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ٍsayed Mohammad Hashemi, Javad Pourreza,
Volume 2, Issue 3 (10-1998)
Abstract

This experiment was carried out to study the effects of different levels of vitamin C (0, 150, 300 and 450 ppm) and cage density (3, 4 and 5 birds) on performance and egg shell quality of laying hens under high environmental temperature. In a completely randomized design with 3 × 4 factorial arrangement, one hundred and ninety two (192) 25 week white leghorn hens were divided into 48 replicates four hens per replicate. The experimental period lasted 90 days. The criteria measured were: percentage production, egg weight, egg output, feed conversion ratio, shell thickness, shell weight, shell calcium and albumin height. Daily egg production and biweekly egg weight, shell thickness, shell weight and albumin height were recorded. Shell c1acium was measured at the end of the experiment's period. The results indicate that, 150 ppm vitamin C significantly (P < 0.05) increased egg weight and shell calcium. Albumin height was significantly (P < 0.05) increased at 300 ppm vitamin C supplementation. Cage density had no effects on shell weight, thickness and calcium, and albumin height. Egg weight, egg production and egg output were reduced significantly (P < 0.05) due to increased cage density. Feed conversion ratio was also increased significantly (P < 0.05) as cage density was increased. Interactions between vitamin C and cage density on shell and egg weight were significant (P < 0.05).
Mansour Zibaei, Gholam Reza Soltani, Ahmad Ali Keykha,
Volume 2, Issue 4 (1-1999)
Abstract

The production and acreage of corn in Iran and in Fars Province, in particular, are expanding at an increasing rate. The impacts of this event was studied by a risk programming model (MOTAD). The results indicated that the optimal cropping patterns with corn had less variance than the optimal patterns without corn in all income levels. The results also showed that with the introduction of corn into cropping pattern, the use of land and water were increased, but the rate of increase in the use of land was more than the rate of increase in the use of water. By determining risk - aversion coefficient for the sample farmers, their sensitivity to corn price changes were studied. The results indicated that the relationship between corn and wheat is complementary but it is competing with barley, sugarbeet, cotton, cucurbits and legumes.
Mahmood Alichi, Ali Asghar Ahmadi,
Volume 3, Issue 1 (4-1999)
Abstract

The effectiveness of Buprofezin (40% SC) and Pyriproxifen (10% EC) on the mortality of nymphal stages and fecundity of cottony cushion scale was investigated under glasshouse conditions. The LC50 of IGRs was also determined for the first nymphal stage. Two applications were conducted at intervals of 1 day prior to introduction of crawlers and 42 days after infestation. The results indicated that Buprofezin was superior to Pyriproxifen in suppressing the growth and development of crawlers. The mortality of first instars was determined 28 days after the first application. Although the total mortality of second instars due to Pyriproxifen was higher than that by Buprofezin, but the cummulative mortality of 1000 ppm treatment was estimated to be 100% in both experiments after 42 days. The effect of Buprofezin on incomplete molting of nymphs and its ovicidal activity showed a decreasing rate in third instar nymphs survival and fecundity of cottony cushion scale in relation to different concentrations of the IGRs, but it never reached 100%. Meanwhile the 1000 ppm concentration of Pyriproxifen in the same treatments brought about complete mortality to third instar nymphs and inhibited adult and egg formation due to imbalanced juvenile hormone activity. However in 1 ppm concentration of Pyriproxifen, a noticeable increase in fecundity of cottony cushion scale was observed.
Sayed Ali Mohammad Mirmohammadi Maibody,
Volume 3, Issue 1 (4-1999)
Abstract

