IRANIAN JOURNAL OF AGRICULTURAL SCIENCES (JOURNAL OF AGRICULTURE)
Year:2006 | Volume:37 | Issue:3|Papers Count:24

Two experiments in two different seasons were conducted to study the effects of nitrogen form of nutrient solution on two greenhouse cucumber cultivars. Five nutrient solutions with different ratios of NH4/NH4+N03, two cucumber cultivars (Soltan, Pardis), three replications and three plants in each plot were used in a split plot design. At the end of each experiment the characteristics of fruit yield, leaf and fruit dry matter percentage, and amount of nitrogen, phosphorus, potassium, calcium and magnesium in leaves were measured. Compound analysis of the two experiments revealed that: Fruit yield gradually decreased when NH4-N (in nutrient solution) increased. Maximum fruit yield was obtained in plants nourished with non NH4-N containing solution (approximately 5.6 kg), and minimum from plants nourished with high NH4-N containing solution (4.2 kg) Leaf and fruit dry matter decreased for nutrient solutions with a high concentration of NH4-N. Total nitrogen and phosphorus in leaves increased, while potassium, calcium and magnesium decreased with increasing ammonium concentration in solutions, which indicates antagonistic effect of elements. Yield in Pardis cultivar was more than in Soltan with other characteristics being also different between the two cultivars. It was concluded that cucumber cultivars preferN03-N to NH4-N.

Genetic diversity in sweet cherry (Prunus avium L.) was studied using molecular markers on a local (Iranian) and one imported cultivars. Several buffers, were initially employed and tested to select for the most suitable extraction buffer for seed, leaf stem bark, pollen, pistils and flower buds of Siah Mashhad variety. Results indicated that agents such as Polyvinyl-Polypyrolidone (PVPP) were not able to prevent phenolic comound activity and thus no protein bands appeared on polyacrylamid gel. Moreover different plant tissues, displayed different protein and phenolic activities. As a whole, stem bark followed by pollen and leaf, gave better protein activity response to the electrophoresis. Moreover, since bark was available at different times of the year, it was chosen as proper for genetic studies. Both statistical analysis, using Dice procedure, and comparison of the results with morphological characters, indicated that Mashhad, and Siah Mashhad, are genetically different cultivars despite their similarity in name and in fruit color.

This study was conducted to determine lysine requirement in laying hens, using plasma free lysine levels as a response criterion. The basal diet used was based on corn- corn gluten meal soybean meal, and contained 0.58% lysine, Nine graded levels of lysine (0.04, 0.08, 0.12, 0.16, 0.2,0.24,0.28,0.32,0.36%) were added to the basal diet. Each experimental diet was fed to 48 laying hens in a randomized complete design with 4 replicates in each treatment. Broken-line method was employed for estimation of lysine requirement. Dietary lysine levels exerted a significant effect on egg weight, egg mass output, feed intake (P<0.01), and feed conversation ratio (P<0.05), but did not significantly affect egg production. Based on egg mass output, feed conversion ratio and plasma free lysine responses, lysine requirements were estimated at 675, 790 and 785 mg per hen -day; respectively. The results suggest that plasma free lysine could be a precise indicator (R2=0.96) for determining lysine requirement in laying hens. In conclusion, based on the results of this experiment, daily lysine requirement of laying hens during peak egg production was estimated at 785-790 mg per hen-day.

Biological control of root knot nematode (Meloidogyne javanica) through Trichoderma viride was investigated in greenhouse conditions. In comparison with the control, different concentrations of the spore of fungus (as treatments) decreased the disease level, egg mass production per plant and mean number of eggs per egg mass (P<0.05). Different concentrations of spore of antagonist decreased the disease level (gall numbers), but in concentration of less than 104 spore/ml there were no significant differences observed among treatments in egg mass production per plant, and at the concentrations of 104-107 spore/ml of the antagonist there were significant differences observed among treatments. There were significant differences among treatments (Trichoderma+ nematode) in egg number per egg mass only at 102 spore/ml of antagonist. Trichoderma viride decreased disease level (gall size means) and mean number of egg mass per plant even after plant inoculation by the nematode. There were significant differences in number of egg mass production per plant and the number of eggs per egg mass at giant cells production stage (4 days after nematode penetration in to the roots), but at the formation of the young adult stage of nematode (15 days after nematode penetration into the roots), only the number of egg mass production per plant was decreased. Maximum level of egg hatching (in control) was observed to be three days after incubation, while in treatments (Trichoderma+ nematode) it was six days after incubation.

