播期和密度对棉花叶柄和根系硝态氮含量的影响

为探讨大田棉花氮代谢随播期和密度的变化规律,选用华棉3109(G.hirsutum L.)于2014年在华中农业大学试验农场,采用裂区设计:播期(月-日)(S1,05-30;S2,06-14)为主区,密度(株·m-2)(D1,7.5;D2,9.0;D3,10.5)为副区,研究了硝态氮含量在主茎叶柄和根系的分布特点。结果表明:1)随生育进程推进,叶柄和根系硝态氮含量先升高后降低,初花期最高。2)主茎叶柄硝态氮含量随叶位变化,蕾期、初花期由上而下逐渐降低,第1叶最高;盛花期逐渐增高,第1叶和第4叶最高;不同生育时期棉花叶柄硝态氮含量在叶位间的下降幅度随播期推迟而降低,随密度增加先升高后降低。3)播期和密度对不同生育时期棉花叶柄和根系硝态氮平均含量的交互作用均显著,但播期和密度主效应影响不同:见花施肥前,随推迟播期,棉花叶柄硝态氮平均含量显著降低了42.9%,根系硝态氮平均含量显著升高了12.1%,增加密度对叶柄和根系硝态氮平均含量无显著影响。见花施肥后,随播期的推迟,叶柄硝态氮平均含量无显著性变化,初花期平均为5.05 mg·g-1,盛花期平均为2.62 mg·g-1;而根系硝态氮平均含量,初花期S1S2,盛花期S1S2;随密度增加,D1,D2与D3初花期叶柄和根系硝态氮平均含量均显著降低;盛花期叶柄硝态氮平均含量呈先升高后降低趋势变化,而根系硝态氮平均含量则与初花期相反,呈显著递增趋势。综上所述,晚播高密条件下,见花一次施肥后,推迟播期不改变棉花地上部叶柄硝态氮平均含量水平,适度增加密度有利于棉花叶柄维持较高的硝态氮含量,有利于为叶片氮代谢提供充足的底物。     

The Determination of Nematode Tolerance and Seedling Performance of The Selected Almond (Prunus amygdalus L.) Genotypes in Isparta Province

In the present study, selected almond genotypes in Keciborlu/Isparta region by Y?ld?r?m (2007) based on late blooming and superior nut chacteristics were used to evaluate seedling growth performances and the reaction to root knot nematodes. Seeds were planted on perlite medium and stored 60 days at +4 ^°C in order to break seed dormancy. After germinating, seedlings were transferred to plastic pots to evaluate seedling growth characteristics and remaining seedlings were inoculated with Meloidogyne javanica and Meloidogyne incognita in order to asses resistance status of the selected seedlings. The highest germination percentage was obtained from Genotype 54 (96.1?%), the highest plant was observed from Genotype 9 (62.18 cm), the longest primary root was found from Genotype 54 (30.28 cm), the average secondary root lenght was highest in Genotype 9 (31.04 cm) and the widest root collar was observed in Genotype 33 (8.38 mm). Seedling stem diameter changed between 4.76 mm (Genoype 40) to 7.67 mm (Genotype 33). The lowest variation for stem widht was observed in Genotype 55 (0.58?%) while the lowest variation for seedling hight was found in Genotype 33 (0.50?%). Evaluated almond genotypes showed different reactions to studied nematode species, M. javanica and M. incognita. Resistant reactions of almond genotypes to nematode species were classified as susceptible, tolerant and resistant based on gal index values. Genotype 9 and 31 classified as tolerant to M. javanica while Genotype 54 classified as resistant to M. incognita.     

First detection and molecular characterization of avian polyomavirus in young parrots in Pakistan

Veterinary Research Communications - Avian polyomavirus (APV) infection, also called as budgerigar fledgling disease (BFD) causes various health problems in many psittacine species which may cause...     

