Showing 67 results for Growth
N. Mehrdad, M. Alikhani, G. R. Ghorbani,
Volume 8, Issue 2 (7-2004)
Abstract
In a completely randomized design with a factorial arrangement (3× 5× 3), three fistulated sheep with an average body weight of 47.5 ± 2.5 kg were used to determine the effect of cutting and growing stages (no bloom , early bloom and full bloom) on chemical composition and In situ degradability of alfalfa (Medicago sativa). Nylon bags (50 µm pore size) were filled with 3.5 g of each sample and suspended in the rumen before morning feeding and incubated for seven different times (0, 2, 4, 8, 16, 24 and 48 h). The results showed that alfalfa at no bloom stage had the highest crude protein and the lowest crude fiber content. The third – cut alfalfa had the highest degradability of dry matter and organic matter. Extent of degradability depended on crude fiber and solubility. During growth stage, the protein, soluble material and degradability levels decreased while crude fiber, neutral detergent insoluble crude protein (NDICP), and acid detergent insoluble crude protein (ADICP) increased. The amount of ADICP was an estimate of unavailable crude protein in the rumen. Although the rate of organic matter degradation was maximum in full bloom, no significant difference was observed between the three stages of growth. Effective degradability (ED) of crude protein was significantly different among stages the growth (p<0.05). Effective dry matter degradability (EDDM) with a passage rate of 6%/h was significantly higher in the third cutting of alfalfa. The results of this study showed that first cutting and full bloom alfalfa had the lowest and fifth cutting and no bloom had the highest CP levels. The effect of cutting and growing stages on degradability parameters was variable and did not allow any firm conclusions to be made.
E. Ebrahimi, J. Pourreza, S. V. Panamariov, A Kamali, A. Hosaini,
Volume 8, Issue 2 (7-2004)
Abstract
A 3×4 factorial experiment was conducted for 45 days to determine the effects of diets containing different levels of protein and fat on growth of fingerlings Beluga (Huso huso L.1758). Twelve different diets were formulated with 3 levels of protein (45,50 and 55) and 4 levels of oil including fish oil and sunflower oil (0.5 ,4 , 8 and 12). 1260 Beluga fingerlings with an initial body weight (IBW) of 2.2 gram, after adaptation to the experimental conditions, were selected and stocked randomly into 36 fiberglass tanks (100 water volume) at 35 fish per tank, and fed on experimental diets for 45 days. Two ways analysis of variance showed that the percentage of body weight increase (%BWI), specific growth rate (SGR),protein efficiency ratio (PER), food concumpsion ratio, and productive protein value (PPV) content were significantly (P<0.05) affected by different protein and fat levels. Fishes fed on diets No.3 (containing 45% protein and 14 % lipid) and No.8 (containing 50% protein and 17 % lipid) showed the highest increase in body weight percentage, the best specific growth rate, protein efficiency ratio, and lowest food concumption ratio. Besides, the highest productive protein value was observed in diet No.2 (45% protein and 10.5% lipid) and diet No.3 (45% protein and 14 % lipid).Comparison of chemical composition of examined fish corps indicated a significant difference in their protein and lipid contents (P<0.05). However, the composition of the diet, revealed no significant changes on the dry matter and ash content of the body. Based on the findings of the present study 45-50% dietary crude protein is recommended for the optimum growth of Beluga fingerling. Moreover, the rate of needed lipid for optimum growth of fingerling range is from 14 to17 percents.
A. Zare Shahneh, H. Sadeghi Panah,
Volume 8, Issue 4 (1-2005)
Abstract
In order to determine the effects of fetal growth rate on plasma concentrations of glucose, triglyceride, total protein, and urea in ewes, this experiment was conducted at Animal Research Station of Tehran University Agricultural College. Sixteen pregnant Varamini ewes were allocated to 4 groups (n=4). During the breeding season, ewes of group 1 were mated by Varamini ram, animals in groups 2, 3 and 4 were mated by Moghani, Afshari and Shall rams, respectively. Because of the different genetic capacities of sires, fetal growth rate was expected to be different in various groups. Ewes in all groups were fed the same ration, so it was expected that differences in fetal growth rates would affect the mobilization of maternal fat and protein storage and blood levels of their metabolites. Blood samples were collected from jugular veins of ewes during the last 8 weeks of pregnancy and first week after lambing.
