Application of Micronutrients in Rice-Wheat Cropping System of South Asia

Rice-wheat cropping system(RWCS) is one of the most important cropping systems in South Asia. However, sustainability of this system is under threat owing to several factors, of which deficiency of micronutrients particularly zinc(Zn), boron(B) and manganese(Mn) is one of the major problems. Continuous rotation of rice and wheat, imbalanced fertilizer use and little/no use of micronutrient-enriched fertilizers induce deficiencies of Zn, B and Mn in the RWCS of South Asia. Here we review that(i) imbalanced fertilizer use and organic matter depletion deteriorate soil structure resulting in low efficiency of applied macro-and micro-nutrients in RWCS.(ii) The micronutrients(Zn, B and Mn) are essentially involved in metabolism of rice and wheat plants, including chlorophyll synthesis, photosynthesis, enzyme activation and membrane integrity.(iii) Availability and uptake of Zn, B and Mn from rhizosphere depend on the physico-chemical soil properties(which differ under aerobic and anaerobic conditions) including soil p H, soil organic matter, soil moisture and interaction of these micronutrients with other nutrients.(iv) Plant ability to uptake and utilize the nutrients is affected by several plant factors such as root architecture, root hairs, transport kinetics parameter and root exudates.(v) Crop management and application of these microelements can help correct the micronutrients deficiency and enhance their grain concentration.     

The links between potassium availability and soil exchangeable calcium,magnesium, and aluminum are mediated by lime in acidic soil

Journal of Soils and Sediments - The aims of this study were to investigate the links between potassium (K) uptake by crops and soil K, exchangeable calcium (Ca2+), magnesium (Mg2+), and aluminum...     

An analysis of the resistance of Gossypium arboreum to cotton leaf curl disease by grafting

Cotton leaf curl disease (CLCuD) is a serious constraint to cotton production across Pakistan and north-western India. In the Punjab province of Pakistan at this time CLCuD is associated with one virus, Cotton leaf curl Burewala virus (CLCuBuV), and its associated betasatellite, Cotton leaf curl Multan betasatellite (CLCuMuB). Although some resistance to the virus complex causing CLCuD has been identified in Gossypium hirsutum, this has in the past proven not to be durable. At this time no commercial lines with strong resistance (immunity) to CLCuD are available. Although the cotton fibre produced by Gossypium arboreum is not of the quality required by processors, the species has a number of desirable characters, including resistance to a number of abiotic and biotic stresses, including CLCuD. For this reason there have been efforts to introgress CLCuD-resistance from G. arboreum into G. hirsutum. However, the nature of the resistance of G. arboreum to the viruses causing CLCuD remains unknown. An initial analysis of the resistance was herein conducted by graft inoculation. Graft inoculation of G. arboreum genotype Ravi with scions from severely infected G. hirsutum genotype CIM 496 plants showed that G. arboreum is able to support virus/betasatellite replication and long-distance spread. However, following grafting, only a small number of leaves developing at the time of grafting became mildly symptomatic and symptomatic tissue contained low amounts of virus/satellite DNA, as detected by Southern blot hybridisation; significantly less than the levels seen in G. hirsutum. The symptoms did not spread to the young upper leaves of graft inoculated plants, which contained DNA levels that could only be detected by polymerase chain reaction (PCR) or PCR following an initial amplification by rolling circle amplification–indicating very low DNA levels. The results showed that the resistance of G. arboreum to the virus complex causing CLCuD likely does not involve a mechanism that interferes with delivery of virus by the insect vector. Rather the resistance appears to be due to poor virus replication and possibly interference in short distance (cell-to-cell) spread.     

Comparative efficacy of surface drying and re-drying seed priming in rice: changes in emergence, seedling growth and associated metabolic events

