THE SCIENTIFIC JOURNAL OF AGRICULTURE (SJA)
Year:2008 | Volume:30 | Issue:4-A|Papers Count:17

Date palm (Phoenix dactylifera L.) is a dioecious plant in which artificial pollination is an essential cultural practice to obtain satisfactory fruit set. Use of viable and high quality pollen grains is the most important factor in fruit production and breeding programs. This research was conducted to study the in vitro pollen germination of three male date cultivars under varying concentrations of sucrose, boric acid and calcium nitrate. The experiment was implemented as a factorial in completely randomized designs with three replications. Experimental factors were three male date cultivars. (Ghanami, Samsmavi and Gheibani), four concentrations of boric acid (0, 50, 100 and 200 mg/Lit), three concentrations of calcium nitrate (0, 200 and 300 mg/Lit) and two sucrose concentration (15% and 25%) in modified Brebaker and Kwack medium. Also a comparison was made between two methods of viability test: in vitro germination and staining with acetocarmine. The results showed that in vitro germination is more effective and precise method for viability test of male date pollens and maximum germination was seen under 50 mg/Lit boric acid, 200 mg/Lit calcium nitrate and 15% sucrose concentration in the medium. Also Samsmavi and Ghanami cultivars had the maximum and minimum viability with 81.8% and 58.4% pollen germination, respectively.

Hulless barley with high quality and high nutritious value and higher test weight than the common barley could play an important role in compensation requirements of grain production in our country. This research was conducted in experimental of field of Shahid Chamran University, Ahvaz, Iran. The experiment was an augmented design in 6 blocks including 54 genotypes and three common barley varieties as cheek. The field soil was sandy loam, with pH=7.7 and EC=3.6 mmhos/cm. Each genotype planted in 1.35 m^2, 3-4 cm depth in six rows with 1.5 meter length between rows was 15 cm. During the growth period, lodging percentage, rust disease, days between emergence to heading and to maturity, plant height and tillering coefficient were measured. Yield, yield components, and some characters of these genotypes were evaluated after correction for incomplete block effects. The highest grain yield was 5999 kg/ha for genotypes number. One of the checks was also in the same group. Because of low percentage of fiber and high protein content, in naked barley compared to common barley, the results show that 12 genotypes had more than 4000-kg/ha grain, so they were preferred to common barley. As a result of this experiment, these genotypes have been selected as the best genotypes.

This trial was conducted to investigate the effects of fattening periods on growth and carcass characteristics of Turkey-Ghashghaii male lambs. 80 lambs with age of 90±7 days and with an average body weight of 23.1±2.5 kg were used. At the end of each period of 60, 90, 120 and 150 days, 16 lambs were slaughtered for evaluating the carcass characteristics. Results indicated fattening period showed a highly significant effect (P<0.01) on body weight and feed conversion ratio, whereas the effect on daily gain, carcass efficiency and meat percentage was P>0.05. There was a significant effect on fat and bone percentages (P<0.05) while increasing fattening period and fat percentage increased but bone percentage decreased. The highest carcass meat (49.8%), fat (17.9%) and bone (19.2%) were found after 120, 150 and 60 days respectively, and the lowest (47.1, 13.7 and 13.9%) were. found after 150, 60 and 150 days respectively. By increasing fattening period, fat-tail percentage increased and the highest (20.1%) and the lowest (17.4%) respectively were found after 150 and 60 days. The eye muscle area in different fattening period was 11.07, 14.23, 15.50 and 15.73 cm2 respectively and was highly significant (P<0.01) for 60 days fattening compared with other periods. Effect of fattening period on carcass composition was significant. With increasing fattening period the percentage of moisture, protein and ash decreased but fat percentage increased. The best period for gaining meat as a most important factor was 90 days.

Azotobacter chroococcum is a free-living N2 fixing bacterium potentially beneficial for plant growth. Apart from fixing nitrogen asymbiotically, this bacterium has also the ability to synthesize and secret different kinds of plant growth promoting compounds essential for plant growth, therefore it is considered as Plant Growth-Promoting Rhizobacteria (PGPR). In this study, the potentials of native strains of Azotobacter chroococcum to promote plant growth was evaluated using in vitro tests. First, soil samples were taken from the rhizosphere of irrigated wheat in 63 wheat fields of Chaharmahal from Bakhtiari province and then native strains of Azotobacter chroococcum were isolated, identified and counted. Second, the purification of Azotobacter chroococcum isolates were carried out, and in vitro tests including the ability to produce indole-acetic acid (IAA), siderophore, hydrogen cyanide (HCN), the ability to solubilize mineral and organic insoluble phosphates and nitrogen fixation were conducted. Results showed that Azotobacter chroococcum population varied among the wheat fields, being the highest in Choghakhort wheat fields and the lowest in wheat fields of Jooneghan area. Results indicated that most isolated strains were capable of producing IAA, siderophore, and HCN, and fixing nitrogen. However, they were not able to solubilize mineral and organic phosphates. Therefore, the production of IAA and nitrogen fixation would be the major function of native isolates, and thus their presence in the rhizosphere could improve wheat growth and yield. Overal, based on the obtained results in this study, only some strains of Azotobacter chroococcum native to wheat fields of Chaharmahal in Bakhtiari are recogilized as PGPR.

