem. 2002, 50, 4783-4790), it was demonstrated that human liver microsomes converted biochanin A and formononetin to genistein and daidzein. This paper now shows CYP1B1-catalyzed O-demethylation of biochanin A and formononetin to produce genistein and daidzein, respectively, which inhibit CYP1B1. Recombinant human CYP1A1 or CYP1B1 was incubated with biochanin A or formononetin. CYP1A1 catalyzed isoflavone 4'-O-demethylation and hydroxylations with similar efficiency, whereas CYP1B1 favored 4'-O-demethylation over hydroxylations. Three of the biochanin A metabolites (5,7,3'-trihydroxy-4'-methoxyisoflavone, 5,7,8-trihydroxy-4'-methoxyisoflavone, and 5,6,7-trihydroxy-4'-methoxyisoflavone) were characterized by 1H NMR spectroscopy and mass spectrometry. Daidzein (Ki = 3.7 microM) exhibited competitive inhibition of CYP1B1 7-ethoxyresorufin O-deethylase activity, and genistein (Ki = 1.9 microM) exhibited mixed inhibition. Biochanin A and/or formononetin may exert anticarcinogenic effects directly by acting as competitive substrates for CYP1B1 or indirectly through their metabolites daidzein and genistein, which inhibit CYP1B1.     

A resuscitation/selection system for rapid determination of Salmonella in foods

A resuscitation medium was developed consisting of a trypticase soy broth base supplemented with 0.5% yeast extract, 0.25% sodium pyruvate, 0.01% sodium thioglycollate, and 0.1% chicken fat. After a resuscitation period of 4 h, the medium was made selective by addition of either sodium thiosulfate, bile salts and iodine, or sodium selenite and L-cystine. The now selective medium was incubated for 16 h. The presence or absence of Salmonella was determined by the Salmonella-Tek antibody-based detection kit. The present system was compared with a method of the Bacteriological Analytical Manual (BAM) for naturally contaminated foods. Nineteen egg products were screened; 3/19 were positive using the BAM method, 9/19 were positive using the present system. Seventeen chicken samples were assayed; 10/17 were positive using the BAM method; 13/17 were positive using the present system. Of 8 pepper samples, 4/8 were positive using the BAM method; 6/8 were positive using the present system. Of 8 spice samples, 6/8 were positive using the BAM method, 7/8 were positive using the present system. Of 6 onion products sampled, 5/6 were positive using the BAM method; 6/6 were positive using the present system.     

Glycosylation of genistin into soluble inclusion complex form of cyclic glucans by enzymatic modification

The enzymatic modification of genistin to enhance its water solubility was studied using two glycosyltransferases, cyclodextrin glucanotransferase from alkalophilic Bacillus sp. I-5 and 4-alpha-glucanotransferase from Thermus scotoductus. Two different catalytic reactions, the transglycosylation and cyclization activities, were observed when the reaction was performed with soluble starch as a donor and genistin as an acceptor. The reaction products were isolated and identified as [Glc(alpha1-4)](1-22)-Glc(beta1-7)-genisteins and cycloamylose with DP 8-12 by HPLC and MALDI-TOF MS. A beta-amylase treatment revealed inclusion complexes composed of Glc(alpha1-4)-Glc(beta1-7)-genistein/Glc(alpha1-4)-Glc(alpha1-4)-Glc(beta1-7)-genistein and cycloamylose with DP 8-12. The results indicated that the cycloamylose formed by the cyclization reaction of the enzyme included Glc(alpha1-4)-Glc(beta1-7)-genistein/Glc(alpha1-4)-Glc(alpha1-4)-Glc(beta1-7)-genistein. The presence of cycloamylopectin, in which the Glc(alpha1-4)-Glc(beta1-7)-genistein/Glc(alpha1-4)-Glc(alpha1-4)-Glc(beta1-7)-genistein was enclosed, was also observed with HPLC, HPSEC-MALLS, and MALDI-TOF MS analyses. The solubility of genistin was highly improved, and the solution containing glycosylated genistin and the inclusion complex demonstrated excellent properties of transparency and stability during storage at 4 degrees C.     

