PLANT AND ECOSYSTEM
Year:2010 | Volume:5 | Issue:20|Papers Count:8

Weed s are the most important factors that decrease yield of crops. Weed species of field corn of Qazvin collected and identified on 2005, then their density and frequency were determined. The results of this study showed that 31 species belong to 17 genera disturbed in Qazvin corn field. The most frequent weed species were Amaranthus blitoides L., Amaranthus retroflexus L., %; Portulaca oleracea L and Setaria viridis L. respectively The life forms of Terophyta and Hemichryptophyta are the best frequent life form of Qazvin province. The most of species had Irano –Touranian distribution.

Cupressus macrocarpa or Monterey cypress grows on the south, northwest of Americ a and California. Monterey: Cypress is an evergreen conifer that can get over 100 ft (30 m) tall with a trunkdiameter of 8 ft (2.4 m). Besides the wood prod uct, gardners use this species with brunch praning. Recent decades flower producers imported this species to Iran.Cutting method is the most suitable method of reproducing of this tree. To increas the sapling prod uction in one area different places and soil componets with split plot method were used, there were 3main treatments for space production: 1-green house without temperature with 2 meter height 2- green house without temperature with 1 meter height 3- open space.In Secodary treatment there were four kinds of soil such as: (sand, loam, 1/2 lome+1/2 mold+1/3 sand+1/3 mold+1/3 forestsoil) in every flowerpot 10 * 7 cm two cutting hemi wood placed. In every method (space production) 240 flowerpot with 480 cutting and in three methods 720 flowerpot and 1440 cutting at the end of septe mber was provided. After twelve month results showed that in main treatment (production space) at 5% and secondary treatment (different soil componets) 1% was significant. The most persent rhizogencsis was related to main treatment 54.15% and secondary treatment 54% and the least percent was related to open space (22.2%), and sand (16.4%).

In soil of the arid and semi - arid regions of Iran which is very salinity is very wide spread, salinity is the most important limiting factor. Application of biological systems is one of most suitable methods for salinity rehabilitation in these areas. A research project was conducted to solve a part of the salinity problem in Chah- afzal region consisting of five treatments based on a randomized systematic statistical design. The treatments consisted of five identical areas with different Atriplex cover and management system v: 1. control area (no Atriplex vegetation cover), 2. Atriplex vegetation cover without pruning.3. Atriplex vegetation cover with every year pruning, 4. Atriplex vegetation cover with pruning in every two year intervals, 5. Atriplex vegetation cover with every three year pruning intervals. The soil chemical parameters consisted of EC, pH, Na and SAR Were measured in three different soil depths of 0-20, 20-40 and 40-80 centimeter. The results showed that Atriplex lentifomis significantly decreased soil salinity to 40cm of soil depth. However, no significant effects was observed by pruning on measured soil parameters. Due to the ability of this spices in soil salinity decrement along with its potential characteristics for forage production, it could be recommended for rehabilitation of degraded rangeland in similar ecological regions.

In order to Study the physiological responses of two barley cultivars to salinity stress, a 4-replicated CRD greenhouse experiment was conducted at the college of agriculture, The Islamic Azad university of Fasa, 2006. The treatments consisted of two barley cultivars: Sarvestan and Reyhan and five salinity levels: o, 85, 171, 256 and 342 mM. NaCl. Seed culturing was done in greenhouse and plants irrigation with the help of Hoagland nutrition solution. Total dry weight, stem and root length, total leaf chlorophyll, proline in shoots and Na+, K+content in shoots were measured at the final leaf growth stage. Results showed that the total chlorophyll and dry weight decreased with increasing salinity levels. The reductions were lower in Sarvestan than Reyhan. A lower Na+and higher K+in Sarvestan compared to Reyhan were observed under high level of salinity. Proline content in shoots increased with increasing salinity levels. The proline content were higher in Sarvestan than Reyhan. Results showed that the effects of salinity stress on some of the physiological characteristics were lower in Sarvestan compared to Reyhan. Since a higher tolerance to salinity in Sarvestan was apparently associated with a lower concentration of Na+and a higher K+of shoots, this trait could probably be used for yield improvement of barley cultivars under saline conditions.