Plasma levels of glucose, cholestrol, and triglycerid were not different among 4 groups. Total plasma protein in ewes carrying heavier fetuses was lower than in ewes with lighter fetuses (p<0.05). Conversely, plasma urea concentrations in ewes with heavier fetuses were higher than in ewes with lighter fetuses.
F. Shir-Mohammad, N. Mahboobi Soofiani, J. Pourreza,
Volume 8, Issue 4 (1-2005)
Abstract
In order to investigate the effect of phytase and copper supplementaion on growth and carcass composition of common carp (Cyprinus carpio L.), in a completely randomized design with 3 ×2 factorial arrangement with three replicates the experimental diets including three levels of phytase 0, 500 and 1000 (FYT) kg-1 and two levels of copper 0 and 15 mg/kg were tested. Diets contained 0.72 percent total phosphorus. One hundred and forty four carps with a mean weight of 207±23 g were selected and allocated in eighteen cages (8 fish per cage). The experiment was carried out for 8 weeks and 2 weeks for acclimatization. Phytase supplementation caused no significant differences in weight gain (WG), feed conversion ratio (FCR), carcass index (CI), protein efficiency ratio (PER), liver, carcass and blood composition but increased apparent phosphorous digestibility (APD) significantly (P<0.04). Copper supplementation also caused no significant differences in WG, FCR, CI, PER, APD, liver copper, carcass composition, cholesterol (Ch), triglycride (TG), phosphorus of serum but decreased liver fat significantly (P<0.004) and increased high density lipoprotein (HDL) of serum (P<0.02). Interactions between phytase and copper on WG (P<0.01), FCR (P<0.04), PER (P<0.03), liver copper (P<0.02) and TG of serum (P<0.001) were significant. This experiment suggests the presence of antagonistic effect between phytase and supplemental copper. Phytase enzyme improved some parameters of growth and carcass composition of common carp without supplemental copper but addition of copper to the diets with phytase enzyme impaired the improved performance of carp.
M. R. Bahreini Behzadi, F. Eftekhari Shahroudi, L. D. van Vleck,
Volume 9, Issue 1 (4-2005)
Abstract
Data from the birth weight (BW), the average daily gain from birth to weaning (ADG) and the weaning weight (WW) of 1182, 1099 and 1099 lambs were respectively collected and applied to estimate the maternal effects on heritabilities as well as on the determination of the environmental factors. The data were collected from Shahrbabak Sheep Breeding Research Station within five year, from 1993 to 1998. The effects of the year of birth, the age of the dam and its sex on all the traits were significant. The type of birth had no effect on BW but it was significant for the other two traits. Estimates of (co)variance components and genetic parameters were obtained by restricted maximum likelihood, using single and two-trait animal models. Based on the most appropriate fitted model, direct heritability of BW, ADG and WW were estimated at 0.10± 0.06, 0.21 ±0.08 and 0.22± 0.09, respectively. The maternal heritability for the three traits was also estimated at 0.27± 0.04, 0.15 ±0.05 and 0.19 ±0.05, respectively. Direct genetic and phenotypic correlations between BW and ADG BW and WW ADG and WW were estimated at 0.85 and 0.41 0.82 and 0.48 and 0.99 and 0.99, respectively. Ignoring maternal effects in animal model caused overestimation of direct heritability. Thus maternal effects are significant sources of variation for early growth traits and their ignorance in the animal model causes inaccurate genetic evaluation of the lambs.
