پژوهش های زراعی ایران
سال:1384 | دوره: | شماره: |تعداد مقالات:10

Because of importance of castor bean oil in different industries and limited water resources in many parts of Iran, an experiment was conducted to determine the effect of irrigation intervals and plant densities on grain, oil yield and yield components of castor bean, at Experimental Station, College of Agriculture, Ferdowsi University of Mashhad. Four irrigation intervals (one, two, three and four weeks) and four plant densities (1, 2, 3 and 4 plants per square meter) were compared in a split arrangement based on completely randomized block design with four replications. The plant characteristics were studied in terms of plant height, inflorescence height, the first inflorescence height from soil surface, inflorescence number, branch number, number of capsule per plant, number of grain per plant, biomass per plant, 1000 grains weight, grain yield, harvest index and oil yield. Result showed that the effect of different irrigation intervals was significant on all of characteristics under study except harvest index and oil percentage (P<0.01). Height of plant, 1000-grain weight, grain yield, harvest index and oil percentage were not influenced by different plant densities, but plant density had significant effect on other traits. The highest grain yield (1.16 tons/ha) and oil yield (0.54 tons/ha) were observed at one week irrigation interval. Among all treatments, four plants per square meter and two weeks irrigation interval had the highest grain yield (1.4 tons/ha) and oil yield (0.69 tons/ha).

To evaluate the interference of Red Root pigweed on growth indices of soybean cultivars an experiment was carried out in Research, Breeding and Providing of Seedling and Seed of Karaj institute during growing season of 2002. The experiments was established as a completely randomized block design in a factorial arrangement of three soybean cultivars (L11, Clark, Pershing (Sahar)), five pigweed density (4, 8, 16, 32 plant. M-1, plus a pigweed-free control). Pure pigweed planting in 4 density consisted of (4, 8, 16, 32 plant. m-1) was considered in any replication. According to variance analysis results, pigweed caused reduction of soybean dry matter yield, leaf area index, leaf area index duration, crop growth rate and relative growth rate significantly. The maximum of dry matter yield, leaf area index, leaf area index duration, crop growth rate and relative growth rate in each three soybean cultivars reduced to control with increasing pigweed density. The maximum dry matter yield, leaf area index average, leaf area index duration and crop growth rate average in control treatment of soy bean cultivars in growth duration was concerned to Pershing (Sahar) cultivar. The maximum relative growth rate average in control treatment of soybean cultivars in growth duration concerned to L11. The maximum of reduction rate of dry matter yield and leaf area index average of soy bean cultivars to control occurred in Clark cultivar and its minimum occurred in Pershing (Sahar) cultivar. The maximum of reduction rate of leaf area index duration and crop growth rate average in soybean cultivars to control occurred in Pershing (Sahar) cultivar and its minimum occurred in L11. Regarding to results probability pigweed with reduction of leaf area index, leaf area index duration decreased soybean dry matter yield.

The effect of salinity on nitrogen absorption and leaf chlorophyll content of wheat (cv. Falat) was studied in two separate greenhouse traits, both in a completely randomized block design with three replication. Three levels of nitrogen (0, 1.19 and 5.94 g Urea/pot) and three levels of salinity (0, 150 and 300 mol/m3 salts) were used as treatments. Salinity conducted by combining sodium and calcium chloride in a 1:10 molar ratio and pots were irrigated with modified Hogland solution in close system. Leaf chlorophyll and nitrogen contents, stomatal resistance, specific leaf weight (SLW) specific leafnitrogen (SLN) were measured at booting and anthesis stages. The results showed a high correlation between SPAD reading (leaf chlorophyll) and leaf nitrogen content and SLN. Leaf nitrogen content reduced but SLN and stomatal resistance increased by increasing salinity levels. SPAD reading increased up to salinity levels of 150 mol/m3 but reduced at higher salt concentration. Adjusted SPAD reading on SLW (SPAD/SLW) showed higher correlation with salinity levels compared to unadjusted SPAD reading and may used as indicator for severity of salt stress.