The reproductive development stage is a crucial stage in plant life to study the potential of plant yield. Salt tolerance in this stage is desirable to obtain a stable and high yield. A Cynodon dactylon population from America (Cyn3, London Univ. Collection), was suitable to study the detached immature inflorescence in booting stage on liquid medium. The detached inflorescenes were cultured on a liquid medium prepared with or without various supplements of NaCl (0 to 2%) and kinetin concentrations. The sequence of morphological events of spike development in vitro, and the effects of NaCl on spikelet opening, embryo sac growth, fertilization and caryopsis development were studied. The liquid medium supplemented with 10-7 M kinetin resulted in natural caryopsis development. Supplementing NaCl to the liquid medium had deteriorating effects on the embryo sac development and resulted in the production of abnormal caryopses. The abnormal caryopses were smaller in diameter with a more fragile pericarp. However, a small number of spikelets grown in liquid medium, supplemented with low salt concentration up to 5%, produced normal caryopses and germinated well on soaked filter paper in petri dishes at appropriate conditions.
Hassan Nassiri Moghaddam, Sayed Hamid Reza Razian, Fariborz Khajeh Ali,
Volume 3, Issue 1 (4-1999)
Abstract

Effect of different sources of fat on performance of broiler chicks was studied. Three hundred and thirty six chicks were divided into 42 groups of 8 chicks per group. Seven isoenergetic and isonitrogenous diets, mainly based on corn and soybean meal were prepared and fed. These treatments were as follows: corn + soybean meal + (5% tallow, 5% cotton seed crude oil, 5% cotton seed soapstock, 2.5% tallow + 2.5% crude oil, 2.5% tallow + 2.5% soapstock, or 2.5% crude oil + 2.5% soapstock). One control diet without any source of fat was also included. Results showed that average feed intake of diets with different sources of fat up to 56 days old, was not differed from control group. Different sources of fat and their combinations increased weight gain and improved feed conversion. But soapstock had no effect on performance. Added fats increased abdominal fat of chickens. Therefore, if is concluded that on the contrary to soapstock, tallow and crude oil enhanced performance of broiler chickens.
Mohammad Ali Edriss, Javad Pourreza, Saeid Ansari,
Volume 3, Issue 1 (4-1999)
Abstract

This experiment was conducted to study egg production traits in a flock of native fowl from Isfahan region and their crosses with three improved exotic breeds. Sexual maturity (SM), weight of the first egg (WFE), number of eggs (EP), egg weight (EW), feed intake (FI), and feed conversion ratio (FCR) were recorded individually during laying period up to 52 weeks of age. There were no significant differences (P < 0.05) in WFE between the four groups, but the difference between the four genetic groups was highly significant (P < 0.01) for SM, EP, EW, FI and FCR. During laying period, pooled coefficients of heritability (sire component) for SM, WFE, EP, EW, FI and FCR were estimated to be 0.24 ± 0.10, 0.03 ± 0.08, 0.41 ± 0.12, 0.48 ± 0.12, 0.13 ± 0.09 and 0.18 ± 0.09, respectively. In combined analysis, part record egg production (SM to 34 weeks of age) was positively correlated (genetically and phenotypically) with EP up to 52 weeks of age (rg = 0.74 ± 0.11, rp = 0.71). The values suggested that there is a relatively appropriate relationship in the combined groups analysis. In addition, EP up to 34 weeks of age was negatively correlated with FCR during the same period (rg = -0.92 ± 0.53, rp = -0.81).The estimated genetic and phenotypic correlation in this study suggested that selection based on part record egg production can not only be used successfully to improve EP during full record, but may also cause a better laying performance during laying period.
Heshmatollah Khosravinia, Mohammad Ali Edriss, Javad Pourreza, Saeid Ansari,
Volume 3, Issue 1 (4-1999)
Abstract