Y. Fathipour, A. Hosseini, A. A. Talebi, S. Moharramipour, Sh. Asgari,
Volume 9, Issue 2 (7-2005)
Abstract
The biological parameters of cabbage aphid, Brevicoryne brassicae (L.) was studied in the laboratory conditions under the three constant temperatures (20, 25 and 30 ºC), RH 60±5% and a photoperiod of 16:8 (L:D) using 40 first instar nymphs. Among nymphs, 40%, 55% and 10% of them completed their nymphal period in 20, 25 and 30 ºC, respectively and developed to adult stage. In 30 ºC, the most biological acitivities of aphid were disrupted and the most individuals (nymphs and adults) were killed. Most developmental periods, longevity and the amount of reproduction in 20 ºC were significantly greater than other temperatures. In temperatures 20, 25 and 30 ºC the last individual of a cohort died in age of 33, 29 and 16 days, respectively. The life expectancy of cabbage aphid in the first day of experiment was 13.93, 10.50 and 7.19, respectively according to the mentioned temperatures. There was a little difference between net reproduction rates in temperatures 20 and 25 ºC (16.74 and 15.92, respectively). Net reproduction rate was reduced extremely in temperature 30 ºC (1.75). The intrinsic rate of the increase in the temperatures 20, 25 and 30 ºC were 0.187, 0.226 and 0.042, respectively. The results indicated that 25 ºC was the optimal temperature for biological activities of B. brassicae and its highest population growth was observed at this temperature.
E. Khaleghi, A. A. Ramin,
Volume 9, Issue 3 (10-2005)
Abstract
Due to the existence of salinity and high temperature and sensitivity of some plants in most regions of Iran, especially in Khoozestan, there are a lat of difficulties in the planting and husbandry of lawn. Therefore an experiment was carried out under field conditions, to investigate the effect of seven levels of salinity as: Karun river water with EC of 1.09, distilled water (0.01) and irrigation with hand made salinity of 3, 6, 9, 12 and 15 dS/m on the growth and development of three types of lawn namely: Lolium perenne L. cultivar Barball, Festuca arundinacea cultivar Kentaky-31-C and Cynodon dactylon cultivar Primo in the form of a 7×3 factorial with a completely randomized design in 3 replication. A number of leaves on the main shoot and tiller, fresh and dry weight of leaves, leaf area and a number of tiller per plant were recorded. According to the results, it was revealed that the effect of salinity, Genus and interaction were significant (P<0.05) on growth parameters. In all salinity levels, Cynodon dactylon, in comparison to the other two genus displayed the highest rate of growth, while between the two other genus there were no significant differences. In addition, it was revealed that the number of leaf on the tiller and main shoot in Cynodon dactylon at a salinity of 15 dS/m was 5.1 and 4, respectively. Whereas in others, no leaves were initiated at this level of salinity. It was also appeared that at salinity of 15 dS/m, the growth of leaf area, the fresh and dry weight of leaves greatly decreased in Lolium perenne and Festuca arundinacea, while Cynodon dactylon still had growth ability. It was concluded that the number of tiller per plant and high of the plant was less affected by salinity, compared to the other growth parameters in all of genus.
F A. Frouzandeh Shahraky, M. R. Khajehpour,
Volume 9, Issue 4 (1-2006)
Abstract
Under irrigation and in double-cropping system, a large amount of plant residue remains after harvest that along with the limited time for residue decomposition and complete seedbed preparation, necessitates reduced tillage and special residue management. In the present study, the effects of various seedbed preparation methods on vegetative growth, yield components and seed and oil yields of sunflower (Euroflor hybrid) were studied in a barley-sunflower cropping system during 2001 at the Agricultural Research Station, Isfahan University of Technology. Three residue management treatments (standing, partly removed and burned) along with five tillage systems (moldboard + disk chisel + disk disk moldboard and furrower as the minimum tillage) were laid out in a split-block design with three replications. Burning residue treatment significantly increased plant dry weight at various developmental stages and also head diameter. Number of seeds per head, 1000 seed weight, harvest index, and oil yield were non-significantly higher in the burned residue treatment. Seed yield was significantly higher in the burned and partly removed residue treatments. Moldboard + disk and chisel + disk treatments significantly produced higher plant dry weight at various developmental stages, head diameter and seed yield. Number of seeds per head, 1000 seed weight, harvest index, and oil yield were non-significantly higher in these treatments. Minimum tillage ranked the lowest for these traits. The results of this experiment indicate that chisel + disk treatment with the partly removed residues might be an appropriate seedbed preparation method in a barley-sunflower double planting under conditions similar to this experiment.
