فصلنامه گیاه و زیست بوم
پیاپی 7 (پاییز 1385)

Among the wheat bunts, wheat common bunt (CB) caused by Tilletia laevis Kuhn. is one of the most important wheat diseases which annually causes significant yieldlosses. In years 2004 to 2006 for evaluation of resistance in rainfed durum wheat advanced genotypes to CB, 9 genotypes were tested under artificial infection with teliospores of 11 collected isolates of T. laevis from Kermanshah province, west Iran. Response of each genotype to CB isolates in two years successively was recorded as the percentage of infected spikes at maturity stage. Infection lesser than 5% was considered as resistance. Consequently, G1252, Chi/Brch, Syrian-4, Heidar/Mt/Ho and Zardak genotypes had resistance to all of the isolates and Syrian- 1 showed moderate resistance to only 11 isolate and it was resistance to others.These genotypes with low degree of susceptibility to CB, were the best resistantgenotypes. 99-GBM and Omgenil-3 with the highest degree of susceptibility were the most susceptible genotypes. Multipathotype test by differential standard genotypes revealed that probably some of the promising resistant genotypes are Probably carrying Bt1, Bt4, Bt6, Bt9, Bt10, Bt11, Btp, Bt12 and Bt8,9,10 resistancegenes, but for more confirmation test of Allelism must be carried out. Other advanced genotypes with different pattern of susceptibility and resistance perhaps have unknown new resistance CB genes.

In order to investigate the relationship between deficit irrigation - transplanting in Tarom-Mahali cultivar on population density of rice stem borer and crop yield, an experiment was conducted as randomized complete block design with 7 treatments (various irrigation regimes) at 3 replications. Samplings were conducted after 2 weeks of transplanting, regurarly (every 15 days). In each sample, 5 hills in one plot were selected randomly and then infected and non-infected tillers were counted. The rate of rice plant infection was low at sampling and the difference was not significant before and after the first spraying; but infection before and after second spraying and also treatment's interaction were significant at 1% and 5%, respectively. Dead heart of plants was not different significantly in the studying years but this factor was significant between the treatments (different irrigation regimes) at 5%. Also any significant difference between the treatments was not observed. The research indicated that plant infestation was rather increased with sampling in different growth stages but low infestation and data for ANOVA are related to: 1. Low population density of pest (C. suppressalis), 2. Delay in transplanting of rice, 3.Asynchronisation between pest and host plant's phenology at the first generation ofthe pest, 4. Small plot areas. Although in this research, irrigation regimes had not any effect on population density of Rice Stem Borer, the study must be conducted inthe field condition for alogic and recommendable conclousion.

In this experiment, the effect of ABA and Calcium ion on thermotolerance of corn seedlings and its relationship with antioxidant enzyms was investigated. ABA treatment significantly increased thermotolerance in maize seedlings. Pretreatment of maize seeds with CaCl[2] solution, which raises calcium content of maize seedlings, further enhanced the ABA-induced thermotolerance. In contrast, pretreatment with the Ca[2+]chelator EGTA, which lowers calcium content of maize seedlings, decreased the ABA-induced thermotolerance. In addition, pretreatment with the plasma membrane Ca[2+] channel blockers La[3+] and verapamil, which are expected to inhibit the influx of extracellular Ca[2+] into cells, also weakened the ABA-induced thermotolerance in maize seedlings. However, the calmodulin antagonists W7 and CPZ had little effect on the ABA-induced thermotolerance Measurement of activities of the antioxidant enzymes SOD, CAT, APX and GPX and the level of lipid peroxidation (in terms of MDA) indicated that heat stressinduced an oxidative stress in maize seedlings. ABA treatment enabled maize seedlings to maintain higher activities of these antioxidant enzymes and a lower level of lipid peroxidation at normal culture temperature and under heat stress. Ca[2+] pretreatment further enhanced the ABA-induced increase in SOD and APX activities and lowered the heat stress-induced lipid peroxidation in the ABA-treated seedlings, but EGTA pretreatment had an inverse effect. These results suggested that the ABA-induced thermotolerance is mediated by Ca[2+] and requires the entry of extracellular Ca[2+] into cells across the plasma membrane.An antioxidant enzyme systems cause the increase in the ABA and decrease of the induced thermotolerance.