To estimate heritability, and genetic and phenotypic relationships and also to study the effect of sex and rearing environment on body weight, weight gain, feed consumption and feed conversion coefficient, the data from 1200 pedigreed male and female chickens from three genetic groups including 90 sires were used. The included genetic groups were crosses of native chickens and an exotic breed (group A), native chickens which were selected for two generations on the basis of 8th week body weight (group B) and a control group of native chickens (group C). All the chicks were reared up to four weeks of age on the ground in separated pens according to their sire groups. In order to calculate feed conversion coefficient, 498 chicks were placed in individual cages during four to ten weeks of age. The results showed that the cross group (A) compared to the other two groups had a higher body weight at 2, 3, 6, 8 and 10 weeks of age. Weight gain, feed conversion coefficient and consumption at periods of 4-6, 6-8, 8-10 and 4-10 weeks were also higher in the cross group. Genetic groups B and C, in spite of better performance of group B for most of the traits, did not have any significant differences for the compared traits. Estimated heritabilities on the basis of sire variance component showed that these traits were medium to highly heritable. Estimated heritabilities for feed consumption at different ages ranged from 0.15 to 0.44 which at any age was lower than that estimated for feed conversion coefficient. Genetic and phenotypic correlations between growth traits were positive and, in most of the cases, high. Correlations between nutritional traits at different ages were variable.
Reza Jamshidian, Mohammad Reza Khajehpour,
Volume 3, Issue 1 (4-1999)
Abstract

Limited time for crop residue decomposition and complete seedbed preparation in double-cropping necessitates reduced tillage which is associated with its shortcomings. Information about seedbed preparation aspects in double-cropping of wheat and mungbean in Isfahan is lacking. For this reason, the effects of various seedbed preparation methods on growth, seed yield and yield components of mungbean (experimental line 1-61-16) were studied in a wheat-mungbean double-cropping system during 1996 at the Agricultural Research Station, Isfahan University of Technology. Two residue management treatments (burned and nonburned) along with four tillage systems: moldboard plow, disk, khischee and no-till were laid out in a strip plot design within a randomized complete block design with four replications. Improved establishment and plant growth conditions associated with burning residue treatment significantly increased plant density, above ground plant weight, number of nodes per branch, plant height, number of pods per main stem and per square meter, number of seeds per pod on main stem and on branches, number of seeds per main stem, seed yield, biological yield and harvest index. Higher plant density in this treatment resulted in significant reduction in the number of branches and number of pods per branch. Desirable conditions for establishment and growth in disk and moldboard plow treatments significantly increased plant density, above ground plant weight, number of pods per main stem and per square meter, number of seeds per pod on main stem and on branches, number of seeds per main stem, seed yield, biological yield and harvest index. No-till treatment produced the least results in respect to the above traits. The results indicated that burning residues with disk tillage system might be an appropriate seedbed preparation method under conditions similar to this experiment.
Sayed Shahram Mirodjagh, Ahmad Arzani,
Volume 3, Issue 1 (4-1999)
Abstract

In vitro salt tolerance of 28 cultivars of durum wheat with native and exotic origins was investigated, using MS medium containing sodium chloride. The resulting calli were subjected to 8 salinity levels including 0, 0.3, 0.6, 0.9, 1.2, 1.5 and 1.8 percent NaCl (w/v). Donor plants of explant (immature embryo) were grown in a recirculating hydroponics and pots in a greenhouse as well as in the field. Assessment of calli was conducted after 0, 8 and 16 days after subculture of calli into the NaCl-contained medium. Callus growth rate, relative callus growth rate and percentages of callus necrosis were measured, using a 8 × 28 factorial experiment layout in a completely randomized design with 3 observations per treatment and 3 replications. Results of analysis of variances showed that among the criteria, relative growth rate of callus was the most reliable, while callus growth rate as not being quantitatively measured, was less devoted. Results of this study revealed that 'PI 40100' and 'Dipper-6' were superior genotypes for in vitro salt tolerance. The high relative callus growth rate and less callus necrosis of these cvs. may indicate their superior genetic potential for in vitro salinity tolerance.
Jahangard Mohammadi,
Volume 3, Issue 1 (4-1999)
Abstract

