Journal of Agricultural Science and Technology
Volume:4 Issue: 3, Oct 2002

Laboratory experiments were conducted to understand the influence of host-finding behaviour of Apanteles subandinus Blanchard and Orgilus lepidus Muesebeck, two endoparasitoids of the potato tuber moth (PTM) Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), in a successful biological control of the pest. Responses of the two parasitoids to their host and to three host plants of the PTM were investigated in a wind tunnel individually. The results suggested that host-finding by both parasitoids is stimulated by a combination of chemicals. Females of both species discriminate between the volatiles of a mechanically damaged plant and those of PTM larvae-damaged plant. The combination of odours originating from plant host on which the host is feeding play a crucial role in the foraging behavior of these parasitoids. Developmental experience during larval stages and experience of adults to host plant influence their foraging for host. The implications of parasitoid response towards plant volatiles and their importance in biological control are discussed. Additional experiments are necessary to isolate and identify the nature of the volatile chemicals released from the host-plant complex and use them to improve the biological control of the pest.

The primary purpose of this study was to assess farmers'' Sustainable Agricultural Practice Needs (SAPN) as determined conversely by their level of technical knowledge and understanding of sustainable corn farming practices. The population of this study consisted of all corn growers in Fars, a southern province of Iran. A questionnaire was developed to gather the information required from 159 randomly selected farmers. Farmer’s demographic and professional characteristics, including their level of technical knowledge, access to information sources, and level of mechanization were considered to be independent variables of the study. The SAPN was the dependent variable of the study. The result showed that a considerable numbers of farmers (46%) have a "high" level of needs concerning sustainable agricultural practice. The farmers'' level of technical knowledge showed to have a substantial (r= -0.64) and negative association with their SAPNs. Multivariate linear regression analysis indicated that 49.3% (R2=0.493) of the variance in SAPNs could be explained by the farmers'' age, their access to information sources, and their level of technical knowledge. This implied that a substantial amount of variability (about 51%) in SAPNs are explained by other variables that were not studied in this research. Further study is needed to determine factors affecting SAPNs and extend of the impact.

An experiment was conducted to determine the dietary digestible lysine requirement of male and female broiler chickens (Arian) during the period from 6 to 21 days posthatching. An amino acid-fortified basal diet containing corn and soybean meal as intact protein sources provided 20 % CP, and 3200 kcal AMEn / kg. In this experiment 150 male and 150 female chicks were allocated on the basis of BW to 12 treatments in a factorial arrangement (two sexes at six digestible lysine levels) with five replications of five chicks each in a completely randomized design (CRD). The digestible lysine levels fed were 0.85, 0.95, 1.05, 1.15, 1.25 and 1.35%. The growth rate and feed efficiency of birds fed the basal diet fortified with a surfeit level of l-Lysine-HCl were equal to those of birds fed a corn-soybean meal positive control diet. Average body-weight gain (ABWG) and gain: feed (GF) responded quadratically (P<0.05) to incremental dietary lysine addition. Subjecting the growth data to broken-line analysis indicated that the digestible lysine requirement for maximum body weight gain was 1.075% for males and 1.049% for females. The lysine requirement for maximum feed efficiency was 1.179% for males and 1.149% for females. Male chicks required a higher level of dietary lysine than females for both maximal ABWG and GF. Regardless of sex, 8.8% more digestible lysine (percentage of diet) was required for maximal GF than that needed for maximal ABWG.

A solid state fermentation method was developed for the production of citric acid from date pulp (obtained of date syrup production from the process) by Aspergillus niger PTCC 5010. Poor yield was obtained when potassium ferrocyanide treated date pulp were used as substrate, but methanol at a 3-4% concentration markedly increased the formation of citric acid from the waste. The optimum range of pH and moisture for citric acid production were 3.5-4.5, and 70-80% respectively. This method produced about 168g citric acid per kg of date pulp under optimum conditions. On the basis of reducing sugar consumed, the yield was 87% within eight days.

The antimicrobial effects of essential oil isolated from Myrtus communis L. against Escherichia coli, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Klebsiella pneumoniaee, Bacillus subtilis, Bacillus licheniformis, Candida albicans and Saccharomyces cerevisiae were studied. The disc diffusion method was used to evaluate the zone of microbial growth inhibition at various concentrations of the oil. The minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) of the oil were determined. The oil was found to have an antimicrobial effect. Kinetics of microbial destruction exhibited that the oil could kill microorganisms within 45 minutes of exposure. GC and GC/MS analysis of the oil revealed 32 components. The major components were α-Pinene (29.4%), Limonene (21.2%), 1,8-Cineole (18%), Linalool (10.6%), Linalyl acetate (4.6%) and α-Terpineole (3.1%). The high monoterpenes hydrocarbons such as α-Pinene and Limonene seem to contribute to the strong antimicrobial activity of Myrtus communis L. Further research on antimicrobial effects of essential oils with a view to substituting the common chemical compounds is promising.

Two barley (Hordeun vulgare L.) genotypes, Radical and Cwb, with good to moderate levels of resistance to powdery mildew were crossed with a highly susceptible cultivar (Afzal) to determine the genetics of resistance. The parents, Fl, F2 and F3 generations of each of the two crosses, were evaluated for powdery mildew resistance in the glasshouse and field at the College of Agriculture in Karaj during 2000. The x2 analysis of the segregating ratios in the F3 generations indicated that the resistance was controlled by one gene at seedling stage and by two or three genes at adult plant stage in Cwb and Radical, respectively. Radical showed a higher level of resistance than the Cwb, therefore, it is a better source of resistance to powdery mildew.

An efficient system has been developed for the reproducible regeneration of plants from cell suspension-derived protoplasts of the two commercial Iranian Japonica rice cultivars Tarom and Khazer. Friable embryogenic calli were used for cell suspension initiation and protoplasts were isolated from both varieties. When embedded in agarose, protoplasts failed to divide. However, sustained divisions were obtained by using nurse cells of Lolium moltiflorum. Plant regeneration was 21.1% and 10.5% for Tarom and Khazer, respectively. Somaclonal variation was observed amongst regenerated plants, 16.2% of regenerants were tetraploid, and the rest were diploid.

CaMV 35S promoter activity has not been analysed in different stages of growth in oilseed (B. napus). Higher plants lack intrinsic β-glucuronidase activity, thus enhancing the sensitivity with which measurements can be made. The binary transformation vector pVW432 (Buchanan-Wollaston, unpublished), carrying the GUS gene fused to the CaMV 35S promoter, was used to test transformation efficiencies and promoter activity in B. napus. The effect of different components of culture media was tested. Having studied different antibiotics, two selectable markers, and Agrobacterium strains, the combination of 500 mg/l carbenicillin with 25 mg/l kanamycin was the optimum level for inhibition of Agrobacterium strain C58pGV3101 and the selection of transformants, respectively. Different developmental stages of plants were analysed by protein assay. DNA extraction and PCR amplification confirmed the presence of the gene. High level of β-glucuronidase activity, hence CaMV 35S promoter activity, was observed for one of the transgenic plants. The β-glucuronidase activity altered from maturity to senescence indicating that the CaMV 35S promoter has different activity at different developmental stages in B. napus. Therefore, the growth stage of B. napus may influence the CaMV 35S promoter activity.