In seed priming, seeds are soaked in a solution of low water potential and dried back to their original weight. This study was conducted to evaluate the comparative performance of different seed priming treatments and to investigate whether re-drying is essential or not? Seeds of fine grain aromatic rice (Oryza sativa L.) cultivar Super-Basmati were subjected to hardening, osmohardening with CaCl₂ and KCl (ψ _s ?1.25 MPa) each for 24 h (one cycle), and hydropriming and ascorbate priming (10 mg L^?1) for 48 h. Seeds were primed in two sets. In one set after each treatment, seeds were given three surface washings with distilled water and dried back near to original moisture contents with forced air. In the other case, after surface washings with distilled water, seeds were surface dried using blotting paper and sown immediately. All the priming treatments improved the emergence, seedling growth and reserve metabolism. Use of surface drying was more effective for rice seed invigoration, as evident from earlier and synchronized seedling emergence. Moreover, shoot and root length, seedling dry weight, root score, α-amylase activity, soluble sugars and dehydrogenase activity were also improved, although germination percentage and leaf score were similar from both strategies. Results suggested that surface drying, rather than re-drying close to original weight, was more effective, while among the treatments, osmohardening with CaCl₂ was the most effective. Increasing rice production with judicious use of water is need of the day, and aerobic rice cultivation is an attractive alternative for this purpose. However, poor and erratic stand establishment is one of the major hindrances in its wide scale adoption. In this regard, seed priming techniques are pragmatic approaches to achieve proper stand establishment in the new rice culture. They help in improving seedling density per unit area under optimal and adverse soil conditions and may be opted to improve the performance of aerobic rice.     

Prevalence of Salmonella associated with chick mortality at hatching and their susceptibility to antimicrobial agents

The prevalence of Salmonella associated mortality at hatching was investigated in three hatcheries in Jos, central Nigeria. Their susceptibility to antimicrobial agents was also evaluated. S. Kentucky and S. Hadar were isolated. While half of the isolates were from internal organs, 26.7% came from meconial swabs of dead-in-shell embryos, 17.8% from intestinal samples and 4.4% from egg shells. S. Hadar is known to colonise only the gut and is classified as non-invasive, but in this study 82% were obtained from internal organs which suggests that infections with this serotype may also cause invasive disease. Antimicrobial susceptibility tests showed a high prevalence of antimicrobial resistance in the study area with complete resistance to gentamycin, enrofloxacin, nalidixic acid, tetracycline and streptomycin and substantial resistance to triple sulphur and ciprofloxacin. Six multiple resistance profiles were recorded with a high level of multiple resistance to quinolones. Quinolone resistance has implications for veterinary and human therapy as their misuse in poultry could lead to the emergence of resistant animal and zoonotic pathogens.     

Farmers’ attitudes towards pesticide labels: implications for personal and environmental safety

The label of pesticide containers is a major source of information for the use of pesticides, but research on whether farmers use this information is scarce. A survey of small-scale cotton farmers was conducted in the area of Punjab, Pakistan, to study attitudes related with the use of pesticide labels. The majority of the farmers (97%) stated that they were using pesticide products purchased in their original containers and accompanied by written information for use. However, 73% of the farmers reported that they usually do not read this information. Elderly, less educated, and experienced farmers in chemical pest control, but without previous training, were found to be less likely to read the labels. A large part of the farmers (34%) stated that they primarily rely on information of pesticide retailers for pesticide use, while nearly four out of ten said they usually rely on other sources of information or their own experience with pesticides. A sizeable proportion of the farmers (9%) mentioned that there is no need to receive information on such issues. Effective pesticide risk communication conveyed through label information is important so that potential risks from pesticide handling may be mitigated at the point of use.     

Deltamethrin resistance in the cotton mealybug, <Emphasis Type="Italic">Phenacoccus solenopsis</Emphasis> Tinsley: Cross-resistance to other insecticides,fitness cost analysis and realized heritability

The cotton mealybug, Phenacoccus solenopsis Tinsley (Homoptera: Pseudococcidae) is a devastating pest that cause rigorous damage to the number of crops through feeding, managed by using various insecticides. To assess the risk of resistance and design a strategy for resistance management, a field collected population of P. solenopsis was selected with deltamethrin in the laboratory for six generations to investigate the cost to its fitness and to examine cross resistance to different insecticides. Bioassay results at G₈ showed that the deltamethrin selected population (Delta-SEL) developed a resistance ratio of 100-fold compared to that of the unselected population (UNSEL). The deltamethrin resistance population exhibited strong cross-resistance to acetamiprid and lambda-cyhalothrin, but no cross-resistance to profenofos when compared to that of the UNSEL. The relative fitness of the Delta-SEL population was 0.37, with considerably lower survival rates from crawler to second instar, fecundity, hatchability, number of next generation nymphs, net reproductive rate and biotic potential compared with that of the UNSEL. The cost of fitness associated with deltamethrin resistance was evident in the Delta-SEL population. The present study provided useful information for management strategies to overcome development of resistance.     