In order to evaluate the effect of irrigation regimes on yield and growth parameters of cumin (Cuminum cyminum) an experiment was conducted in Mashhad, Iran, during the years 1998- 2000. Six irrigation treatments were used as:T1:No irrigation during growing period (rainfed).T2: One irrigation during flowering stage.T3: One irrigation during seed formation.T4: Two irrigations during growing season; one at flowering stage and one at seed formation. T5: Three irrigations during growing season; one after germination, one at flowering and one at seed formation stage.T6: Full irrigation during growing season.During the growing season, treatments of rain fed and full irrigation received 185 and 350 mm of water respectively. The results showed that by reducing numbers of irrigation at various treatments, plant water potential is also decreased. It reached to -30 bars without showing any sign of wilting at T1 as compared to -15 T6 Seed yield, number of umbels per plant and number of seeds per umbels was not significantly different at 5 percent level. However, treatment T6, showed to have least weight of 1000 seeds and harvest index and highest total biomass. Differences between weight of 1000 seeds of T1 and harvest index of T3, T4, T5 and total biomass of T3, T2, T3, T4 were significantly different with treatment 6 at 5 percent level. The overall results showed that in climatic condition of Mashhad, Cumin need not to be irrigated in years with rainfall close to average.

Symbiotic and phosphate solubility efficiency of 45 isolates of Rhizobium leguminosarum b.v. viciae isolated from Gorgan and Nyshabour were investigated in the laboratory conditions. The results showed that all isolates did not have the ability of inorganic phosphate solubility in solid media but they showed it in liquid media. All isolates had the ability of organic phosphate solubility. Isolates of R. leguminosarum biovar viciae had different symbiotic efficiency and it ranged from 5 to 500 % among them. Isolates R65G and R59G isolated from Grogan and RJON isolated from Nyshabour showed the most symbiotic efficiency. Regarding the results of organic and inorganic phosphate solubility and symbiotic efficiency, isolates of R65G, R59G and R30N were selected as superior ones in this experiment.

In order to evaluate inoculation effects on bean (Phaseolus vulgaris L.) cultivars with different strains of Rhizobium legominosarum biovar phaseoli, a spilt plot experiment in randomized complete block design was conducted in the field at ShahreKord in 2002. The factors were four bacterial strains: L-78, L-47, L-125, 1-109 and plus nitrogen control (100 kg Nitrogen/ha) and a control plot (without inoculation) in main plots and three cultivars bean: local shahrekord (spotted bean), Talash (spotted bean) and local shahreKord (red bean) in subplots. The results revealed that there were significant differences among factor A in grain yield, weight of pod per plants, number of pods per plants, number of seeds per pods, number and weight nod at 50% flowering (50 days after emergence), nitrogen concentration of leaf and stem and percent of nitrogen fixation. Treatment of inoculated seeds with L-125 strain and control demonstrated the highest and lowest grain yield, respectively. The results showed that all treatments were capable of nodulation. However, strains L-109 gave highest nodule dry weight and percent of fixed N2. An efficient symbiotic was achieved with strain L-109, since total N content of plants inoculated with these strains was similar to that of plants supplied with N -fertilizer treatment.

In order to investigate the response of two species of P. ovata and P. psyllium to water deficit and manure, an experiment was conducted at the Agricultural Research Station, Ferdowsi University of Mashhad, in April 2002. For this purpose a split-factorial experiment based on completely randomized block design with three replications was used. Three irrigation intervals (every 10, 20 and 30 days) allocated in the main plots and three levels of animal manure (5, 10 and 15 tons/ha) and two species of plant a go in factorial arrangement were as sub plots. Criteria such as plant height, spike length, number of spikes per plant, number of seeds per spike, 1000- seed weight, straw and seed yield were measured accordingly. Three quality characters namely amount of mucilage, swelling factor and swelling rate per gram mucilage were also measured.The results indicated that spike length and seed yield was significantly affected by irrigation intervals. The highest seed yield in P. ovata and P. psyllium was obtained in irrigation intervals of 20 and 10 days, respectively. There was no significant effect on other criteria by irrigation intervals. Effect of animal manure was only significant on seed yield. Seed yield was higher with application of 5 tons/ha and 15 tons/ha in P. ovata and P.psyllium, respectively. There was no significant correlation between the amount of mucilage, swelling factor and 1000-seed weight. However, the highest amount of mucilage were obtained in irrigation intervals of30 and 10 days in P. ovata and P. psyllium respectively, maximum swelling factor with irrigation in 30 days interval and the highest swelling rate per gram mucilage in P. ovata and P. psyllium by irrigation intervals of 20 and 10 days, respectively. In water deficit condition and low-input agricultural systems it seems that P. ovata is more resistant species compared with P. psyllium.