马来甜龙竹种胚培养增殖芽芽尖再生体系建立

为建立马来甜龙竹高效稳定的再生体系,本研究以马来甜龙竹种胚培养增殖芽的芽尖为试验材料,研究不同植物激素、有机添加物以及弱光处理对其再生体系建立的影响。结果表明,马来甜龙竹芽尖愈伤组织诱导较适宜培养基为添加0.5~1.0 mg·L^-1 NAA和3 mg·L^-1 2,4-D的MS培养基,致密颗粒状愈伤组织诱导率达61.7%;较适宜的分化培养基为添加1 mg·L^-1 6-BA、1 mg·L^-1 KT和0.25 mg·L^-1 NAA的MS培养基,10 μmol·m^-2·s^-1弱光处理6 d,分化率达46.67%,再生苗伸长生长良好;较适宜的生根培养基为添加3 mg·L^-1 IBA的1/2 MS培养基,生根率为55%,根较粗,其中部分根长有侧根。试管苗移植到混合基质中,成活率为83.33%。本研究初步建立了马来甜龙竹种胚培养增殖芽芽尖再生体系,为马来甜龙竹遗传转化体系的研究和应用奠定了基础。     

Selectivity of celite-immobilized patatin (lipid acyl hydrolase) from potato (Solanum tuberosum L.) tubers in esterification reactions As influenced by water activity and glycerol analogues as alcohol acceptors

Lipid acyl hydrolase (LAH; patatin) was purified from potato tubers by ammonium sulfate fractionation followed by anion-exchange and affinity chromatography. The major protein band of 40-43 kDa on SDS-PAGE appeared to be patatin, and it stained positive for lipase activity on native PAGE. Selectivity of a Celite-immobilized potato LAH in esterification reactions with n-acyl fatty acids (FA; C4, C6, C8, C10, C12, C14, C16, and C18) and alcohol acceptors (n-propanol, 2-propanol, 1,3-propanediol, and glycerol; 1,2-propanediol was not sufficiently reactive) was studied in isooctane. Immobilized LAH was highly selective for medium chain FAs (C8/C10) with a secondary optimum for chain lengths of C14/16. Water activity (a(w)) influenced activity and FA selectivity of the enzyme. Initial rates of ester synthesis were greatest at a(w) of 0.90 for all alcohol acceptors except for glycerol, where greatest initial rates were observed at a(w) of 0.19. Immobilized LAH preparations exhibited a bell-shape pH profile with optimum activity at pH 6-7 for ester synthesis, and no effect of pH on FA selectivity was observed.     

Pinolide, a new nonenolide produced by Didymella pinodes , the causal agent of ascochyta blight on Pisum sativum

An aggressive isolate of Didymella pinodes isolated from pea ( Pisum sativum ) produced four different metabolites in vitro. The metabolites isolated from the culture filtrates were characterized by spectroscopic and optical methods. A new nonenolide, named pinolide, was isolated and characterized as (2S*,7R*,8S*,5E,9R*)-2,7,8-trihydroxy-9-propyl-5-nonen-9-olide. Pinolidoxin, the main toxin produced by D. pinodes, was also isolated together with two other closely related nonenolides, identified as herbarumin II and 2-epi-herbarumin II. Herbarumin II and 2-epi-herbarumin II have been previously isolated from the fungi Phoma herbarum and Paraphaeosphaeria recurvifoliae , respectively, but described here to be isolated for the first time from D. pinodes. When tested on leaves of the host plant and other legumes and weeds, pinolidoxin was phytotoxic in all of the plant species, whereas the other three nonenolides did not produce any symptoms. The importance of the stereochemistry of the hydroxy group at C-7 on phytotoxicity also is discussed.     