The analysis of the EC data set indicated that the spatial distribution of EC data of different depths are closely related to one another. It means that they are spatially cross correlated on one another and can be considered to be co-regionalized. It also implies that EC values at a particular depth contain useful information about the other depths which can be used to improve their estimation. In this research, we aimed to investigate the effects of using relevant ancillary information in the estimation procedure. To do this, cokriging was used. To evaluate this algorithm as a potential tool for mapping EC, its performance on the independent test data was evaluated and compared with the results obtained from studies using kriging. The results of the co-regionalization of EC at different depths indicated that cokriging the salinity data, although more rigorous from theoretical point of view, displayed no advantage over independent ordinary kriging at each depth. The results confirmed that cokriging improves little over ordinary kriging if the primary and auxiliary variables are almost equally sampled and all the variograms are identical. Also, ordinary kriging showed to be quite self-consistent since the predicted average salinity profile over the three depths was almost identical to the one predicted by cokriging. Considering the complexity of the cokriging and the LMC modeling, it is clear that there is no gain in using co-regionalization.
Ali Pishnamazi, Javad Pourreza,
Volume 3, Issue 2 (7-1999)
Abstract

Barley consumption is limited in broiler chicken diet due to their β. glucanas polysaccharide content. The application of synthetic enzymes in poultry diet can increase the barley content. The purpose of this experiment is to study the effect of enzyme supplement-β-glucanas on the performance of broiler chickens, percentage of abdominal fat, intestine weight and economic evaluation of production of one kilogram of meat in diets including different levels of barley and corn. Five hundred forty-one-day-old commercial broiler chickens (Arian) were divided into 45 groups, 12 chickens per group Each one of the 15 experimental diets, in which barley was substituted for corn at levels 0, 25, 50, 75 and 100% with 2 levels of enzymes (0.025 and 0.05%) was fed to 3 groups of chickens for 49 days. All diets were isoenergetic and isonitrogenous. Plant oil was used to make diets isoenergetic. The results showed that the rate of weight increase of broiler chickens decreased as each level of free enzyme barley was replaced at 0.83, 6.08, 12.9, 16.1 %, respectively. The weight gain of the chickens fed with diets including a large amount of barley and 0.05% enzyme didn’t have any significant difference (P < 0.01) with the control group. The chickens fed with diet including barley and 0.025% enzyme didn’t have any significant difference either (except at 75% and 100% barley replacements). Enzyme supplementary at 0.025% and 0.05% levels (especially at 0.05%) caused significant improvement (P < 0.01) in food consumption and feed conversion ratio of chickens fed with diets including barley. Analysing the carcass of these chickens showed that the enzyme used at both levels, especially at 0.05 %, caused a significant decrease (P < 0.01) in abdominal fat (3.62% vs. 4%). It was also seen that the weight of chickens fed with enzyme decreased significantly (P < 0.01) in comparison with chickens fed with free enzyme barley diets (9.57% vs. 14.81 %). The economic calculation results of producing meat in this experiment pointed out that using barley and corn caused reduction in production expenses. The general results of this study showed that barley with enzyme is a suitable replacement for enzyme and further that 0.05% level of enzyme is better than 0.025% level due to its performance and better economic results.
Mahmood Khoddambashi, Balram Sharma,
Volume 3, Issue 2 (7-1999)
Abstract

In spite of different reports about the inheritance of cotyledon colour in lentil, the precise nature of this phenomenon is unknown. In a comprehensive study, conducted in 1993-96 on inheritance of morphological markers in lentil, two types of green colour, light green and dark-green lentils, were distinguished for the first time. The dark-green showed monogenic and the light-green showed digenic inheritance. To explain this, involvement of three genes, Dg, Y and B in the inheritance of cotyledon colour were considered. At the dominant state of gene Dg, the genes Y and B produce yellow and brown pigments, respectively. At the recessive state (dg dg), no pigment will be produced and the dark-green colour will appear. If gene Dg acts normally (dominant state), but both genes Y and B are at recessive state (Dg-yybb), again no pigment will be produced and cotyledons will be of light-green colour.
Mohammad Shahedi, Payman Goli Khorasgani, Zohreh Hamidi Isfahani,
Volume 3, Issue 2 (7-1999)
Abstract