Understanding agricultural biodiversity is the first step in determining the effects of intensive and monocropping systems and use of high yield cultivars on sustainability of agricultural systems. For this purpose biodiversity of fruits and vegetables in Iran was studied. Results indicated that many fruits and vegetables are cultivated in country, and therefore the number of cultivated species or species richness is considerable. Shannon index indicated that diversity of these crops is not proportional to species richness, which caused from unevenness distribution of cultivated land between crops, and possibly, high monoculture with regard to climatic conditions. Shannon index for fruits and vegetables in different provinces was rather high. However, due to lack of data on number of varieties cultivated, biodiversity at variety level which is an important index was not calculated.

In order to investigate the effect of water stress and defoliation on Zataria multiflora, Ziziphora clinopodioides, Thymus vulgaris and Teucrium polium, an experiment was conducted under greenhouse conditions. Treatments were combination of four water stress levels (-0.3, -5, -10,- 15 bar) and three defoliation levels (0, 25, 50 percent of foliage removal) arranged in a completely randomized desing with 4 replications. For imposing drought levels, percentage of soil moisture was determined in different water potential is by pressure plate method, and pots were weighted daily and the amount of water lost was added to each pot. Criteria such as SPAD readings, stomatal resistance, canopy temperature, leaf/stem ratio, specific leaf weight, percentage of dry leaves and root/shoot ratio were measured. Water stress increased SPAD readings in Ziziphora clinopodioides, specific leaf weight in Thymus vulgaris and Ziziphora clinopodioides, canopy temperature in Thymus vulgaris and Teucrium polium and percentage of dry leafs in Zataria multiflora and Teucrium polium significantly. Defoliation reduced SPAD readings in Zataria multiflora, Ziziphora clinopodioides and Teucrium polium, specific leaf weight in Zataria multi flora, Thymus vulgaris and Ziziphora clinopodioides and leaf/stem ratio in Zalaria multiflora significantly. A negative correlation was observed between leaf/stem ratio and different levels of water stress for all species. With increasing defoliation levels, root/shoot ratio was reduced in Zataria multiflora and Thymus vulgaris and increased in Teucrium polum and Ziziphora clinopodioides. Also, root/shoot ratio showed a positive correlation with different levels of water stress. Generally, Ziziphora clinopodioides was most resistant species and Teucrium polium most sensitive species to stress.

In order to evaluate wild mustard competitive effect on winter wheat, an additive series experiment was conducted in 2000-2001 at Agricultural Research Station of Mashhad University. The experiment had 3 factor: wheat seed rate (175, 2 I5 and 255 kg/ha), nitrogen rate (150 and 225 kg/ha), and a range of wild mustard densities. Hyperbolic functions were used to describe yield-weed density relationship. Increasing wild mustard density had a negative, asymptotic - type effect on wheat biomass and grain yield. By increasing wheat seed rate, in optimum nitrogen rate, maximum wheat biomas loss has reduced about 51 %. Maximum yield loss has increased from 42.1 % to 50.4 %, as nitrogen rate increased from optimum to upper optimum rate of wheat. By increasing of wheat seed rate from 175 to 255 kg/ha, maximum tiller number reduction due to high densities of wild mustard, has decreased by 54 %. Reduction of fertile tiller number was mostly occurred at presence of high nitrogen level, thus, reduction of fertile tiller number compared to control in N1 was 18%, while in N2 has increased to 30%. Wild mustard competition has reduced wheat seed number per ear 30% in compare to weed free control. Results show that wheat 1000 seed weight was more affected by nitrogen rate than plant densities. Apparently, in competition with wheat, wild mustard was better able to utilize the added nitrogen and thus gained a competitive advantage over the wheat.