Maple syrup phytochemicals include lignans, coumarins, a stilbene, and other previously unreported antioxidant phenolic compounds

Twenty-three phenolic compounds were isolated from a butanol extract of Canadian maple syrup (MS-BuOH) using chromatographic methods. The compounds were identified from their nuclear magnetic resonance and mass spectral data as 7 lignans [lyoniresinol (1), secoisolariciresinol (2), dehydroconiferyl alcohol (3), 5'-methoxy-dehydroconiferyl alcohol (4), erythro-guaiacylglycerol-β-O-4'-coniferyl alcohol (5), erythro-guaiacylglycerol-β-O-4'-dihydroconiferyl alcohol (6), and [3-[4-[(6-deoxy-α-l-mannopyranosyl)oxy]-3-methoxyphenyl]methyl]-5-(3,4-dimethoxyphenyl)dihydro-3-hydroxy-4-(hydroxymethyl)-2(3H)-furanone (7)], 2 coumarins [scopoletin (8) and fraxetin (9)], a stilbene [(E)-3,3'-dimethoxy-4,4'-dihydroxystilbene (10)], and 13 phenolic derivatives [2-hydroxy-3',4'-dihydroxyacetophenone (11), 1-(2,3,4-trihydroxy-5-methylphenyl)ethanone (12), 2,4,5-trihydroxyacetophenone (13), catechaldehyde (14), vanillin (15), syringaldehyde (16), gallic acid (17), trimethyl gallic acid methyl ester (18), syringic acid (19), syringenin (20), (E)-coniferol (21), C-veratroylglycol (22), and catechol (23)]. The antioxidant activities of MS-BuOH (IC50>1000 μg/mL), pure compounds, vitamin C (IC50=58 μM), and a synthetic commercial antioxidant, butylated hydroxytoluene (IC50=2651 μM), were evaluated in the diphenylpicrylhydrazyl (DPPH) radical scavenging assay. Among the isolates, the phenolic derivatives and coumarins showed superior antioxidant activity (IC50<100 μM) compared to the lignans and stilbene (IC50>100 μM). Also, this is the first report of 16 of these 23 phenolics, that is, compounds 1, 2, 4-14, 18, 20, and 22, in maple syrup.     

Chemometrical analysis of capillary electrophoresis casein fractions for predicting ripening times of milk mixture cheese

The effect of the ripening time on the proteolytic process in cheeses manufactured from mixtures of cow's and ewe's milk during a 167-day ripening period was monitored by capillary electrophoresis of the pH 4.6-insoluble fraction. Totals of 21 and 16 peaks were recognized and matched in the electropherograms obtained with a fused-silica capillary and a neutral capillary (hydrophilically coated), respectively. These peaks corresponded to intact bovine and ovine caseins and their hydrolysis products (e.g., alpha(s1)-casein, gamma-caseins). In 167-day-old cheeses, bovine alpha(s0)-casein (alpha(s1)-casein 9P) had been completely degraded and 6% of the residual bovine alpha(s1)-casein remained intact. Breakdown of the beta-casein fraction was lower than that of the alpha(s)-casein fraction. Finally, partial least-squares regression and principal component regression were used to predict the ripening time in cheeses. The root-mean-square errors in prediction by cross-validation were <7.8 days in all cases.     