The sweetpotato whitefly, Bemisia tabaci (Genn.) and silverleaf whitefly B. argentifolii Bellows and Perring (Horn.: Aleyrodidae) are major pests of field crops, vegetables and ornamentals in Iran. Economic losses from this pest may either be caused through viral transmission, the excretion of honeydew or by direct damage to the plants. RAPD technique was employed to detect genetic diversity and dispersal of 11 Bemisia tabaci populations during 2002. The infested leaves bearing nymphs and pupae were collected from Darab, Qom, Saveh, Gonbad, Gorgan, Varamin, Garmsar, Orzoiieh (Kerman), Rafsanjan, Shooshtar, and College of Agriculture (T.M.U.) cotton fields. Nymphs and pupae were cultured in a growth chamber under 24±2°C, 55±3% RH and 16:8 (L: D) photoperiod conditions. Five decamer primers were used in amplification reactions. All primers produced polymorphic bands. In general 71 RAPD markers were detected. Amplified DNA fragments ranged in size from 200 to 3000 bp. The results revealed that except for Rafsanjan, all other populations consisted of B. tabaci and B. argentifolii. The results indicated that RAPD marker is useful to the study of DNA polymorphism in B. tabaci.

Cymbopogon is an aromatic plant that belongs to Poaceae family. Various essential oil constituents in its different species are extensively used in cosmetics, perfumery and pharmaceutical preparations. Also, some of their components are of considerable biological activity. In this study, aerial parts of C. parkeri were collected from its natural habitat (Dehbakri (Jiroft» and also from plants that have been introduced from this habitat into Zardband medicinal plant botanic garden in north Tehran. After extraction of essential oils, identification of their components was done through GC-MS. The antifungal activity of the essential oil of wild plants was evaluated in vitro against three phytopathogenic fungi: Pyricularia oryzae, Rhizoctonia solani and Fusarium oxysporum. Results indicated that oil yield in wild plants was 2.46% while it was 0.95% (w/w) in introduced to Zardband plants. Through oil analysis eleven components were identified that represented more than 99% of the oil. Among identified compounds, in both wild and cultivated samples Piperitone (82/96% and 87/59% respectively) was the major component. Bioassay studies indicated that the essential oil benefits from strong fungistate activity, so that concentrations of 600 ppm of the oil inhibited growth of all tested fungi completely.

The aim of this study was to compare wool growth and quality in twin- and tripletbearing/rearing ewes, offered different sward heights. After pregnancy scanning, 94 Romney ewes of six week wool growth were randomly allocated to four different sward heights (2, 4, 6 and 8 cm). Within the first 24 hours of parturition ewes were transferred to one of two sward heights (4 and 8 cm). In ewes shorn 87 days after parturition, the fleece was weighed and a sample taken from midside for evaluation of fleece characteristics. Fleeces from twin bearing/ rearing ewes tended to be heavier (P<0.1; 2.0 Kg vs 1.9 Kg) than those from triplet bearing/ rearing ewes. Other wool characteristics were not affected by litter size. Ewes offered 2 cm long sward during the last half of pregnancy bore lighter (1.6 vs 2.2 Kg, P<0.05) and finer (39.0 vs 41.8 mm, P<0.05) fleeces than those offered 4 cm, but there was no increase in weight or fineness for those offered sward more than 4 cm height. Post parturition nutritional treatments had no significant effects on wool characteristics. In terms of wool growth and wool processing characteristics, it seems being of little benefit to offer twin or triplet bearing ewes a sward higher than 4 cm. There were no interactions observed between nutritional treatment and litter size for any wool characteristic measurements.

