AGROECOLOGY JOURNAL (JOURNAL OF NEW AGRICULTURAL SCIENCE)
Year:2010 | Volume:5 | Issue:17|Papers Count:13

Root rot is one of the most important disease of bean. Management of the disease is difficult because the pathogen is soil borne. In this study the effect of some strains of Rhizobium leguminosarum bacteria on Fusarium root rot of local Khomein chitti bean variety were evaluated in greenhouse condition. This experiment was conducted with 10 treatments (inoculation with 5 strains of Rhizobium, Rovral-TS fungicide, and healthy and infected control with water and suger-water) based on completely randomized design with four replications during 2007-2008. Results showed that  Rhizobium R-115 had the highest effect on disease severity reduction. This treatment reduced disease severity by 42% compared with infected control. There was no significant difference in disease severity reduction between the other Rhizobium tretments and Rovral-TS fungicide. R-115 increased N concentration (%1.59) compared with %0.74 in infected control. Also all Rhizobium treatments with increasing N concentration, improved plant growth with higher height, dry root and aerial plant weight.

Cotton bollworm, Helicoverpa armigera (Hübner) is a polyphagous pest which attacks a wide variety of agricultural crops. Habrobracon hebetor Say is one of the most important natural enemies of H. armigera in Iran. Adults of H. hebetor were obtained from insectary of Plant Protection Bureau of Bilehsavar in Ardabil Province and reared on Anagasta kuehniella larvae in laboratory. Rearing condition was 26±2oC, 70±5% RH, and photoperiod of 16: 8 hours (L: D). The effect of field recommended doses of Hexaflumuron, Profenofos, Spinosad and Thiodicarb were assessed on immature stages and the adult emergence of H. hebetor. Profenofos, Spinosad and Thiodicarb caused 73.62, 39, and 29.25 % reduction in adult emergence, respectively, and were classified as moderately harmful pesticides based on International Organization of Biological Control (IOBC) pesticide classification method. Hexaflumuron with 9.87 % reduction in adult emergence in spray method was classified as harmless.

Broom corn is cultured in broad areas as one of th most important agricultural crops in  Miyaneh region, Iran. Greenbug, Schizaphis graminum, an injurious cereal aphid, reduces the yield of the crop and so pestichdes Oxydemeton methyl and Thiometon were usually applicated 3-4 times to prevent aphid damage. In order to select effective pesticides for reducing application times, economic yield production and environmental safety, the effect of commen pesticides in broom corn fields (Oxydemeton methyl and Thiometon) was compared with Imidaclopride, Primicarb and Malathion on green bug. Results revealed that Imidaclopride, Primicarb and Oxydemeton methyl were the most effective pesticides on S. graminum. High Relative Potential Reduced Concentration (RPRC) of Imidaclopride, Primicarb and Oxydemeton methyl were duo to their low LC50 values on the aphid population, and indicated that their field recommended doses most probably can kill more than 50 percent of aphid population in the field condition. The highest Relative Potential Reduced Concentration value was observed in Imidaclopride with 22.56. Besides, Iranian formulations of Thiometon and Oxydemeton methyl were less effective than others and systemic pesticides were more effective than Malathion contact pesticid.

In order to investigate the effect of rotation and two nitrogen fertilizer rates on yield and some agronomic characteristics of Chamran wheat cultivar, an experiment was conducted as factorial based on randomized complete block design with four replications in experimental field of agriculture faculty of Ahvaz Shahid Chamran University in 2002. Rotation treatments including wheat-wheat, corn-wheat, sudangrass-wheat, mixed forage-wheat, suger beet-wheat and sudangrass-rape seed-wheat and nitrogen fertilizer requirement for producing 5 and 7 tons per hectare were considered as experimental factors. The results revealed significant effect of rotation and nitrogen levels on grain and stubble protein yield. The hieghest grain yield was obtained from sugeer beet-wheat and corn-wheat rotations in nitrogen level for 7 ton per hectare grain production .Nitrogen, phosphorus and potasium uptake amounts had no significant variation under rotation in all treatments. Nitrogen and phosphorus uptake amounts were lower than optimum and potasium uptake amount was optimum in Ahvaz climate condition.