几株固氮芽孢杆菌的分离与鉴定

摘要： 从小麦（Triticum aestivum）、玉米（Zea mays）、黑麦草（Lolium sp.）和柳树（Salix sp.）的根际土壤中分离得到能在无氮培养基上生长的29株芽孢杆菌（Bacilli），通过固氮酶活的测定以及固氮酶结构基因 nifH 的PCR扩增得到7株固氮芽孢杆菌。对这7株固氮菌株进行了生理生化性状测定、16S rDNA序列分析(GenBank accession No. AY373358, AY373360,~AY373364和AY376876)、G+C mol%含量的测定及DNA-DNA杂交实验，结果表明，其中5株菌属于芽孢杆菌，另外2株菌属于类芽孢杆菌。在这7株被鉴定的菌株中，菌株T1被鉴定为Bacillus cereus；菌株G1、C4和C5被鉴定为B. megaterium；菌株W5的生理生化性状、16S rDNA和G+C mol%与Bacillus marisflavi 相近；G2的生理生化性状和16S rDNA 与Paenibacillus polymyxa 接近，但在基于16S rDNA的系统发育树中却与P. durus 聚在最小的分支内；T7可能是Paenibacillus属中的一个新种。     

鸡胚精原干细胞定向诱导分化为脂肪细胞的研究

为研究体外定向诱导鸡胚精原干细胞（Spermatogonial stem cells, SSCs）向脂肪细胞分化的能力，取孵化16d的鸡胚睾丸，无菌获取SSCs，体外培养传代。采用不同诱导程序、不同组合的诱导剂（地塞米松、胰岛素、3-异丁基-1-甲基黄嘌呤（IBMX））诱导SSCs向脂肪细胞分化。结果显示SSCs被诱导7～21d后，分化成脂肪细胞，其中诱导程序⑥的诱导分化效果较好，分化率为85%。诱导剂联合协同作用的诱导效果极显著地(P<0.01)高于单独作用的诱导效果。诱导的脂肪细胞经特异性的油红O染色为阳性，并高表达脂肪细胞标志基因PPARγ。表明鸡胚胎精原干细胞（SSCs）体外培养传代后仍具有多向分化潜能，在特异性化学物质的诱导下，可被定向诱导分化为脂肪细胞。     

Antioxidative compounds from the outer scales of onion

Antioxidative compounds were isolated from the methanol extract of dry outer scales of onion (Allium cepa L.). Nine phenolic compounds (1-9) were finally obtained by reversed-phase high-performance liquid chromatography, and their structures were elucidated by NMR and mass spectrometry analyses. They were the six known compounds, protocatechuic acid (1), 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (2), quercetin 4'-O-beta-D-glucopyranoside (3), quercetin (5), 4'-O-beta-d-glucopyranoside of quercetin dimer (7), and quercetin dimer (8), and three novel compounds, condensation products of quercetin with protocatechuic acid (4), adduct of quercetin with quercetin 4'-O-beta-D-glucopyranoside (6), and quercetin trimer (9). These phenolic compounds were tested for their antioxidant properties using autoxidation of methyl linoleate in bulk phase or free radical initiated peroxidation of soybean phosphatidylcholine in liposomes. The flavonoid compounds having o-dihydroxy substituent in the B-ring were shown to be effective antioxidants against nonenzymic lipid peroxidation.     

Soybean Seed Aging and Environmental Factors on Seedling Growth

The effect of seed vigor on seed emergence depends on the type of environmental stress present at the time of seed germination and establishment. Therefore, the aim of this study was to assess the interaction of environmental stresses and aging on soybean (Glycine max L.) seed emergence. A factorial arrangement of treatments imposed on a randomized complete block design with four replications was conducted. Treatments of seed aging for 12, 24, 36, and 48 h at 41°C, salinity (6 and 12 ds/m²), water deficiency (–4 and–9 MPa), and sowing at depths of 3 and 7 cm were selected. Growth measurements were completed 21 and 55 days after planting. Analysis of variance was performed using the regression method for quantitative treatments such as seed aging, and if interactions were significant, interaction slicing was utilized and means compared with least significant difference tests (0.05). For quantitative treatments, regression analysis was conducted and path analysis was performed on growth traits. Results showed that aging had a significant effect on maximum emergence and rate of emergence. The ranking of the stress factors from most to least injurious for maximum emergence were severe salinity, severe drought, medium salinity, sowing depth of 7 cm, and medium drought. Harmful stress conditions on the plant leaf area and seedling dry weight were severe salinity, medium salinity, severe drought, medium drought, and sowing depth of 7 cm (only for seedling dry weight). Relative growth rate, net absorption rate, and leaf area ratio were not affected by aging but were affected by environmental conditions. These findings indicate that the impacts of environmental conditions are at least partially controlled by seed vigor.     

