نشریه پژوهشهای زراعی ایران
سال چهارم شماره 2 (پیاپی 8، پاییز و زمستان 1385)

It is well known that the host plant inoculation by native strains with high efficiency has a positive effect on plant yield and biological nitrogen fixation process. The main aim of this investigation was to based on salinity and drought experiments, four isolates of Sinorhizobium meliloti (S27K and S36K tolerant isolates, S109K semi-sensitive isolate, S56K sensitive isolate) were selected for plant inoculation which was under drought stress in greenhouse condition. This experiment was carried out by using a factorial model in completely randomized design. Results showed that inoculation of alfalfa plants with high salinity and drought tolerant of Sinorhizobium meliloti bacteria could increased biological nitrogen fixation process (symbiotic efficiency), percent crude protein and yield of alfalfa under salinity and drought conditions significantly. There were not any significant differences between S27K and S36K isolates and positive control (no nitrogen limitation). Symbiotic efficiency increased 3.4 times higher than alfalfa plants were inoculated by sensitive isolates S56K when alfalfa plants were inoculated by S27K and S36K isolates.

Salinity stress is one of the most important problems of agriculture in crop production in arid and semi arid regions. Under these conditions, in addition to management strategies, proper and adequate nutrition also has an important role in crop improvement. A greenhouse experiment was conducted to study the effect of 4 different irrigation water salinities (blank, 4, 8 and 12 dS m-1, prepared with 1:1 molar ratio of chlorides of calcium and sodium and magnesium sulphate salts.) and 5 different zinc applications (0, 10, 20, 30 mg Kg-1 soil and foliar application of salt of zinc sulphate) on yield, yield components and zinc concentration of wheat, using a completely randomized design, factorial with three replications. Plant height, spike length, 1000 grain weight, number of grain per spike, grain and straw yield was decreased by Irrigation water salinity. And all of these parameters were improved by zinc application except 1000 grain weight. Zinc absorption and concentration in straw and grain was decreased by Saline water compared to blank. And concentration of zinc significantly was increased in straw and grain by increase zinc application. The results indicated that, zinc application under low to medium salinity conditions improved growth and yield of wheat due to decreasing the impacts salinity.

Animal manure on soil prepares essential elements and increase water holding capacity and quality of plants. To study the effects of animal manure on yield and its components, nutrients absorption, chemical composition and its percentages on Cuminum cyminum this experiment was conducted at the agricultural researcher station of Zahak-Zabol, during 2003 – 2004 in a randomized complete block design with four replications. Animal manure significantly enhanced number of umbers per plant, number of seed per plant, biological and seed yield. Use of animal manure had not significant affect on Ca, Mg, Fe, P, K, Mn, Zn, and Cu and protein percentage in cumin seed but decreased Na concentration. Animal manure significantly enhanced cumin aldehyde and ρ-cymene and decrease β-pinene, γ-terpinene and α-pinene in cumin oil. A relationship or correlation exists between the main components of cumin oil. This study showed that animal manure enhances seed yield, oil percentage and qualitative chemical composition in cumin oil.

The effect of plant density and nitrogen fertilizer on canopy light interception and on flowering was investigated in hemp (Cannabis sativa L.) cv. ‘Kompolti’ Crop grown at initial densities of 50, 150 and 250 plants/m2 at the Mashhad and 30, 90 and 150 plants/m2 at the Shirvan. Nitrogen fertilizer was applied before and 45 days after sowing at a rates of 50 and 200 kg/ha at the Mashhad, and 50, 150 and 250 kg/ha at the Shirvan. Rate of canopy development increased with increasing plant density and nitrogen fertilizer in both sites. At the Mashhad, interception of 90% of light was attained at 380 to 665 degree days (base 2°C) from emergence for the crop grown at different densities. At Shirvan, rate of canopy development was slower. Interception of 90% of light was attained at 586 degree days from emergence for the crop grown at 30 plants/m2 and at 712 degree days for the crop grown at 150 plants/m2, probably as a result of cold weather. Nitrogen fertilizer in a similar way as plant density increased light interception. Maximum light interception did not depend on plant density and nitrogen fertilizer and was about 95%. In both sites, the flowering date was later with increasing plant density. Dates of 75% flowering for the initial densities of 50, 150 and 250 plants/m2 in Mashhad and 30, 90 and 150 plants/m2 in Shirvan were, respectively 26 August, 1, 6, 6, 11 and 12 September. Independent of plant density, canopy light interception started to decline at about 150 degree days after flowering, reaching 58 to 75% at about 700 degree days post-flowering. Morphological characteristics at both sites were highly correlated with plant sexual, plant population and nitrogen fertilizer. Highest stem, leaf and inflorescence yield were obtained in Mashhad at 250 plant/m-2 and in Shirvan at 150 plant m-2 when 200 kg N ha-1 in Mashhad and 250 kg N/ha in Shirvan was used. Above ground dry matter increased at both sites with increasing plant density and nitrogen supply. The results presented here can be used to account for the effect of a wide range of plant densities and nitrogen fertilizer for simulation of the course of light interception by a hemp crop.