M. Haghighat Afshar, M. Babalar, A. Kashi, A. Ebadi, M. A. Asgari,
Volume 10, Issue 3 (10-2006)
Abstract
Some strawberriy cultivars (Fragaria x ananassa Dutch. cv. Aliso, Selva, Gaviota and Camarosa) were grown hydroponically with five NH4:NO3 mM concentration ratios (0/6 (S1), 0.25/6 (S2), 0.5/6 (S3), 1/6 (S4), 2/6 (S5) and constant nitrate concentration in three replicates for two seasons: Summer and Winter, in greenhouses of Agriculture Faculty of Tehran University. The results are reported as Follows: In summer shoot dry weight and shoot/ root ratio were highest in 0.25 and 0.5 mM NH4-N and were constant in remaining solutions with higher ammonium concentration. Increasing ammonium concentration resulted in decreasing the root dry weight. Aliso and Selva had the highest shoot and root dry matter respectively. Gaviota had the highest runner. In winter, shoot dry matter was highest in plants grown in S5 solution. Increasing ammonium from 0 to 0.5 mM decreased fruit yield but more ammonium in S4 and S5 solution increased yield. Root and fruit dry matter were highest in Selva. Yield and Fruit fresh weight were highest in Gaviota. Camarosa had the highest shoot dry weight. In summer shoot dry weight was significantly higher than in winter. Due to the high yeild, commercial use of the S5 solution and the cv. Gaviota is recommended.
J. Shakarami, E. Bazgir, M. Feizian,
Volume 10, Issue 3 (10-2006)
Abstract
To search for reproducible and environment-friendly antifungal agents, essential oils of five plant species including Myrtus communis, Mentha aquatica, Vitex agnus-castus, Thymus daenensis and Artemisia aucheri were studied for their inhibition effects on the mycelial growth of plant pathogenic fungi including Fusarium oxysporum, Pythium ultimum, Rhizoctonia solani and Gaeumannomyces graminis. The experiment was conducted using a completely randomized design of factorial experiment including three essential oil concentrations and three replications at 25±2 ºC on PDA. Results revealed that R. solani with 48.83 and P.ultimum with 89.62% mean of mycelial growth inhibition were the most resistant and the most susceptible fungi to the essential oils, respectively. The essential oil of M. aquatica and T. daenensis with 93.70 and 92.74% mean of mycelial growth inhibition showed the most inhibition effect and V. agnus-castus with 33.88% was the least mycelial growth inhibitor. The essential oil of M. aquatica and T. daenensis at 20 µl/petri plate (9 cm. in diameter) completely inhibited the mycelial growth of the tested fungi. Considering the high antifungal effect, and low human and environmental hazard of essential oils, it seems that the essential oils may be used for the control of plant pathogenic fungi, or at least they may be adopted as a model for the synthesis of new antifungal agents.
S. Eshghi, E. Tafazoli,
Volume 10, Issue 4 (1-2007)
Abstract
Today, the production of disease-free and identical rootstock seedling in protected environments is a common practice in citrus industry. The process is time consuming, laborious and expensive. Shortening the period to reach suitable size for budding results in the reduction of the costs. It is possible to shorten the period for budding in citrus seedlings through the application of growth regulators. As lime is used widely as a rootstock in Southern Iran, this research attempted to study the effect of paclobutrozol (PP333), ethephon and pinching following gibberellic acid (GA3) treatment on height, diameter and budtake of lime seedlings. To do the research, seedlings with 4-6 leaves were sprayed with 100 mg/L GA3. After GA3 treatment, uniform seedlings 50 cm height were selected, potted and sprayed with PP333 (500 and 1000 mg/L), ethephon (150 and 300 mg/L) or pinched. All treatments, compared with control, increased height, diameter and fresh weight of shoot significantly. GA3 alone caused internode elongation. The effect of all treatments on the number of node, fresh and dry weights of root was not significant. Ethephon reduced chlorophyll content of leaf. And ethephon (300 mg/L) and PP333 (1000 mg/L) reduced budtake percentage of lime seedlings.