Stickiness and pastiness after cooking is one of the basic problems of macaroni production technology. Investigation of the factors affecting stickiness and pastiness of Iranian Macaroni is essential. The purpose of this research was to study the effects of percentage of gluten in the flour as well as extruder and drying temperatures on the macaroni quality. The factors studied are as follows:

1- Percentages of flour gluten at levels of 8.5, 10.5, 12.5 and 14.5 prepared by adding gluten to the macaroni flour purchased from the market.

2- Temperature of the dough discharged from the extruder (three levels: 48, 58 and 68 °C) obtained through changing the temperature of the water used in making the dough, circulation and noncirculation water in extruder jacket, and changing the rotational speed of extruder screw and increasing dough retention time.

3- Drying temperature (two levels: 50 and 62 °C) obtained through changing the number of burners in the heating system and using electrical heaters in the drying cabinet.

 The results of the e:xperiments and their evaluation are as follows: using flour with a gluten percentage of 12.5 or 14.5 (12.5% gluten is preferred for economic reasons) with an extruder temperature of 48 °C and a drying temperature of 62 °C will improve the macaroni quality. This treatment resulted in the production of macaroni with less stickiness, pastiness and cooking loss.


Farhad Ghavami, Abdolmajid Rezai, Siroos Abdemishani, Ahmad Arzani,
Volume 3, Issue 2 (7-1999)
Abstract

Variability of seed storage protein electrophoretic patterns revealed by SDS-Polyacrylamide gel electrophoresis and their possible relations with some morphological and phenological characteristics were studied using 193 accessions from Iran Mungbean (Vigna radiata L. Wilczek) Collection. Seed protein electrophoresis revealed six different patterns that were different in two albumin and four globulin subunits with molecular weights of 23500-34000. Pattern types 1 and 2 had a considerable frequency but pattern types 3, 4, 5 and 6 had low frequencies and probably had developed recently in mungbean evolution process. Cluster analysis of countries and cities using the frequencies of albumin and globulin subunits showed no relation between geographical diversity and similarity distances. The correlations of morphological traits and albumin and globulin subunits indicated a relationship between G1 and G2 subunits with 1000 seed weight and days to beginning of maturity. Therefore, selection based on protein patterns at preliminary stages of breeding programs might be effective in increasing seed yield together with earliness.
Sayed Farhad Mousavi, Jafar Jamshidnezhad-Anbarany, Sayed Saeid Eslamian, Nasser Rostam-Afshar,
Volume 3, Issue 2 (7-1999)
Abstract

Estimation of flood flow rate represents a method of preventing damages associated with this natural phenomenon. This estimation is one basis in the design of various hydraulic structures, dam spillways, watershed management and flood control. The maximum flow rate of floods is determined by methods such as Creager, Jarvis-Meyer, Cypress-Creek, and rational method. Rational-probability method is an alternative to estimate peak flood rates, and is expressed as:

 Q(y) = F. C(y). I(tc.y).A

 where Q is maximum flood flow rate (m3/sec) y is the return period (year) C(y) is runoff coefficient with a return period of y A is watershed area (km2) I is rainfall intensity (mm/hr) for a specified return period equal to time of concentration of the watershed and F is the conversion factor equal to 0.278 when the above units are used. The basic concept of this method is the same as that in the rational method except that the return period is also included in the equation. Usually, runoff coefficient, C(y), is determined empirically from tables cited in the literature (e.g., Chow et al., 1988). In the present research, data from 18 hydrometry and 6 rainfall-recording stations (located in Caspian - Sea watershed) were analysed using TR software. The Caspian - Sea watershed (which covers eastern and centeral parts of Iran's No. 1 main watershed) has the sub-basins of Atrak, Tadjan, Chalus, Sardabrood, Siahrood, Gorganrood, Safarood, Kesilian, Babolrood and Neka. Runoff coefficients with return periods of 2, 5, 10, 25, 50 and 100 years were determined for these sub-basins and iso-coefficient curves were plotted. The results showed that computed runoff coefficients were less than the values given in the literature because they are determined from observed flow rate and rainfall intensity in each catchment. It was also shown that runoff coefficient increased with increasing return periods. Application of the computed runoff coefficients in three sub-basins of the area resulted in more accurate estimations of maximum flood rate than when the values for these coefficients cited in the literature were applied.