Rotation can be used as an approach for weed management, because density and combination of weed seed bank may be affected by rotation. In this study effect of rotation in diversity and density of weed seed was studied in three rotation systems (fallow – barely, maize – barely and canola – barely). Results showed that fallow – barely rotation system have high population density in seed bank and highest amount of Shannon diversity index (H = 0.84). In canola – barely rotation system because of different herbicide uses and special traits of canola, population of weed seeds in seed bank was significantly lower that other rotation systems. Results showed that canola – barely rotation system because of combination special herbicide and agronomical and biological characteristic of canola, in comparison with other rotation systems is more successful in decreasing of weed seed bank.

An experiment was conducted in 2002-2003 using split-split plot arrangement based on Rondomised Compelete Block Design with three replications at Feiz Abad Agricultural Research Station of Qazvin, in order to study of planting patterns and corn densitis effect in competition with redroot pigweed. Main plots inclouded two planting pattern of corn (P1: single row and P2: double row), sub plots inclouded two corn densities (D1:7 and D2:10 plant/m2) and sub sub plots inclouded 4 weed densities (C1:0, C2:2, C3:6, C4:12 plant/m2). Sampling conducted in 2-weekly intervals and growth indices evaluated. Results indicated that with increasing of weed density CGR, TDW, LAI, number of seeds in row, grain and ear yield decreased but plant height increased. Also LAI, CGR, TDW, number of weed seed and seed,s weight of weed increased. By increasing in corn density LAI, CGR, TDW, ear and grain yield increased, but length and diameter of ear and number of seeds in row decreased. Also LAI and CGR of weed increased, but TDW was decreased. In double row planting pattern just CGR, LAI, TDW of corn were higher significantly than single row planting pattern. But single row planting of weed caused higher LAI, NAR, RGR, CGR and TDW of weed in comparison with double row planting pattern. In 2-way interaction, double row planting pattern and zero densities and 2 weeds/m2 had highest grain yield respectively. There were no significant differences for 3-way interactions but double row planting pattern 10 plant density of corn/m2 zero weed/ m2 had highest grain yield.

To study the effect of plant density on growth indices of four grain sorghum cultivars an experiment was conducted as factorial based on Compelete Randomized Block Design with 3 replications at Experimental Field of Birjand Azad University in 2003 growing season. In this study 4 grain sorghum cultivars including Sepideh, Saravan local, Payam and Kimia and 3 plant densities 100000, 180000 and 260000 plant/ha were investigated. The results showed superiority of Saravan local compare to other cultivars because of having maximum total dry matter, leaf area index, crop growth rate, relative growth rate, and net assimilation rate. The highest amount of leaf area ratio and specific leaf area were in Kimia and Payam cultivars, respectively. All of the above mentioned growth parameters were increased by increasing population denseity with exception of relative growth rate and net assimilation rate. From the obtained results Saravan local cultivar in density of 260000 plant /ha had the highest grain yield. The maximum relative growth rate and net assimilation rate were obtained in lowest density.