Drying is one of the most important step in raisin processing. During this step, initial moisture content is decreased up to 15 – 17 percent (d.b).In this research, the effect of two-tempreture and pretreatments on time and drying rate of Thompson seedless grape was studied. Drying was in two steps: First step; temperature at four levels of 50, 60, 70, and 80 oC and secound step which samples were placed at two temperatures. In this step, samples were placed at 80 oC and while moisture content was reduced to 50%, temperature was reduced to 70, 60 and 50 oC. Four pretreatments including hot water, %5 potassium carbonate, %0.4 olive oil, %0.5 sodium hydracids and no pretreatment was performed.According to the results of the ANOVA, factors such as temperature, two-temperature and pretreatment have significant effects on drying time and average drying rate. Drying time of grape with two-temperature in comparison with drying time of constant temperature was decreased, up to 61% for some pretreatment. Maximum and minimum activation energy were determind 893.9, 4538.8 kj/kg.

In order to reach stable development, it is necessary to consider productivity in all dimensions, including agro-organizations which agricultural machineries are involved by many of these organizations. Quantitative and qualitative study on function of current machineries of tillage and cultivation is important for several factors: first one is economic factor, second one is accessibility and easy usage by farmers of each region and the third one, the most important, is the protecting its structure - earth - against erosion and destruction. Different models of tillage and cultivation (18 models) are considered by this study consisting of several agricultural machineries.Different methods for tillage after harvesting feeding corn in order to cultivate water fall wheat as main factor in 6 levels were evaluated and compared as below: - Moldboard plow+two times disks+Leveler; - Moldboard plow+one time disk+Leveler; - Chisel plow+two times disks+Leveler; - Perpendicular, two times disks+Leveler; - Rotivator+Leveler; - Chisel plow+Rotivator+Leveler; And different methods for harvesting water fall wheat as secondary factor in three levels were evaluated and compared: - Grain drill centrifuge+furrow opener - Taka grain drill+furrow opener - Hamedan grain drill.Results of conical penetration index, weight average of earth and functional components of yield have shown that the best main treatment is Chisel plow+two times disks; and the secondary treatment is Hamedan grain drill with total time of 5.6 hours in one hectare in order to prepare and cultivate earth.

To study the competitive effects of redroot pigweed (Amaranthus retroflexus) and lambsquarter (Chenopodium album) on potato, an additive experiment was conducted in the spring of 2004 and 2005 in split-split plot based on randomized complete block design with 4 replications at the Seed Potato Production Station of RAN in Firouzkooh. Treatments included 2 weed species in main plots (Amaranthus retroflexus and Chenopodium album), weed density in sub plots (2, 4 and 8 plants per meter of row) and relative time of weed emergence in sub-sub plots (8 and 4 days prior to potato and the same time with potato emergence in 2004 and the same time with potato, 2 and 4 weeks after potato in 2005).Results showed that both weed species reduced biological yield. TDM reduction in 2005 were 27.5 and 25.1 percent less than 2004. Redroot pigweed caused 33.8 and 38.1% more potato dry matter reduction than lambsquarter.

To evaluate the growth trend of three chickpea varieties, this experiment was conducted at field experiment of Mahidasht near Kermanshah. This experiment was carried out in randomized complete block design in four replications in spilt plot arrangement. The main factor was planting date and variety was considered as a subplot factor. Varieties included ILC482, Hashem (Flip84-48 C) and Arman. And sowing time was November 11 (Autumn), December 11 (Winter) and March 11 (Spring). For studying and surveying the chickpea growth trend once in fifteen days after becoming green to getting physiological takes action for sampling near each plot in surface is equivalent to 0.125 m2 after every sampling in the proporting of measuring physiological indexes such as dry matter accumulation, leaf area index, crop growth rate, relative growth rate were taken action. With delaying in planting (Spring) the weight of dry Shoots decreased. In the riew of dry matter accumulation of leaf, ILC482 had preference over the other varieties in December 11 and the highest dry matter accumulation of stem with 4.8 g in November 11 belonged to Hashem (FLIP 84-48C), generally the greatest weight of dry total plant weight with 12.6 g related to November 11 in Arman variety. Studying the Leaf Area Index in different variety Showed that the greatest Leaf Area Index with 3.1 belonged to Hashem (FLIP 84-48C). Delaying in sowing time, decreased Leaf Area Index too, so that the least amount of this character with 2.4 was shown in March 11. The greatest amount of CGR belonged to Arman variety in November 11. The maximum and minimum amount of RGR belonged to Hashem (FLIP 84-48C) and Arman variety and in different sowing time, the greatest RGR belonged to March 11, at this situation maximum amount of mentioned character was 67% g.g.day.