Pulvinaria aurantii (Cockerell) is the most important citrus pest in Mazandaran province, Iran. Economic injury levels for 2nd generation of P. aurantii were studied on Thomson novel in Sari (North of Iran). A commercial orchard of Thomson navel with fifteen rows, each containing between 60 and 70 trees, during 2002 and 2003. For determination of EIL, trees of the orchard, according to infestation level of Fumagin and the number of 1st and 2nd instar of nymph, were divided to 4 groups (no infestation, low infestation, medium infestation and high infestation). Among trees of each group, 12 trees were selected randomly. The number of nymphs and average of clean fruit yield were recorded and then regression relation was established between them. This regression relation was significant (p<0.001) and negative. The results showed that P. aurantii not only the mean clean fruit yield but also the mean total fruit yield (infested and no-infested fruit with Fumagin) were significantly reduced (p<0.01) in high infestation. EIL of P. aurantii was verified from 16 to 19 (nymphs/24 leave/trees) depending on the product prices and control action costs.

For desilting the deposited sediment, flushing method could be used in two different methods: Free Flushing and Pressure Flushing. In the latter, the previously deposited sediment would be flushed from the reservoir by opening of the outlets, and typically the scour cone "Flushing Cone" developed near the outlet in the reservoir. The scour cone geometry was influenced by many factors including water depth on the bottom outlets, outflow discharge through the bottom outlet, outlet geometry, characteristic of the sediments which deposited in the reservoir, etc. In this study, the effect of the outflow discharge through the bottom outlet and the water depth on the bottom outlets were investigated by non-cohesive sediment with d50=0.27mm. For this purpose, laboratory experiments were performed, so a physical model was constructed in the Hydraulic Laboratory at the faculty of Water Engineering and Science, University of Shahid Chamran, Ahvaz, Iran. The result of this research showed the flushed sediment increased with the decrease of reservoir's water depth, as the reduction of water depth equal to 31.5% caused the scour cone volume and its length to increase to 41.5% and 14.5%. Also the decrease of 76.6%, outflow discharge caused the scour cone volume and its length decreased to 20.3% and 49.9% respectively. Also based on the satirical analysis, non-dimensional relations for determining the flushing cone volume and its length are represented.

Fried-Combernous and Brigham models are two of the important models for nonreactive contaminant transport in saturated, homogeneous porous media under steady-state uniform flow. These models are proposed for computing dispersivity in long and short distances respectively. In this research, dispersivity of coarse and medium homogeneous sands is investigated by these two models. Experiments were. carried out in a rectangular laboratory- scale Plexiglass tank, 0.72 m long, 0.1 m wide and 1.2 m high. A solution containing 8 g/l (EC=14 dS/m) sodium chloride concentration was used as the non-reactive contaminant. Experiments were carried out with soil thicknesses of 0.1 m in sequence up to a final thickness of 1 m. A total of 110 dispersivity values obtained from using. these models were compared. The results indicated that for long travel, dispersivity obtained from these two models are equal for homogeneous sands used in these experiments. Therefore we can conclude that Brigham model can be used for long travel case with the same accuracy as Fried-Combernous model. Also in long travel distance, the dispersivity values calculated by Fried-Cambernous model with the pollutant velocity and actual velocity are equal. The results indicated that as in short travel distances, with decreasing values of b, time to reach 0.5 C/C0 occurred at less pore volume. But in long travel distances, time to reach 0.5 C/C0 occurred at more than one pore volume.

In a field experiment conducted at experimental farm of shiraz agricultural college in 2003, effects of six various tillage and planting methods on emergence of irrigated wheat seedlings were evaluated. The ordinary methods (treatments) were composed of broadcasting + disk + furrower (T1), Simple grain drill + furrower (T2), Simple grain drill and flat planting (T3) and the new methods were: Furrower + simple grain drill (T4), furrower + new grain drill (their openers fallow furrows) (T5) and furrower + new grain drill + bedshaper (T6). A randomized complete block design with three replications was used. Grain yield and yield components including number of fertile shoots, number of grains per spike, 1000 grain weight and harvest index were evaluated. The results showed that there were significant differences in the number of grains per spike and also grain yield among the treatments. The T3 treatment, compared to the others, had the minimum seed spacing mean, maximum emerged seed mean, maximum number of fertile spikes and maximum grain yield. The T6 treatment indicated minimum fertile spikes, maximum mean number of grains per spike, maximum 1000 grain weight and maximum harvest index. In almost all cases, T3 and T6 were preferred to the other methods, and could be recommended for similar conditions to this experiment. The T3 treatment (5258.7 kg/ha) showed maximum grain yield.