Safflower (Carthamus tinctorius L.) is an oil seed crop and because of its adaptability, it is widely grown in Isfahan provience. Appropriate soil fertility can increase seed yield and its quality. This study was conducted to investigate the effects of macro and micro-nutrients on agronomic traits of safflower. A split-plot experiment in a randomized complete block design with three replications was used in which the nine fertilizer treatments were applied in main plots and the genotypes of Arak-2811 and Isfahan-22 in sub plots. The results showed that applying the fertilizer for nutrient elements of N, P, K, Fe, Zn, and Mn had no significant effects on the studied traits. Despite no statistically significant effect of fertilizer treatment on yield components, seed yield/plant, seed yield and oil yield was observed, the variation of means for these traits was considerable. The minimum and maximum mean of all these traits were obtained for fertilizer treatments of P+K and NPK+Fe, respectively. Seed yield/plant, seed yield/ha and oil yield/ha for the fertilizer treatments had a variation of 12.91 to 20.22 g, 2601 to 3333 kg and 797 to 1046 kg, respectively. Increasing of seed and oil yield in NPK+Fe treatment was mostly due to the effect of N and Fe. The oil content of the seeds for fertilizer treatments varied from 32.6% to 32.02%. In case of using no fertilizer, the oil content of seeds was 31.28%. No significant interaction effect between fertilizer treatments and genotypes was observed for all the traits, indicating that the effect of fertilizer treatments was the same on both genotypes and it seems that the same fertilizer treatment can be recommended for different genotypes of safflower to increase oil yield.

Weed seed bank dynamics in corn, sugar beet and wheat plots in rotation with wheat were studied under conventional and ecological management systems during 2 years. The experiment was laid out in a split- plot design in a randomized complete block, where 3 crop rotations were assigned to main plots and 5 cropping systems including high–input, medium–input, low–input, integrated and organic systems were allocated to subplots. The results showed that crop species and weed management practices in different cropping systems significantly affected weed seed bank composition. However, weed seed bank dynamics were indirectly affected by crop rotation. The highest mean weed seed density and weed species diversity in soil surface layer was observed in organic system while high–input system had the lowest seed density. Weed seed density of soil surface layer in organic and low–input systems were twice of that in deeper soil layer. However, in high–input system weed seed bank was uniformly distributed over soil layers. The highest weed seed density was observed in continuous wheat plots where seeds were mainly accumulated at soil surface layer. Corn-wheat and sugar beet-wheat rotations led to a lower seed bank density and more uniform distribution of weed seeds in soil.

Although, various weed control methods have been developed, weeds pose a permanent threat to the crop production. A field study was conducted in 2004 at the Ferdowsi University of Mashhad Research Field to evaluate the effects of different weed managements and their integration on weed density and biomass and tomato yield. The experiment was designed as a strip plot based on complete randomized block design with three replications. Treatments were two tillage systems (reduced and conventional) and six weed management methods (herbicide, rotary cultivator, handweeding, herbicide plus rotary cultivator, herbicide plus handweeding, and handweeding plus rotary cultivator). The herbicide, handweeding, and rotary cultivator treatments were applied 2, 3, and 6 weeks after transplanting, respectively. The highest and lowest amounts of tomato yields were obtained in herbicide plus rotary cultivator and rotary cultivator, respectively. Density and biomass of broadleaved weeds was affected by different weed managements, and they were controlled by handweeding and its integration with herbicide better than other treatments. Different weed managements had no effect on grass weeds density, except by the end of growing season. Handweeding treatment and its integration with herbicide, also, controlled grass weeds better than the other treatments In conclusion, integrated treatments in comparison with single treatments decreased weed density and biomass and increased tomato yield. The least weed control and tomato yield was obtained in rotary cultivator treatment.

To evaluate the drought tolerance of new wheat genotypes to terminal water stress in field conditions, an experiment using a split plot design based on compelet randomaised block design with three replications was conducted in Torogh Agricultural Research Station (Mashad) in 1382-83. Irrigation treatments with two levels were allocated in main plots: I1- full irrigation (100% water use in different development stages) and I2- water stress (withdrawal of irrigation from anthesis stage to maturity with prevention of precipitation using mobile rain shelter). Number of 16 elite wheat genotypes suited for cold regions of Iran and Khorasan province (C-82) were allocated in sub plots. Results showed that, irrigation treatment had a significant effect on grain yield (GY), harvest index (HI), No. of spike per m2 (S.m-2), No. of grain per spike (G.S-1) and thousands kernel weight (1000 KW). There was significant differences between genotypes. C-82-5 was a high yielding genotype in both conditions (control and water stress) and had optimum level of HI, G.S-1 and 1000 KW. The tolerance of genotypes to water stress was evalovated with different drought tolerance indices, such as stress tolerance index (STI). Results showed that, C-82-5 was a high yielding genotype with more tolerance to terminal water stress.