Cryptocaryon irritans recombinant proteins as potential antigens for sero‐surveillance of cryptocaryonosis

Cryptocaryonosis is a major problem for mariculture, and the absence of suitable sero‐surveillance tools for the detection of cryptocaryonosis makes it difficult to screen Cryptocaryon irritans‐infected fish, particularly asymptomatic fish. In this study, we proposed a serum‐based assay using selected C. irritans proteins to screen infected and asymptomatic fish. Eight highly expressed genes were chosen from an earlier study on C. irritans expressed sequence tags and ciliate glutamine codons were converted to universal glutamine codons. The chemically synthesized C. irritans genes were then expressed in an Escherichia coli expression host under optimized conditions. Five C. irritans proteins were successfully expressed in E. coli and purified by affinity chromatography. These proteins were used as antigens in an enzyme‐linked immunosorbent assay (ELISA) to screen sera from experimentally immunized fish and naturally infected fish. Sera from both categories of fish reacted equally well with the expressed C. irritans recombinant proteins as well as with sonicated theronts. This study demonstrated the utility of producing ciliate recombinant proteins in a heterologous expression host. An ELISA was successfully developed to diagnose infected and asymptomatic fish using the recombinant proteins as antigens.     

Evaluation of Three Chitin Metal Silicate Co-Precipitates as a Potential Multifunctional Single Excipient in Tablet Formulations

The performance of the novel chitin metal silicate (CMS) co-precipitates as a single multifunctional excipient in tablet formulation using direct compression and wet granulation methods is evaluated. The neutral, acidic, and basic drugs Spironolactone (SPL), ibuprofen (IBU) and metronidazole (MET), respectively, were used as model drugs. Commercial Aldactone^®, Fleximex^® and Dumazole^® tablets containing SPL, IBU and MET, respectively, and tablets made using Avicel^® 200, were used in the study for comparison purposes. Tablets of acceptable crushing strength (>40 N) were obtained using CMS. The friability values for all tablets were well below the maximum 1% USP tolerance limit. CMS produced superdisintegrating tablets (disintegration time < 1 min) with the three model drugs. Regarding the dissolution rate, the sequence was as follow: CMS > Fleximex^® > Avicel^® 200, CMS > Avicel^® 200 > Dumazole^® and Aldactone^® > Avicel^® 200 > CMS for IBU, MET and SPL, respectively. Compressional properties of formulations were analyzed using density measurements and the compression Kawakita equation as assessment parameters. On the basis of DSC results, CMS co precipitates were found to be compatible with the tested drugs. Conclusively, the CMS co-precipitates have the potential to be used as filler, binder, and superdisintegrant, all-in-one, in the design of tablets by the direct compression as well as wet granulation methods.     

Thermal,swelling and stability kinetics of chitosan based semi-interpenetrating network hydrogels

The present study is focused on studying the swelling kinetics, thermal and aqueous stabilities, and determination of various forms of water in the chitosan (CS) and polyacrylonitrile (PAN) blend and semi-interpenetrating polymer network (sIPN). CS/PAN blend hydrogel films were prepared by solution casting technique. The blend film with optimum swelling properties was selected for the synthesis of sIPN. CS in the blend was crosslinked with the vapors of Glutaraldehyde (GTA) to prepare sIPN. The fabricated CS/PAN blend and sIPN hydrogels films were characterized with Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and field emission scanning electron microscope (FESEM). The kinetics of swelling, bound and unbound waters and aqueous stability were determined experimentally. FESEM showed good miscibility between CS and PAN, FTIR showed no chemical interaction between CS and PAN; however, it did show a doublet for the sIPN, TGA showed improved thermal stability and swelling kinetic followed second order kinetics. The degree of swelling of the sIPN hydrogels samples at room temperature varied from ~2200 % (with a fair degree of stability (~30 %)) to ~1000 % (with high degree of aqueous stability (43 %)) with increase in the crosslinking time. The calculated unbound water (W_UB) max., for the blend was 52.3 % whereas for the bound (W_B) the max., was 41.9 %. However, for sIPN hydrogel films, the W_UB water decreased (max. 21.0 %) where as the W_B increased (max. 52.0 %). The decrease in W_UB and increase in the W_B is attributed to the formation of a compact structure and increase in the contact area between the water and polymers in sIPN hydrogels due to the induction of new water contacting point in these hydrogel films, respectively.     