菲降解菌的分离鉴定及其在污染土壤生物修复中的应用

采用室内培养方法,从吴江市郊长期被多环芳烃污染的土壤中富集到以菲为唯一碳源和能源的菲降解复合微生物菌群,复合菌群在7d内对无机盐液体中菲（含量100mg·L^-1）的降解率达到99%。从复合菌群中分离纯化获得两株菲高效降解菌B1和L2,经过菌体形态特征、生理生化特征和16SrDNA序列分析,鉴定菌株B1为百日咳博行特氏菌（Bordetella petrii）,菌株L2为墨西哥假黄单胞菌（Pseudoxanthomonas mexicana）。这两株菌在菲含量为100mg·L^-1的无机盐培养液中,7d内对菲（含量100mg·L^-1）的降解率大约为80%,9d内的降解率可达到99%。将复合菌群和菲污染土壤混合,在光照培养箱中进行培养修复。结果表明,修复88d后,接种复合菌群的低污染浓度（8.22mg·kg^-1）处理和高污染浓度（39.65mg·kg^-1）处理的菲去除率分别达到95.74%和98.06%。     

连云港市云台山宜林荒山立地质量分类及评价

以江苏省连云港市云台山22个宜林荒山地段为研究对象,共选取了16个立地因子,将其分成宏观因子和微观因子分别进行立地质量分类及评价,最后再综合起来评价。评价结果表明,22个地段最终分成5类。第1类主要特征为土层中上偏厚,宏观立地质量相对较好,土壤质量中等,包括2个地段;第2类为土层中上偏厚,宏观立地质量相对较好,土壤质量差,包括4个地段;第3类为土层中下偏薄,宏观立地质量相对一般,土壤质量中等,包括7个地段;第4类为土层中下偏薄,宏观立地质量相对一般,土壤质量差,包括7个地段;第5类主为土层非常薄,宏观立地质量很差,土壤质量中等,包括2个地段。综合分析表明,研究区立地质量整体不高,今后绿化造林任务十分艰巨。     

川南杂交中稻-再生稻高产品种产量形成特点

为探索四川南部冬水田区杂交中稻-再生稻高产品种的产量穗粒构成,本试验以近年通过国家长江上游区试和四川省区试审定的36个杂交中稻新品种为材料,于2018—2020年在有代表性的江安、富顺、隆昌、泸县、南溪5个生态点,统一采用目前大面积生产应用的杂交中稻蓄留再生稻的高产栽培技术,研究了高产品种的产量形成特点。结果表明,两季产量11 000 kg·hm^-2以上品种有内5优907、内香优138、内香优103等16个品种。头季稻穗粒性状对其产量影响的多元回归分析F值达显著或极显著水平,对再生稻产量多元回归分析F值极显著(F值为22.18,n=180),且与两季总产量的关系极显著(F值为14.65,n=180)。选择头季稻、再生稻、两季总产分别高于10 000 kg·hm^-2、4 000 kg·hm^-2和13 500 kg·hm^-2的43组高产数据,分析发现再生稻产量与头季稻产量呈极显著负相关关系(y=12 161-0.867 6x,r=0.557 2)。由此可知,大穗型品种表现出头季稻高产、再生力相对较弱的特点,穗数型品种则具有再生力强和两季总产量较高的优势,两季总产量高的头季稻穗粒结构为有效穗数230.72~257.85万·hm^-2、穗粒数167.50~194.44粒、结实率78.80%~90.79%、千粒重22.60~29.33 g。本研究结果为川南杂交中稻蓄留再生稻大面积生产的高产品种选择和栽培技术的制定提供了新的科学依据。