In vitro formed plantlets perceive environmental stresses in transferring to in vivo condition due to their special morphological characteristics. Precise determination of differences between in vitro and acclimated plants can lead to successful acclimation of plantlets. Recently, optical studies are exploited as nondestructive and fast methods in exact determination of these differences. The current study was conducted to determine anatomical and morphological differences between ex vitro and in vivo plants by optical method. In this study, in vitro and acclimated plantlets of Boston fern, Nephrolepis exaltata Schott cv. Bostoniensis, which were cultured and rooted on 1/2 MS basal medium supplemented with 20 g.l-1 sucrose and 0.5 mg.l-1 benzyl adenine (BA) were used. Tri-dimensional pictures revealed that the surface of acclimated plant’s leaves were about 6-10 times smoother than in vitro ones. The comparison of reflective spectrum of in vitro and acclimated plantlets showed the most differences in the amplitude of the green wavelength (545-555 nm) and the red wavelength (670-685 nm).

An experiment was conducted to study relationships between grain yield with yield components, some physiological characters and determine the most effective characters on grain yield of 11 lentil varieties, one advanced line and one selected landrace genotype from Ardabil region local population, under dry farming conditions in Agricultural and Natural Resources Research Station of Ardabil. Treatments were arranged in a randomized complete block design with 3 replications. Results showed significant variation among studied genotypes for all measured characters. Ggenotypes ILL 8095, ILL 9893 and ILL 6031 produced higher grain yield. Path analysis of characters showed that pod numbers per plant and 100 grain weight were the most important effective components on grain yield with direct effect of 2.055 and 1.182, respectively. Positive direct effect of harvest index and biological yield on grain yield were nonsignificant. The highest positive indirect effects of these traits on yield occurred through number of full pods and 100 grain weight. Direct effects of total pod numbers per plant, lateral branch numbers per plant and the days to maturity on yield were negative. Results of this investigation indicated that characteristics of full pod numbers, 100 grain weight, harvest index, number of grains per pod, early flowering and relative water content of leaves can be introduced as selection indices for improving lentil grain yield in dry farming conditions.

This research was carried out for studying the effect of different plant densities and split application of nitrogen fertilizer on quantitative yield of Brussels sprout Ula De La Halle cultivar in Miyaneh region, Iran. Treatments were arranged as split plot based on randomized complete block design with three replications in 2008. Plant densities of 1.38, 1.58 and 1.82 plant/m² and split application of necessary nitrogen fertilizer including whole nitrogen fertilizer application in transplanting stage and splitting it, half in transplanting stage and the rest one month afterward, were considered as the main and  sub-plots, respectively. The results revealed that the interaction between plant density and nitrogen splitting was significant only in stem diameter trait. Plant density influenced plant height, stem diameter, leaf number, petiole length, petiole diameter, petiole weight, plant width, sprout number and sprout yield, significantly. Stem diameter, petiole diameter and plant width were decreased by increasing plant density. There was a positive correlation between the plant density and shrub height, leaf number, petiole length, petiole weight, sprout number and sprout yield. Nitrogen fertilizer splitting influenced plant height, stem diameter, petiole diameter and petiole weight, significantly. The application of the whole nitrogen fertilizer increased the plant height and stem diameter.

The exact identification of key pests and their host plants in a region has very important role for their successful control. Fauna of stem borers, Chilo Zincken, 1817 (Lepidoptera: Pyralidae) and their host plants were studied in Mazandaran province. Totally, four species including, C. partellus Swinhoe, C. phragmitellus Hubner, C. suppressalis Walker and C. sacchariphagus indicus (Kapur) were identified that among the mentioned species, C. sacchariphagus indicus is newly recorded for Iranian fauna. In a total of 17 host plants from 7 families including, Amarantaceae, Compositae, Cruciferae, Cyperaceae, Poaceae, Sparganiaceae and Typhaceae were identified as overwintering plant hosts of Chilo suppressalis larvae, a key pest of rice in northern Iran. From the collected host plants, two species including, Raphanus raphanistram and Eleusine indica are newly recorded from Iran as the host plants of C. suppressalis. The samplings indicated that the highest numbers of collected host plants were belong to the family Poaceae. Also, the results revealed that the larvae of C. suppressalis preferred three host plants of Xanthium pensylvanicum, Amaranthus spp. and Sorghum halopensae for overwintering.