In this study, a total of 179460 monthly test day milk records (thrice a day with 10 test day records for each cow) obtained from 17946 Iranian Holstein cows at first lactation and distributed in 287 dairy herds and calved between 1986 and 2001 were used to estimate genetic parameters of milk yields during the lactation period. An animal model implementing covariance function methodology (orthogonal Legendre polynomials) was used for genetic analysis of monthly test day milk records. The results revealed that milk production of the second half of the lactation is on average more heritable than the first half of the lactation. The lowest and highest heritabilities were found for first (0.063) and seventh (0.299) month of lactation, respectively. The results also showed that genetic correlations among monthly test day milk yields decreased when the interval between them increased so that milk yields at first and last month of the lactation period had the lowest genetic correlation (0.398).

A study was conducted to evaluate the efficacy of c1inoptiloliteto reduce the effecte of aflatoxin in diets of broiler chicks. In this study 900 day-old male chicks were used in experimental as factorial (completely randomizd desing) with three levels of clinoptilolite (0, 3 and 5%) and three levels of aflatoxin (0, 1 and 2ppm) from 1 day to 7 weeks of age. The result showed that the live weight, carcass weight and weekly weight gain were higest (2215, 1583, and 53.8 respectivley) for broilers fed ration 7 (containing 5 percentage clinoptilolite and 0 ppm aflatoxin) and were lowest for ration 3 containing 0% clinoptilolite and 2 ppm aflatoxin (1571, 1043 and 37.25 respectivley).The liver weight, feed conversion ration and mortality percentage were higer for ration 3 (45.8gr, 2.23 and 15.9% respectivley) and were lower for ration 7 (40.08gr, 1.78 and 6.98% respectivley) than the other ration. The highest feed intake related to diet 4 contains three percentage clinoptilolite and 0 ppm aflatoxin (4060gr) and the lowest feed intake was related to diet 3 (3633gr). In general, the results showed that aflatoxin in level higher than 1ppm resulted in reducing of broiler performance and increasing feed conversion ratio. The usage of clinoptilolite in diet can reduce the effects of aflatoxin and in the condition of this experiment the level of 5% clinoptilolite was better.

Sorghum is resistance to unsuitable environment condition such as low fertility of soil and drought. It can be cultivated in wide range of fields in south of Khouzestan. This study was conducted during 2002 and 2003, in order to determine suitable sowing date of grain sorghum cultivars on a clay soil in Khouzestan agricultural research center (Shawoor station), an experiment was carried out as split plots in randomized complete blokes with four replications. Main plots included five sowing date levels, starting from 21 May with 15 days intervals and subplots included three cultivars of grain sorghum (Payam, Kimiya and Sepideh). Evaluated indices were contained grain yield, fertility percentage, thousand kernel weight (T.K.W), raceme length, raceme width and number of spiklet per spike. The result showed that there were significant differences (P£0.01) among sowing dates and treatment interaction for grain yield, fertility percentage and T.K.W. Also there was not significant (P£0.05) for raceme length, raceme width and number of spiklet. Cultivars differences for yield and other indices were significant (P£0.01).Sowing dates 15 May and 22 July treatments was better than others for grain yield, fertility percentage and T.K.W. Sepideh variety was better than two other cultivars for grain yield and other indices. The highest grain yield (4.203 ton/ha) obtained from Sepideh cultivar and sowing date at 22 July. Consequently, it is recommended that Sepideh cultivar can be used as a best cultivar for cultivating during 7-16 July in Khouzestan province.

During the period of 2005-2006, 80 isolates of Fusarium proliferatum, one of the major casual agents of Knife-cut disease of sugar cane in Khuzestan province, were recovered. All isolates were examined for their pathogenicity and vegetative compatibility groups (VCGs). Results revealed that all isolates were pathogenic on sugar cane. For diversity studies, nit mutants were generated from all isolates using PDC containing 3 & 5% KCL03 and Czapeck medium containing 3% KCL03. Collectively, 497 nit mutants were generated. Phenotype of the mutants were determined based on their growth on basal medium containing one of the following salts: sodium nitrate, sodium nitrite, hypoxanthin and ammonium tartrate as a sole nitrogen source. Among the generated nit mutants, 45.3%, 19.7% & 35% were nit1, nit3 & nitm respectively. No vegetative self-incompatibility was observed in the isolates. Complementation tests between nit mutants that were carried out on minimal medium revealed that the isolates belonged to 27 vegetative compatibility groups. No specific relation was found between VCGs & pathogenicity of the isolates. No specific relation was either found between VCGs & geographic origin of the isolates.