نشریه پژوهشهای زراعی ایران
سال یازدهم شماره 1 (پیاپی 29، بهار 1392)

This study carried out in a factorial layout on completely randomaized block design with three replications، to evaluate the above- and below- ground competition between sesame (Sesamum indicum) and pigweed (Amaranthus retroflexus)، and their impacts on sesame yield and yield component. The experimental treatments were all combination of crop-weed competition (shoot competition، root competition and root-shoot competition) and sesame plant densitys (1، 2 and 4 plant per pot). Plants were sown in plastic pots (24 cm diameter and 28 cm height) in year 2010، at feild of Ferdowsi University of Mashhad. For study the shoot competition of sesame-pigweed، the roots were separated by plastic when the pots were filled with soil before sowing the seeds. Three weeks after emerging، shoots of plants were separated vertical barrier (30 x 70 cm) for studing root competition. Results showed that competition treatments had a significant effect on seed weight per plant and yield components except 1000 seed weight. Among competition produced higher yield and yield components compared to othere treatments. However، sesame and pigweed biological weight in root-shoot competition was 2. 6 and 13. 7 respectively، that was higher than other competition treatments and was significant. Capsule number in main and sub branches، capsule number in plant، seed number in capsule and seed number in plant in complete competition treatment was 15، 2. 58، 17. 5، 43. 7 and 693. 89 respectively، that was higher than other treatments and differences among them was significant. Sesame density also had a significant effect on seed weight per plant and yield components. When low density were used (one plant)، yield and yield components was more، therefore in one plant per pot density biological weight of sesame was 3. 82 gr، and in higher densities the mentioned traits decreased significantly.

To study the effect of salinity on germination and threshold of barley germplasms two experiments carried out as a factorial arrangement based on completely randomized designin greenhouse and laboratory condition. In the first experiment 23 barley germplasms (17 wild and 6 improved barely cultivars) were investigated for germination index with four treatments of salinity (0، 100، 200 and 300 Mm NaCl) in three replications and in the second experiment the threshold salinity of 7 germplasms that selected from the first experiment were analyzed in five treatments (1. 3، 5، 10، 15 and 20 ds. m-1) with four replications. At the end of the first experiment،following factors were measured: germination percent،root length،shoot length،root fresh weight،root dry weight،shoot fresh weight،shoot dry weight،Na+ root content،K+ root content،Na+ shoot content،K+shoot content also threshold salinity، shoot length، dry and fresh weight، Na+and K+content was measured in the second experiment. The result showed that increased salt concentrations caused decrease final germination percentage (P≤0. 05). Some of germplasms showed high tolerance to salinity. The relative yield of dry weight indicated that H. vulgare،var. Afzal with 25. 24 ds. m-1andH. murinum (Ilam) with 16. 65 ds. m-1 which had the maximum and minimum EC50 value respectively between these germplasms. In this experiment the native cultivar had a highest tolerance with compared to the other cultivars that is likely contain genes for resistance to salt stress.

Ajowan is one of the endemic plants in Khorasan province، and there is a little information on its tolerance to cold stress. In order to study freezing tolerance of ajowan، an experiment was conducted in faculty of agriculture، Ferdowsi University of Mashhad، based on factorial-completely randomized design with three replications and three ecotypes of ajowan (Neishabour، Birjand and Torbat-e-Heidarieh) were imposed on eight freezing temperatures (0 (control)، -1. 5، -3، -4. 5، -6،-7. 5، -9 and -10. 5 °C). Plants were grown in natural environment till 4-5 leaf stage، then for freezing treatments transferred to thermo-gradient freezer. The cell membrane stability was evaluated by electrolyte leakage index (EL) and temperature for killing 50% of samples according to the electrolyte leakage (LT50el) was determined. Furthermore، survival percentage، leaf number and dry weight، temperature for killing 50% of samples according to survival (LT50su) and reduced dry matter temperature 50 (RDMT50) were determined after three weeks recovery in the glasshouse. Response of ajowan ecotypes for electrolyte leakage was different and birjand ecotype had the lowest %EL، whereas the slope of %EL in mentioned ecotype was lower than two other ecotypes. However there were no significant differences among ajowan ecotypes on LT50su. Decreasing temperature to -7. 5 °C reduced survival percentage of Neishabour and Torbat-e-Heidarieh ecotypes to lower than 20 percent، whiles in this temperature Birjand’s survival percentage was about 60 percent. It seems that Birjand ecotype with the lowest electrolyte leakage، the highest survival and dry matter and the lowest LT50su was more tolerant than two other ecotypes.

To evaluate the effect of different levels of nitrogen fertilizer and municipal compost on the essential yeild of savory pot experiment in 2009 was carried out in the Darab region. Different doses of compost was in four levels، including: zero C0:، 10C1:، 20C2: and 30C3: tons per hectare and nitrogen fertilizer include: zero N0:، 30N1:، 60 N2: and 90N3: kg of pure nitrogen from urea per hectare. Analysis of variance showed that the consumption of different amounts of nitrogen، compost and interaction between them on dry matter yield and height، percentage and yield of essential oil of savory، is statistically significant. Comparison of mean showed that treatment 90 kg N/ha along with 30 tons of municipal compost consumption per hectare (N3C3) with an average 50/8 g dry weight in pot greatest and treatments without N and compost (N0C0) and non-N with 10 and 20 tons of compost ha (N0C1 and N0C2) were mean 23/69، 23/42 and 24/63 g dry weight، the lowest plant dry weight were allocated to pot. N fertilizer and compost on the number of lateral branches per plant and nitrogen application on mean stem diameter was significant. N3 with an average 24/75 lateral branches and C3 with a mean 22/19 lateral branches، were the highest number of lateral branches per plant. N2C3 with mean of 2/13 percent of most essential oil produced. The most essential yield of the combination treatment N3C3، respectively. Generally produce more essential oil percent and to have more dry matter level N2C3 be seems appropriate.