Z. Adavi, M. Mobli, K. Razmjoo, E. Landi,
Volume 10, Issue 4 (1-2007)
Abstract
In order to study the effects of salinity of irrigation water on the growth and quality of 10 bermudagrass cultivars under saline soil, a factorial plot experiment using a complete randomized block design with three replications was carried out at College of Agriculture, Isfahan University of Technology in 2002-2003. Ten cultivars under five levels of irrigation water salinity (3.30, 6.93, 10.2, 14.8, 17.8 dsm-1) were studied. During experiment, visual appearance of color (1 to 9, best 9), and leaf area, shoot and root dry weights and length and number of stolones were measured. Results showed that salinity of irrigation water affected color of different cultivars, such that with increase in the level of salinity, color decreased. Cultivars showed better color in August, but lower color in January. Annual mean indexes showed that ISF2 and Tifdwarf had highest and lowest color, respectively. Also, with increase in salinity levels, leaf area, foliage dry weight, length and number of stolones reduced. With increase in salinity of irrigation water from 3.30 to 10.2 dsm-1 root dry weight increased, but reduced in higher salinity levels. Due to significant interaction effects between salinity and cultivars for most traits, the responses of cultivars were different. Large differences observed between cultivars for most of traits indicated high genetic variation among the studied bermudagrass cultivars. Under high level of salinity conditions, JP2 and Tifway for foliage dry weight, 3200W18-4 and ISF2 for root dry weight, and cultivars Midlawn and 3200W18-4 for leaf area, were recognized as more tolerant than others.
S. Sharif, M. Saffari, Y. Emam,
Volume 10, Issue 4 (1-2007)
Abstract
Many experiments have been carried out to alleviate the negative effect of drought stress and to obtain suitable growth under water deficient condition. Application of plant growth regulators (especially growth retardants) is one of the proposed methods. In a greenhouse experiment using a completely randomized block design with 4 replications at Kerman University Agricultural Department, the effect of 4 drought levels 25, 45, 65, 85 percent of field capacity and 3 different concentrations of chlormequat chloride 0, 1500, and 3000 mg/liter on some factors of winter barley cultivar Valfajr was investigated. Results indicated that increasing the cycocel concentration from 0 to 3000 milligram per liter leads to significant decrease in plant height. Relative water content affected by growth retardants was increased. Numbers of tillers and root and shoot dry weight, were also decreased because of applying cycocel in dry condition. The result also indicated that the root/shoot dry weight ratio, grain number per ear and ear number in dry condition without stress would increase using cycocel treatment.
A. R. Valdiani, M. Tajbakhsh,
Volume 11, Issue 1 (4-2007)
Abstract
A total of 25 advanced rapeseed (Brassica napus L.) varieties were evaluated under cold weather conditions using Randomized Complete Block design (RCBD) with four replications in Dr. Nakhjavani Agricultural Research Station, 35 km North-East of Urmia the capital of West Azerbaijan province in 2000-2001. The results showed significant differences among the varieties (P ≥ 0.01) for all the phenological stages including days to germination, days to rosette completion, days to initiation of stem elongation, days to flowering initiation, pod formation stage and days to maturity. The spring varieties Sarigol (PF7045/91), Hyola 42 and SYN1 and autumnal varieties Alice, Eurol, Fornax, VDH 8003-98, Consul, Licord and Zarfam (Regent× Cobra), showed early maturity. On the other hand, Mohican, Olara, Colvert, L-1 and Akamar were late mature varieties. In fact, the most prolific varieties, DP.94.8, Zarfam (Regent ×Cobra) Cocktail, Consul and SLM046 (control variety) had the highest ability survive in the cold conditions and they completed their rosette stage sooner than the other varieties. There was positive and significant correlation between duration of pod formation stage and seed yield. Maturity date of varieties was positively and significantly correlated with harvest index, number of seed per pod, days to germination, days to rosette completion, days to stem elongation, days to flowering, and days to pod formation. Negative and significant correlations were found between days to maturity and duration of flowering and pod formation stages. It can be concluded that delay in initiation or completion of each growth stages could delay maturity of the rapeseed varieties.