Field studies on the biological control of nematode parasites of sheep in the tropics, using the microfungus Duddingtonia flagrans

Long-term field studies were conducted on two government managed small ruminant research farms, located in different geo-climatic regions and approximately 300 km separate from each other, on Peninsula Malaysia. The Infoternak trial (48 weeks) and the Chalok trial (43 weeks) each compared nematode parasite control in separately managed groups of young sheep, either short-term rotationally grazed around a suite of 10 paddocks in addition to receiving a daily supplement of Duddingtonia flagrans spores (Fungus Group); or similar groups of sheep being rotationally grazed alone (Control Group). The prevailing weather conditions at Infoternak farm were of below average rainfall conditions for the most of the trial. As a consequence, only very low worm infections (almost exclusively Haemonchus contortus) were acquired by the 17 sets of tracer lambs that grazed sequentially with the experimental lambs. However on all except 2 occasions in the early part of the trial, the mean tracer worm burdens were significantly lower (P < 0.05) and the experimental lambs grew significantly better (P = 0.054) in the Fungus Group. Rainfall at Chalok farm during the course of the trial was also below average. As a consequence infectivity of pastures was assumed to be relatively low based on faecal egg counts (epg) of the experimental sheep, which following an anthelmintic treatment prior to allocation, remained very low in both treatment groups. Faecal egg counts of undosed replacement lambs in the latter half of the Chalok study, showed a progressive increase in the Control Group to levels exceeding 3000 epg, whereas the Fungus Group remained static at approximately 500 epg. These results show that the deployment of the nematophagous fungus, D. flagrans, can improve the level of parasite control of sheep in the tropics above that which can be achieved by the short-term rotational grazing strategy alone.     

Into the vault of the Vavilov wheats: old diversity for new alleles

Intensive selection in wheat (Triticum aestivum L.) breeding programs over the past 100 years has led to a genetic bottleneck in modern bread wheat. Novel allelic variation is needed to break the yield plateau, particularly in the face of climate change and rapidly evolving pests and pathogens. Landraces preserved in seed banks likely harbour valuable sources of untapped genetic diversity because they were cultivated for thousands of years under diverse eco-geographical conditions prior to modern breeding. We performed the first genetic characterisation of bread wheat accessions sourced from the N. I. Vavilov Institute of Plant Genetic Resources (VIR) in St Petersburg, Russia. A panel comprising 295 accessions, including landraces, breeding lines and cultivars was subject to single seed descent (SSD) and genotyped using the genotyping-by-sequencing Diversity Arrays Technology platform (DArT-seq); returning a total of 34,311 polymorphic markers (14,228 mapped and 20,083 unmapped). Cluster analysis identified two distinct groups; one comprising mostly breeding lines and cultivars, and the other comprising landraces. Diversity was benchmarked in comparison to a set of standards, which revealed a high degree of genetic similarity among breeding material from Australia and the International Maize and Wheat Improvement Center (CIMMYT). Further, 11,025 markers (1888 mapped and 9137 unmapped) were polymorphic in the diversity panel only, thus representing allelic diversity potentially not present in Australian or CIMMYT germplasm. Open-access to DArT-seq markers and seed for SSD lines will empower researchers, pre-breeders and breeders to rediscover genetic diversity in the VIR collection and accelerate utilisation of novel alleles to improve wheat.     

Lethal temperature for pinewood nematode, Bursaphelenchus xylophilus, in infested wood using radio frequency (RF) energy

We evaluated radio frequency (RF) dielectric heating for eradication of pinewood nematodes (PWN) in infested wood. Thirteen temperatures were tested (from ambient to 70 °C) on small wood samples (2.5 × 3.8 × 0.64 cm) to determine the minimum lethal temperature (100 % mortality), which was 56 °C [based on infra-red (IR) thermal images data 55.5–57.4 °C] with a 1 min hold time. We also used thermal probes inside the wood to confirm that temperatures were ≥56 °C. Thirty additional samples were tested bracketing the minimum lethal temperature using 54, 56 and 58 °C with additional replications to produce the minimum sample size equivalent of 100 % mortality of at least 93,616 nematodes to satisfy the Probit 9 efficacy requirement. This minimum lethal temperature was further verified by treating infested large wood blocks (10.2 × 10.2 × 25.4 cm). All samples that met or exceeded the 56 °C lethal temperature for the required 1 min hold time (as measured by probes inserted in the wood and on the wood surface by IR) produced 100 % mortality. The sample size required to show Probit 9 efficacy was also satisfied. This study supports the consideration of RF in addition to microwave (MW) dielectric heating as alternative treatments of wood packaging material for inclusion in ISPM No. 15, provided the treatment delivers the target lethal temperature throughout the profile of the material in industrial scale operations.