Evaluation of immune responses induced by SAG1 and MIC3 vaccine cocktails against Toxoplasma gondii

The aim of this study was to evaluate the immune responses of a SAG1 and MIC3 vaccine cocktail in BALB/c mice. Ninety-six BALB/c mice were randomly divided into eight groups, including three plasmid DNA vaccine groups (pcDNA-MIC3, pcDNA-SAG1, pcDNA-MIC3+pcDNA-SAG1), three recombinant pseudotype baculovirus vaccine groups (BV-G-MIC3, BV-G-SAG1, BV-G-SAG1+BV-G-MIC3) and two control groups (PBS and BV-G-EGFP). All groups were immunized intramuscularly twice at three-week intervals. The production of anti-Toxoplasma gondii lysate antigen (TLA) antibodies, lymphoproliferation, levels of IFN-γ, IL-4 and IL-10 and the survival time were monitored after vaccination. The results showed that immunization of BALB/c mice with MIC3 and SAG1 vaccines stimulated both the cellular and humoral immune responses with the production of anti-T. gondii TLA antibodies. The vaccine cocktails of pcDNA-MIC3+pcDNA-SAG1 or BV-G-SAG1+BV-G-MIC3 induced significantly higher immunogenicity than a single-gene vaccine (P<0.05). Splenocytes from the immunized mice significantly proliferated in response to the TLA and released interferon (IFN)-γ (P<0.05). However, the levels of IL-4 and IL-10 in the sera of the immunized mice were not significantly different from those of the controls (P>0.05). Immunization with the vaccine cocktail (BV-G-SAG1+BV-G-MIC3) in mice significantly prolonged survival (50%; P<0.05) against a lethal challenge of T. gondii (RH tachyzoites), while all mice in the other immunized groups and control groups died within 20 and 4 days post-infection, respectively. Furthermore, the recombinant pseudotype baculovirus vaccines induced better immunogenicity than the plasmid DNA vaccines (P<0.05). These results suggest that an excellent vector-mediated vaccine cocktail strategy might be used to develop a new generation of vaccines against T. gondii infection.     

Estrus response and follicular development in Boer does synchronized with flugestone acetate and PGF2α or their combination with eCG or FSH

The effects of different estrus synchronization techniques on follicular development and estrus response were studied in 81 nulliparous Boer does. The does were divided into nine groups. Eight of the nine groups were synchronized with prostaglandin F2-alpha (PGF(2α)) or flugestone acetate (FGA) or their combinations, and the ninth group was a control group. In addition to the above combinations, four of the eight synchronized groups were given 5?mg follicle-stimulating hormone (FSH) and the remaining four groups were administered 300?IU equine chorionic gonadotrophin (eCG). Posttreatment follicular development was monitored until ovulation occurred using a real-time B-mode ultrasound scanner (Aloka, 500 SSD, Japan), with a 7.5-MHz transrectal linear probe. All the does from the synchronized groups that were given eCG exhibited oestrus while only 88.9% of the does synchronized with FSH showed estrus. The estrus response was observed to be the least among the does synchronized with PGF(2α) + FSH (33.3%) combination followed closely by the FGA + FSH (42.9%) combinations. It was observed that the combinations of FGA + PGF(2α) + FSH resulted in increased percentage of estrus response, duration of estrus, and ovulation. The number of follicles was higher (P?相似文献   

转基因育种技术在菊花性状改良中的应用进展

 自1989 年发现了菊花对农杆菌浸染的敏感性,农杆菌介导转化法已成功应用于菊花花色、花期、株形、抗病虫及耐非生物胁迫等性状的改良中。从影响菊花遗传转化效率的农杆菌菌株类型、外植体选用、辅助添加剂的使用以及抗生素筛选等几方面阐述了菊花遗传转化技术研究的进展和应用现状,对菊花分子育种性状改良和重要功能基因发掘等研究进展进行综述,并对菊花转化效率改善途径的探索和环境友好型转基因新技术研发前景提出展望,以期为菊花分子育种提供参考。