Powdery mildew of wheat caused by Blumeria graminis f. sp. tritici is one of the important diseases prevalent in Mazandaran and Golestan provinces in Iran. To control powdery mildew through use of resistance cultivars, it is necessary to determine the virulence level of the isolates. Isolates of B. graminis f. sp. tritici were collected from different fields in the two provinces in 2004. Virulence/avirulence genes of the isolates were verified through differential cultivars carrying resistance genes to wheat powdery mildew. Primary seedling leaves (10-12 day) of differential wheat cultivars were inoculated by single pustule isolates of B. graminis f. sp. trifici. Reaction of inoculated seedlings evaluated by 0-9 scale and virulence frequency of isolates were determined on resistance genes. Eight different pathotypes of wheat powdery mildew were identified through useof a system of designation of pathotypes of the plant pathogen. Pathotype 7.7.7.2.5 carrying virulence on 12 different Pm genes were found to be the most virulent pathotypes, while pathotypes 1.1.6.0.0 with virulence on only four Pm genes were the weakest ones. No virulence was observed on Pm2+4b+8 resistance genes while all isolates were virulent on Pm l gene. High frequencies of virulence to genes Pm l, Pm3a, Pm3b, Pm4a, Pm8, Pm3c, Pm5 and Pm6 were found in both locations (Provinces). Frequency levels of virulence for Pm2, Pm3d and Pm1+2+9 were intermediate, while frequencies for Pm7, Pm17, Pm2+6 and Pm2+4b+8 were low. It seems that B. graminis f. sp. tritici population in Mazandaran and Golestan provinces is composed of complex and highly varied pathotypes, and , this complexity and variation should be taken into account in strategies intended for deployment of resistant genes.

The effect of eight citrus rootstocks was studied on postharvest quality, including storability of two cultivars of grapefruit namely, Marsh and Ruby Red for five months in cold storage of 10o C with 85% RH for 12 year- old tree fruits. Fruits of trees grafted on Cleopatra mandarin, Carrize citrange, Troyer citrange, Swingle citromelo, Sour orange, Volkamera lemon, Amblycarpa, and King mandarin were tested at the Agricultural Research Station in Dezful. The effect of cultivars and rootstocks as well as the interaction between them was studied in the form of a factorial completely randomized design. Results indicated that varying citrus rootstocks had significant influence on storage life of grapefruit during storage. Regardless of rootstocks, cultivars had no effect on storage life and in most cases, differences were not statistically significant. After five months of storage at 10o C, percentage of fruit decay was high (ca. 5%) in fruit grafted on King mandarin rootstocks for both cultivars but least fruit decay was measured for fruits from Volkamera (0.85%). Percentage of weight loss in fruit after storage was high in fruit from Cleopatra mandarin (ca. 15%) and least in fruit grafted on Volkamera lemon (ca. 6%). At the end of storage period, reduction in other fruit qualities i.e. percentage of Juice, TSS, titrable acid (TA) and vitamin C content were almost minimum in fruit grafted on Volkamera, as compared to those grafted on other rootstocks.

Bacterial canker disease is prevalent in all stone fruit growing areas and mainly on cherry trees. As susceptibility of sweet cherry to the disease is dependent on tree species, using resistant cultivars will decrease the disease occurrence rate. In this study 21 sweet cherry cultivars grafted on Pronus mahaleb were tested for determination of their partial resistance to Pseudomonas syringae under greenhouse as well as field conditions. The bacterial agent was injected into cherry seedling and rate of disease progress measured. Results indicated significant differences among the tested cherry cultivars. Cherry cultivars Shoaosaltaneh, SiaheMashhad, Blamarkad, Shabestar, Hajuosefi, Napelon, DirraseItalia, RoodChoon and Gazvin exhibited more resistance. Cherry cultivars Hybrid 1 Karadj, SiaheDaneshkadeh, Hamedan, Lambert, GhermezeRezaieh, Mashhad, ZardeDaneshkadeh, Arak, Abrdeh, and Mikers were categorized as semi-resistant. BloddyBarbon and GhermezeBagheno were categorized as susceptible. None of the tested sweet cherry cultivars showed complete resistance to bacterial canker disease.