M. Shamsaddin Saied, H. Farahbakhsh, A. A Maghsoodi Mude,
Volume 11, Issue 41 (10-2007)
Abstract
In order to study the effects of salinity on germination, vegetative growth and some physiological characteristics of canola cultivars, two experiments were conducted at Research Station of Agricultural College of University of Kerman in 2004. The experimental design was a Completely Randomized Block with four replications. Treatments comprised all combinations of different levels of three factors including variety (Kobra × Regent, Ceres and Okapi), salt type (NaCl, CaCl2) and electrical conductivity of saline solution (0, 4, 8, 12 dS/m). Results of variance analysis showed that salinity has a very significant effect on germination percentage, germination homogeneity, germination rate, rootlet and polomul length at the end of the germination stage. Shoot length, dry weight, diameter and number of nodes per shoot were significantly affected also by salinity at vegetative growth. Regarding the two types of salt, none of the measured traits were significantly different. All the mentioned traits decreased with increasing salinity the highest and the lowest values were recorded at control and at 12 dS/m salinity levels. Membrane ion leakage was the only trait which increased significantly. Comparison of means showed germination percentage and germination homogeneity at germination stage and the number of nodes at vegetative growth stage were affected less than other traits by salinity, and they only decreased significantly with increasing salinity to 12dS/m. The effect of cultivar on these traits was also significant (P<0.001). In both growth stages, cultivars response to salinity was different. At germination stage, Ceres and Kobra * Regent cultivars were the most sensitive and tolerant ones in terms of all traits and there was no significant difference between Okapi and Kobra *Regent. At vegetative growth stage, however, Okapi showed less growth than Kobra * Regent and their difference was significant. It seems that evaluation of traits response at germination stage can not be effective to determine salt tolerance of canola cultivars.
S. Rajaee, H. A. Alikhani, F. Raiesi,
Volume 11, Issue 41 (10-2007)
Abstract
Azotobacter chroococcum is an important PGPR (Plant Growth Promoting Rhizobacteria) producing compounds needed for plant growth. The aim of this research was to study the effects of different native strains of Azotobacter chroococcum on growth and yield of wheat under greenhouse counditions. Seeds of spring wheat (Triticum aestivum L. var. Pishtaz) were inoculated with some Azotobacter chroococcum strains capable of producing IAA, HCN, sidrophore and fixing molecular nitrogen. The inoculation of wheat with those strains had a positive, significant effect on biological yield, seed protein percentage, thousand seed weight, leaf area, N, P, Fe and Zn uptake, in particular, by wheat. The increased growth of wheat was most likely due to the production of IAA and enhanced nitrogen fixation by inoculated strains. Some strains of Azotobacter chroococcum native to Chaharmahal va Bakhtiari are established as PGPR. Results also support the efficiency of Azotobacter chroococcum as an important biofertilizer in wheat cropping systems. The selected strains had a significant effect on wheat growth and yield, including biological yield and seed quality under greenhouse counditions. This beneficial effect of Azotobacter chroococcum on wheat is attributed mainly to IAA production and, to some extent to non symbiotic nitrogen fixation in the rhizosphere. So, these strains can potentially be used to improve wheat nutrition of micronutrients such as Fe and Zn, in particular.