N. Tomanian, A. Jalalian, A. Zolanvar,
Volume 3, Issue 3 (10-1999)
Abstract

Gypsiferous soils, as the most characteristic soil in arid and semi-arid regions, are widespread in Isfahan Province. The north-west region of Isfahan is a closed basin and is surrounded by geologic formations. This area is a part of Zayandehrood watershed. The origin of gypsum in this area was investigated in this study. Considering the geologic distribution of gypsum, twenty-two locations, suspected to have been affected by gypsum, were selected for sampling. Natural and artificial excavations were used to discover their relationships. To distinguish the differences between fresh and weathered shales, some fresh samples were taken from the depth of Shemshak formations (a lead mine).

Field observations showed that in Shemshak and Nayband formations, gypsic crystals were present within the layers of weathered shales, and pyrite was observed only in the mine shales. In weathered red conglomerates (Lower Cretaceous), considerable amounts of gypsum had accumulated. In the hydrothermal veins of Shemshak and Nayband formations, gypsic crystals were found in matrix or between rock layers. In some parts, the Qom formation (Evaporate sediments) contained plenty of gypsum.

From field observations and analytical data, such as mineralogy of untreated and floated rock powders, determination of residual sulfides in shales, and the examination of thin and polished sections of rocks, we conclude that the origin and main resources of gypsum in our study area are as follows:

1. Gypsum being released from Cretaceous limes particularly from red conglomerates

2. Oxidation of pyrite and any sulfidic minerals existing in shales

3. Gypsum being released from evaporates (Qom formation and Oligomiocenic Marls)

4. Gypsum formed through hydrothermal reactions during late Tertiary.


R. Amiri, A. Rezai, M. Shahedi, S. Dokhani,
Volume 3, Issue 3 (10-1999)
Abstract

This study was conducted to evaluate the capability of reversed-phase high performance liquid chromatography (RP-HPLC) of wheat (Triticum aestivum L.) storage proteins, and their genetic variability in different winter and spring isolines, cultivars and landraces. Gliadin proteins were extracted from the flour of five randomly selected seeds of each genotype. In this method, Nucleosil C18 300 A column (250×4.6 mm ID), equipped with a guard column and acetonitrile containing TFA as mobile phase was used.

All selected conditions for RP-HPLC such as suitable velocity and resolution were sufficient to achieve the objectives of this study. Under these conditions, the number of gliadin components by RP-HPLC analysis was more than electrophoresis subunits. In addition, quantitative results of RP-HPLC facilitated the data analysis. Also gliadin analysis by RP-HPLC had a high potential in detecting rye (Secale cereale L.) genes, so that the presence of ω-secalins in the genome of Falat variety was easily detected. Therefore, it was concluded that RP-HPLC analysis of gliadin proteins is as efficient as electrophoresis, and could even replace it in some cases. The result of cluster analysis for gliadin polypeptides indicated the gradual increase of genetic variation from isolines to landraces. Generally speaking, among the landraces, Ali Abad, Aghda, Sefid Bafghi, Ghermez Bafghi, Shahdas and Sorkheh had greater genetic variations.