Seven aphid species were collected from almond trees in Najafabad and identified. Sexual females (oviparae) of Rhopalosiphum padi (L.) were collected from almond trees in fall, being the first report. Pterochloroides persicae, Brachycaudus amygdalinus (Schout.) and Hyalopterus amygdali (Blal1ch.) were the most common species and their injuries the most pronounced, hence they were considered as dominant species. Seasonal population fluctuation of P. persicae on almond was studied, including times of egg hatch, spring and fall outbreak, appearance and dispersal of winged forms, summer activity, oviposition, and number of eggs, overwintering situation as well as other host plants. The results indicated that brown peach aphid eggs hatched and nymph colonies were produced on 20-22 Feb. In late April alate forms appeared. Aestivating aphids were seen in orchards with. Humid conditions Fall colonies appeared in late Sep. with their numbers and populations increasing rapidly In mid Nov. oviparae appeared with each oviparous female producing 9.2±1.5 eggs.

Potassium is a very important nutrient in sugarcane nutrition, as well as in its quantity and quality of yield. For an evaluation of soil potassium availability and fertilization management, Quantity-Intensity (Q/I) curves are useful. This study was conducted to obtain such Q/I parameters as readily exchangeable potassium (DK0), slowly exchangeable potassium (Kx), potassium activity ratio (ARK)and potassium potential buffering capacity (PBCK)as well as correlations between these parameters and physical& chemical charactristics in 0-30 cm samples of soil under sugarcane cultivation in Khuzestan Province of Iran. The results indicated that DK0 ranged from 0.0353 to 0.2257 with an average of 0.0835 meq 100g-1, Kx from 1.063 to 4.143 with an average of 2.325 me 100g-1, AR0 ranging from 0.0125 to 0.0941 with an average of 0.040 (mmol L-1) 05, and finally PBCK ranging from 1.2034 to 3.0651 with an average of 2.232 (mmoil -1)05/( meq 100g-1). The Q/I curves followed the common shapes observed in literature but varied in different soils. Correlations between PBCK and clay percentage (r=0.83**), CEC (r=0.81**), and exchangeable potassium (r=0.62*) were significant but between cultivation history, and soluble potassium, and pH were not significant. The results also indicated that long-term cultivation caused the available potassium to decrease but it had no effect on unavailable potassium.

This study was conducted to evaluate four dietary L-carnitine inclusion levels on the performance and carcass characteristics of broiler chickens. Three hundred and twenty (day old) broiler chickens were received from a commercial hatchery and reared under optimum growth conditions until 42 days of age. Upon arrival, the chicks were randomly distributed into 16 floor pens in a complete random design (4 pens/trt, 20 birds/pen). L-carnitine levels were control, 200, 400 and 600 ppm. L-carnitine had no significant effect (P<0.05) either on feed intake or feed efficiency ratio, but had negligible influence on body weight gain and survivability, though this was not significant either. Various levels of L-carnitine exhibited no significant effect on carcass characterestic, abdominal fat and carcass parts (breast and leg). Morever, carcass chemical composition (protein, fat and carcass dry content) was not affected by L-carnitine levels.

Conidial and ascospore germination of Uncinula necatorn, the causal agent of grape powdery mildew, was studied at different temperatures and, in different relative humidities. The results indicated that ascospores germinated on dry microscopic slides (at saturation humidity in a rang) of 5-30oC. Maximum germanation of ascospores (37%) occurred at 25oC. Optimum germination was measured at a range of 20-30oC. Ascospore germination at 25oC on dry microscopic slides and at 100, 95, 76 and 54% relative humidities were found to be 37%, 4.5%, 0% and 0% , respectively. The conidia germinated over a wide range of temperatures and relative humidities on either of dry microscopic slides or grape leaves. Minimum temperature for conidial germination was 6°C with 21°C being optimum temperature for germination at saturation humidity. Conidia could germinate in between 54 to 100% r.h at a range of 5-35oC. On grape leaves, conidial germination occurred under 100 %r.h and at a range of 5-35 c. Maximum conidial germination on leaves took place at 15 and 25oC.