H. Pourhadian , M.r. Khajehpour,
Volume 11, Issue 42 (1-2008)
Abstract
Planting patterns through growth indices affect yield formation. To evaluate these effects on safflower, Koseh local variety of Isfahan, a field experiment was conducted in summer, 2004 at the Agricultural Research Station, Isfahan University of Technology. The experiment was performed using a randomized complete block design with a split plot layout and four replications. Main plots consisted of three row distances (20 and 30 cm flat and 45 cm on bed), and sub-plots included two planting densities (40 and 50 plant m-2). The experiment was planted on June 25. The results showed that p lant canopy closed sooner, leaf area duration (LAD) increased and plant dry matter weight, leaf area index (LAI) and crop growth rate (CGR) were higher up to the middle of seed development as row distance decreased. In addition, the highest relative growth rate (RGR) and net assimilation rate (NAR) were obtained in 20 cm row distance. The highest (3039 kg ha-1) and lowest (1930 kg ha-1) seed yields were obtained with 20 and 40 cm row distances, respectively. Plant density did not affect the rate of canopy closure, CGR, RGR, NAR and seed yield. But, maximum plant dry weight, higher LAI and lower LAD values were obtained with 50 plants m-2. The results obtained in this experiment indicate that 20 cm row distance with 50 plants m-2 might be appropriate for summer planting of safflower, a local variety of Isfahan, under similar conditions.
A. Moalemi Ore , S.h. Karparvarfard,
Volume 11, Issue 42 (1-2008)
Abstract
This study was undertaken to investigate the effects of soil compaction due to wheel traffic on corn growth and yield, in summer 2004 and 2005 at the Badjgah Research Station, Shiraz University located in North West of Shiraz, Iran. The treatments consisted of axial load in two levels and wheel traffic location treatments at four levels, including none, between rows, on rows and on entire plot area. The corn growth rate, root density and yield were not significantly influenced by axial load, but they were significantly affected by wheel traffic in all plots. Corn yield with wheel traffic on entire plot area averaged 3.97 Mg/ha which was significantly lower than the yields with the other treatments which averaged 6.65 Mg/ha with no traffic.
H. Jalilvand,
Volume 11, Issue 42 (1-2008)
Abstract
This study was down in Forest Park of Noor. In order to determination of tree ring response to climatic variations, 35 cores were taken from dominant natural stand of common ash (Fraxinus excelsior L.). The guide of this study was finding which climatic variables are effective in the ring width growth of ash in current growing year and previous years (one, two and three years before current growing year) by multiple regression models at the North of IR-Iran. Totally, 85 annually, monthly seasons and seasonal growth climatic variations of precipitation, temperature, heat index, evapotranspiration and water balance were analyzed. The best multiple regression models were explained 83 percent of total variance of the growth of common ash. The results show that the growth of common ash was related to the previous year's climatic variations than that of the current year. The most effective role of climatic variations was due to the first and second preceding years (55%). Evapotranspiration of July and September, and precipitation of May in the second and precipitation of March in the third previous years, all were positively affected the growth of this species. This study revealed that ash is interested in warmer condition on early and middle of seasonal growth in present of available humid, and precipitation in the months of early growing season (Ordibehesht-Khordad of two previous years).
E. Zare, A.h. Chizari, Gh.r Pykani,
Volume 12, Issue 43 (4-2008)
Abstract
Malmquist index computed by data envelopment analysis approach was used to estimate the total factor productivity (TFP) growth in cotton production in Iran during 1983-2001. By dividing this index in the two components, technological change and technical efficiency change, two major factors of productivity growth in cotton production were analyzed. Data was obtained from production cost system and other statistical sources provided by ministry of Jahad-e-Agriculture. Results indicated that TFP growth in cotton crop was positive (0.8% per annum) for the period of this study .This figure was different in different provinces of Iran. Maximum growth rate was 6.2% in Fars province and was negative in Kerman, Mazanderan and Golestan provinces. In comparison, technical efficiency growth was more than technological change during 1983-2001.