The essential oils from the leaves of Eucalyptus gillii and E.leu-coxilon were isolated by hydro distillation in two fractions and analyzed by GC/ MS.The oil consisted mainly of monoterpenes and sesquiterpenes. The major components found in the oil of E.gillii respectively for fractions of 1 and 2 were 1,8-cineol (89.07-77.6%), alpha-pinene (4.5-11.5%) and Viridiflorol (0.65-5.39%) and for E.leu-coxilon respectively 1,8-cineol (78.13-36.77%), alpha-pinene (10.44-26.77%) and Viridiflorol (0.0-11.5 %)

The effect of different concentrations of organic (urea) and inorganic (nitrate and ammonium) nitrogen sources on survival, growth and pigment composition (carotenoides) of green algae scenedesmus sp, has been studied at limited irradiance and without carbon dioxide addition. specimen was sampled from paddy–fields of Golestan province and after purification was treated with different amount of urea (M, L, JQ mm), nitrate (Land JQmm), and ammonium (Jand Mmm) under continuous JLQQlux irradiance. No carbon dioxide was added to culture except of usual aeration. Growth was measured with turbidity ODRLQ and pigment analysis was invivo and invitro too. Results showed that we can see the highest rates of growth in nitrate cultures as a whole. Organic nitrogen specially at higher concentrations cause possibly stress in the medium. JQmm of nitrate and J mm ammonium cause relative better growth. Carotenoides show no significant changes comparing different concentrations of nitrate. It seems that active carbon dioxide concentration mechanism cause survival of the specimen at limited carbon dioxide condition.

Drought is one of the worst chronic and the most harmful natural disasters, and in recent decades, it has been the large frequency natural disaster affected human population. Drought in world climatic researches is one of the main issues that is widely considered, but in Iran it is considered less than other countries. The aim of this study is to determin the best method for drought intensity evaluation among the percent normal methods, deciles method and standard precipitation index. In this case first 40 synoptic stations in the country that have 37 years data from 1966-1967 to 2003-2004 selected, and by using the above three methods, the number of drought years for each station is defined, and then by using regression analysis, the best method for drought intensity evaluation in Iran climatic condition is determined. Results showed that to determine the drought intensity in Iran and the climatic conditions for 12 months scale, percent of normal is the best one.

The area of Study was located in 50 km of northwest of kaleibar and 8 km of Aras river. This area has 38 50 38 - 52 north latitude and 46 44œ - 46 46œ east longitude. Average altitude is 1100 meter from sealveve. The region is bounded to Kalaleh village from north, to Vaigan village from east side, to Elgeneh Chay river from South and Teymour Baigloo village from west side. Rich amount of flora are showed suitable ecological condition and this flora be effected from diversity of climate and soil. Based on growth season and vegetation period all of the plant species were collected from region and determinated. The results were showed that this area has 220 species, 170 genuses and 61 families. We used from Raunkier Danish botanist category. Category of biological forms was done based on the position of live bud from soil surface. This study were showed that this area has 100 Hemicryptophyte species, 58 Phanerophyte species, 43 Therophyte species, 13 Geophyte species, 6 Camephyte species and vegetation physiognomy is with Phanerophyte plants. This ratios change in various ecological regions so as we can determine four climates: Phanerophytic humidity temperate regions, Hemicryptophyte moderate region with partial arid, Terophytic temperate regions and moderate with long arid season and Chamaephytic high width and high mountains. Based of carried out studies and said ratios Arasbaran region was placed on hemicryptophyte with moderate partial raid region. These biological forms include 45, 26, 19, 6 and 3 percent of all species respectively.