Species of subfamily Anthocorinae from alfalfa, potato and wheat fields in three different regions of the East Azerbaijan province were collected and identified during 2002-2004.Taxonomic characteristics of different parts of the body as well as male paramere were employed. Four species of Orius niger Wolff, O. minutus (Linnaeus), O. horvathi (Reuter) and Anthocoris pilosus (Jakovlev) were detected in alfalfa and potato fields that fed on thrips like Thrips tabaci, aphids such as Aphis craccivora Koch and Acyrthosiphon pisum Harris as well as mites such as Tetranychus urticae Koch. In wheat fields, only Orius niger was observed which feeded on thrips like Haplothrips tritici Kur. as well as aphids such as Schizaphis graminum Rondani and Sitobium avenae F An identification key to the species is presented. Among identified species, O. niger was dominant in alfalfa, potato and wheat fields in all the three different regions of the East Azerbaijan province. Also population density of O. niger in wheat fields along with four species of Anthocorinae in potato and alfalfa fields was higher at reproductive stages of the three crops than that at their vegetative stages, in the three studied regions.

An understanding of P sorption by soils is important for fertilizer recommendation. Little is known about P sorption characteristics of the calcareous soils of Hamadan province. In this study 15 soil samples of calcareous' soils were collected from Hamadan province. The objectives of the study were to evaluate P sorption by using adsorption isotherm models as well as the correlation of these equation parameters with soil properties. Phosphorus adsorption data were adequately described by Freundlich and the linear adsorption Isotherms, whereas Langmuir adsorption isotherm did not describe P adsorption in all soils. Phosphorus adsorption maxima (b) ranged from 69.93 to 204.08 mg kg-1. The constant related to binding energy (k) ranged from 0.1 to 2.0. Maximum buffering capacity (MBC) ranged from 12.9 to 238.08 mg kg-1. In Freundlich equation n parameter ranged from 0.26 to 0.99, and kd from 7.77 to 232.75 L kg-1. In the linear model, equilibrium buffering capacity (EBC) ranged from 4.88 to 126.61 L kg-1 and Labile P ranged from 0.71 to 29.37 mg kg-1. Standard phosphorus requirement, calculated by Langmuir, Freundlich and linear model, ranged from 3.21 to 34.01, 2.7 to 65.1, and 1.01 to 62.81 mg kg-1 respectively. The results indicated that adsorption isotherm parameters were significantly correlated with equivalent calcium carbonate, whereas not significantly correlated with other soil properties. The results of correlation studies among adsorption isotherm parameters revealed that K was significantly correlated with Freundlich equation parameters as well as Labile P, however b was not significantly correlated with Freundlich and linear model parameters. Parameter Kd was significantly correlated with EBC and Labile P, wherease n parameter was significantly correlated with Labile P. MBC was significantly correlated with EBC. The results finally indicated that Langmuir, Freundlich and linear models can be employed to describe P sorption characteristics, and calcium carbonate equivalent may affect P sorption  characteristics.

Because of high polymorphic information content (PIC) and other desirable properties, microsatellite markers are used as informative markers in genetic and breeding studies such as those of genetic diversity in crop plants. In this research, microsatellite markers were employed to evaluate genetic diversity and grouping of 72 grapevine cultivars, originated from Fars and Khorasan provinces as well as 18 European cultivars. Totally, 94 polymorphic alleles were found among 90 cultivars, with an average of 7.8 alleles and 4.4 effective alleles for 12 loci. Polymorphic information content values for these markers ranged from 0.417 (VVMD26) to 0.898 (VVMD5). The average expected and observed heterozygosity among 90 studied cultivars were 0.743 and 0.546, respectively. At all loci, except VVMD21, the expected heterozygosity values were higher than those observed. That could be due to the occurrence of null alleles at these loci. A comparison of allelic data among Europe, Fars, and Khorasan populations revealed similar levels of genetic variation in all groups. The mean number of alleles per population varied from 6 (Europe) to 6.41 (Khorasan). A comparision of population parameters indicated more similarity between Fars and Khorasan cultivars as compared with the European ones. Cluster analysis using UPGMA method based on Jaccard's coefficient of similarity divided cultivars into 8 groups. Results obtained from principal component analysis (PCA) also supported this grouping.