B. Bahraini-Nejad, M.r. Khajehpour,
Volume 3, Issue 3 (10-1999)
Abstract

Combining herbicides for controlling broadleaf weeds and grasses in wheat farms has not been studied under Isfahan environmental conditions. Thus, this experiment was conducted in 1995-96 at the Agricultural Research Station, Isfahan University of Technology, in order to investigate the issue. In this study, 2,4-D+MCPA (U46 Combi Fluid 6), bromoxynil, metribuzin, diclofop-methyl and tralkoxydim and their combinations in 11 treatments plus weed-free and weedy checks were evaluated using a randomized complete block design with 4 replications. Goldbachia laevigata and Avena fatua were the dominant weeds. Cirsium arvense and Convolvulus arvensis were of less importance. Efficacy of bromoxynil on annual broadleaf weeds was higher than 2,4-D+MCPA, while 2,4-D+MCPA was more effective on perennial broadleaf weeds. Diclofop-methyl and combination of bromoxynil with tralkoxydim were the most effective on A. fatua, while differences between treatments containing diclofop-methyl or tralkoxydim on decreasing A. fatua numbers were non-significant. The most and the least visual damages to wheat plants were caused by metribuzin and bromoxynil, respectively. Wheat yield was not significantly affected by treatments. However, the highest yield was obtained by tralkoxydim + bromoxynil treatment, which produced the lowest total dry weight of weeds at terminal spikelet and heading stages of wheat. The results obtained here indicate that combination of bromoxynil with tralkoxydim might be the best treatment for the control of all annual weeds under conditions similar to this experiment. But if perennial broadleaf weeds and wild oat are dominant in the field, combination of 2,4-D+MCPAwith diclofop-methyl might be preferred.
G.h. Tahmasebi, D. Qujeq, R. Ebadi, M. Akhoundi,
Volume 3, Issue 4 (1-2000)
Abstract

An important and fundamental step in breeding honeybees is the separation of honeybee populations in Iran. During the years 1992-1996, several research works were directed towards the investigation of genetic populations of the Iranian honeybee (Apis mellifera L.), using biochemical methods. For this purpose, samples of worker bees were taken from 251 colonies of 115 apiaries in 84 cities in 21 provinces. The biochemical studies were conducted on thoracic proteins of worker bees using the horizontal electrophoresis.

The thoracic proteins of worker bees from the north and east populations isolated by electrophoretic techniques lacked a protein band having molecular weight of about 100,000 daltons. The results obtained from morphological and biochemical techniques and segregation of populations, indicate that breeding centers can be established in northern as well as western and central regions of Iran to improve genetic potentials of Iranian honeybee population. 


M. Kavossi, M. Kalbasi,
Volume 3, Issue 4 (1-2000)
Abstract

High-yielding rice varieties are prevailing in Guilan Province which is one of the most important rice producing regions in Iran. However, little is known about K status in this region and no suitable extraction method can yet be introduced to the farmers. This experiment was carried out to determine the available K by 15 chemical extractants and also to examine the critical K levels in paddy soils of the region. The treatments included 23 soils and 2 K levels (0 and 300 mg/kg as KCl) in a factorial experiment in a randomized complete block design with three replications.

 Results indicated that K application increased grain and straw yields, K concentration in straw as well as K uptake by rice. High correlation coefficients were observed between MgOAc, H2SO4, Morgan and 0.01 M CaCl2 methods with K concentration in straw (0, 0.83, 0.78, 0.8 and 0.78, respectively) and with K concentration in plant tops (0.79, 0.76, 0.75 and 0.73, respectively). Similarly, high correlation coefficients were observed between the same extraction methods with K absorbed by straw (0.83, 0.82, 0.78 and 0.76, respectively) and with total plant K uptake (0.79, 0.83, 0.74 and 0.71, respectively). Potassium critical levels by different extracting solutions were determined by Cate-Nelson procedure and were 38, 74, 160, 111, 36, 112 and 100 mg kg-1 for MgOAc, Morgan and Kelowana methods, Texas method H2SO4 0.01 M CaCl2 and NH4OAc without and with submergence of soil samples, respectively. In this study, available K was below the critical level in almost 75% of the soils.



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