In order to determine the critical period of weeds control in Allstar cultivar of sunflower, an experiment was conducted in experimental farm of Islamic Azad University of Tabriz, Iran, in 2007. The experimental design was a randomized complete block with three replications. The treatments were weed – infested and weed – free at 0, 2, 4, 6, 8, 10 and 14 weeks after sunflower emergence. Studied traits were hull weight to brain weight ratio, 100 grains weight, grain yield, oil percentage and oil yield. Results indicated the significant differences among treatments in most studied traits. Full season weed – infested treatment decreased up to 27.5% and 43% grain and oil yield in comparison to full season weed–free treatment, respectively. Based on fitted equations for weed–infested and weed – free plots, 1 to 9.5 weeks and 2.5 to 7.5 weeks after sunflower emergence were determined as critical periods of weed control with 5% and 10% yield loss, respectively.

In order to study the effects of some agronomic traits of rain-fed chickpea cultivars on yield and yield components in supplemental irrigation condition, a field experiment was conducted at Mahidasht Agricultural Research Station of Kermanshah province during 2007 croping season. The experimental design was split plot based on randomized complete block design with three replicates. supplemental irrigation treatments including control (I0), Irrigation at 50% flowering (I1) and Irrigation at podding (I2) were considered as the main factor and four chickpea varieties of Bivaniej Local, ILC482, FLIP93-93 and Hashem were arranged in sub factors. Measured traits were plant height, number of pods per branch, number of pods per main stem, number of pods per plant, 100-grain weight, grain yield and grain size. Results showed significant effect of supplemental irrigation on plant height, number of pods per main stem, number of pods per branch, number of pods per plant, number of seeds per plant, grain size, grain yield, 100-grain weight and biological yield. Based on the results, supplemental irrigation at podding stage was the most effective traetment in increasing yield and yield components. Yield and yield components increase were also higher in FLIP93-93 and Hashem cultivar than others.

Effects of seed inoculation with different concentrations of nitragin (2, 3, 4 cc and control) on germination and primary growth of rapeseed (Brassica napus L.), sesame (Sesamum indicum L.) and sunflower (Helianthus annus L.) was evaluated in a completely randomized design with three replications in Islamic Azad University of Tabriz. Based on the results, rapeseed inoculation with 2 cc nitragin increased radicle and plantlet length up to 110 % and 60 %, respectively, compared with control. When sesame seeds inoculated with 4 cc nitragin, radicle length reached from 38 to 75 mm (48% increase). Application of 2 and 3 cc nitragin could increase plumule length of sesame up to 31%, compared with control. Inoculation of seeds with 2, 3 and 4 cc biofertilizer increased germination rate of sesame up to 26 %, 48 % and 14 % respectively, and reached from 0.16, 0.19 and 0.15 to 0.13 germination per day. According to major role of seed germination rate in uniform emergence of field, it is recommended that sesame seeds were planted after inoculation with 3 cc nitragin. Effect of seed inoculation on sunflower plantlet length was significant and the highest plantlet length (42 mm) was observed in seed treatment with 4 cc nitragin. It seems that relative improvement of plantlet length in presence of nitragin could play an important role at uniform emergence of plants in field.

In order to evaluate agronomic attributes of six Azarshar red onion morphotypes, an experiment was conducted in Shabestar region, Iran in a randomized complete block design (RCBD) with three replications. Seeds of experimental onion landreces were collected under isolated condition and onion yield, bulb diameter, number of centers, dry matter percentage, number of edible layers, number of bulb scale, and percentage of twin onions were measured. Cluster analysis grouped the morphotypes into three clusters. However, grouping based on agronomic attributes showed no correspondence with the geographical pattern. Ssignificant differences in all studied attributes, except number of bulb scale, indicated diversity among Azarshar red onion morphotypes. According to the results, Azarshar red onion landrace is a potential resource of useful genes for breeding programs. The results revealed that the red onion morphotypes was not suitable for industrial processing due to the their low dry matter percentage and should be used in fresh-market. Furthermore, the correlation between measured attributes showed that selection of onions with larger diameter could be suitable in breeding for higher yield.