To identify the tylenchs associated with fruit trees, 140 soil samples were collected from the rhizosphere of several fruit trees in Jiroft area (Kerman province, Iran) in 2001-02. Nematodes were extracted from soil by sieving and through centrifugal sugar-flotation method. The specimens were killed, fixed by hot solution of formaldehyde, glycerin and acetic acid, (FGA; 4: 1: 1), processed to anhydrous glycerin by the modified Seinhorst method (De Grisse, 1969) and then examined by light microscopy. The following 34 tylenchid species belonging to 19 genera were identified: 1-Aphelenchoides asterocaudatus     18-Geocenamusbrevidens 2- Aphelenchoides bicaudatus           19-Geocenamusrugosus 3- Aphelenchoides limberi                 20-Helicotylenchusmulticinctus 4- Aphelenchoides spicomucronatus   21- Helicotylenchus pseudorobustus 5- Aphelenchoides subtenuis              22- Hemicriconemoides chitwoodi 6- Aphelenchus avenae                      23-Hirschmanneillagracilis 7- Basiria berylla                               24- Hoplolaimus indicus 8- Basiria tumida                               25- Hoplolaimus seinhorsti 9- Boleodorus thylactus                      26- lrantylenchus visinus 10-Criconemellaxenoplax                    27- Paratylenchus coronatus 11-Ditylenchus myceliophagus             28- Pratylenchus neglectus 12-Filenchus andrassy                        29- Pratylenchus Thornei 13-Filenchus facultativus                     30-Psilenchus hilarulus 14-Filenchus misellus                          31-Psilenchus hilarus 15-Filenchuspolyhypnus                       32- Seinura demani 16-Filenchus vulgaris                           33- Tylenchorhynchus mashhoodi 17-Geocenamusalboranensis                34- Tylenchulus semipenetrans Four species, namely Hirschmanniella gracilis; Hoplolaimus seinhorsti; Paratylenchus coronatus and Hemicriconemoides chitwoodi were new to nematode fauna of Iran, while Filenchus polyhypnus being recorded for the secound time in the country. Their morphological and morphometrical characteristics are described.

Water shortage and low efficiency of water use in traditional agricultural systems are limiting factors in agriculture development in Iran. Therefore, an investigation of the effect of hydrophilic polymer and mulch on increasing water use efficiency is crucial. To determine the effect of application of different levels of hydrophilic polymer Tarawat A200 (0, 2 and 4 g/plant) as well as dark mulch on vegetative growth (shoot, and root fresh and dry weight)as well as yield in field cultivated cucumber, cultivar Superdaminus in autumn culture, an experiment was carried out with three replications for two years. Results indicated that early yield in treatment of 4 g/plant of hydrophilic polymer along with dark mulch was about four times than that in control (280 g/plant and 73 g/plant, respectively). Four g/plant of hydrophilic polymer led to 76% increase in total yield as compared with control. Total yield in the application of 4 g/palnt hydrophilic polymer treatment together with dark mulch was 115% control. It is therefore recommended to apply4 g/plant of hydrophilic polymer Tarawat A200 along with dark mulch in field grown cucumber, cultivar Superdaminus, in autumn culture, for better yields.

The effects of irrigation systems (sprinkler and furrow) on sap sucking pests (thrips, leafhopper, mite), black dot disease, as well as growth trend in potato cultivars (Agria, Marfona, Hertha, Cosmos and Picasso) were investigated. The experiment was carried out for 2 years and arranged in split plot design. Results on pests indicated that population densities of thrips, leafhopper, and mites in sprinkler irrigation treatment' were 12.5,60 and 100% lower than those in furrow irrigation respectively. Infection rate of black dot (in all potato cultivars) was higher in furrow system treatment, with the difference between furrow and the other system being significant at 1% level. Growth trend in potato cultivars indicated that sprinkler irrigation fresh weight of vegetative growth was more than that in furrow irrigation, but tuber weight, until 120 (DAP), in furrow irrigation was more than that in sprinkler irrigation. Analysis of combined data showed that, at the same harvest date, there was not any significant differences observed, in potato yields and secondary tuber growth, either among between cultivars or between the two irrigation system.