Although botanical characteristics of saffron are well documented in the literature, there is little evidence on physiological aspects of this plant. Four separate studies were conducted to evaluate effects of duration and conditions of incubation period, weight of mother corm and different light / temperature regimes on aerial and corm criteria of saffron. Results showed that at the end of growth period, reduction in mother corm was more pronounced under natural condition compared with the growth chamber conditions (4.2g vs. 2.7g /corm). Incubation period of 120 days compared with 60 days caused more reduction in corm size. A combination of 120 days incubation in growth chamber and bigger size of corms caused more rapid emergence of aerial parts and an increase in leaf area. Corm size had no effect on length of planting to emergence of aerial part, leaf area and number of active buds on corms but incubation of corms in growth chamber promoted emergence of aerial parts significantly. Length of planting to emergences of aerial parts was longer with 120 days compared with 60 days incubation. However, with application of water to corms this event was shorter. Light / temperature regimes had a significant effect on length of emergence of aerial parts, root and aerial dry mater, leaf area and number of active buds on corms and increasing light period for 6.5 to 16 hours increased all these parameters. When corms were exposed to light regimes of 16/8 (light and dark) 33% of corms initiated flowering compared with 75% for corms exposed to natural conditions. Corms exposed to light regimes of 6.5/5.5 did not initiated flowering.

In order to determine of genetic variation in germplasm of 120 watermelon accessions, a field trial conducted at agricultural and natural resource research center of khorasan. These Accessions with four commercial cultivars as control were planted in agnomental design with six replications. 15 quantitative morphological traits were measured and some statistical parameter and analysis include of Mean, Coefficient variance, cluster analysis, correlation regression coefficients were determine for this traits. yield, Sugar percent, time between flowering and ripping, fruit length, fruit width, fruit mass to fruit weight ratio, fruit skin to fruit weight ratio, seed weight to fruit weight ratio, 100 seed weight, seed length, seed diameter, seed width were the most useful traits for identifying of genotypes from each other. A one side analysis of variance was performed for different regions genetic diversity detection, which indicated a significant difference between regions for all traits except fruit Ph and fruit skin thickness. Cluster analysis divided genotypes into eight groups based on quantitative data. Correlation analysis between traits showed a significant relation between yield and all traits except fruit ph, time to flowering and seed fruit length.

Geostatistical techniques were used to characterize the spatial relationship between Hordeum spontaneum and Cardaria draba seedling and seed bank over the course of one growing season (2004-2005) in three saffron fields, located in Southern Khorasan, Iran. The density and spatial distribution of weeds varied widely with fields. The emergence percentage was higher for Cardaria draba than for H. spontaneum in all fields. Semivariograms showed spatial autocorrelation in seed bank and seedling populations of H. spontaneum and C. draba in all fields. Cross-semivariograms showed moderate to strong (63.3 to 94.7%) and strong spatial continuity (78.4 to 95.4 %.) between seed bank and seedling population densities of H. spontaneum and C. draba, respectively. Grey-scale field maps of C. draba seed banks corresponded visually to maps of seedling populations and could have been used to target control efforts, but visual correspondence between H. spontaneum seed bank and seedling maps was poor. Seed bank and seedling mapping may be useful for site-specific management, but additional information is needed to understand variation in the relationships between these two populations over time and space.

In order to select optimum spatial arrangement (row and plant space) and its effects on grain and biological yield of pea (Pissum sativum L.), Spring Pea-2 line, a 2-years (2002-3, and 2003-4 growing season) field experiment were conducted in Agricultural Research Station of Kohdasht in Lorestan Province. The experimental design was a split-plot with 4 replications. The experiment had 2 factors: row spacing at 2 levels (30 and 50 cm) as main plot, and plant space at 4 levels (5, 10, 15, and 20 cm) as subplot. Increase in row space from 30 to 50 cm, and plant space from 5 to 20 cm, reduced pea pod number per unit area by 30, and 67 %, respectively. Pea biomass and seed production showed an asymptotic respopnse to crop density. On the basis of hyperbolic function, maximum grain yield for 2002 and 2003 years were estimated as 2738 and 1067 kg/ha, respectively. On the basis of 2 years results, the maximum grain yield (1050 kg/ha) and biomass (3001 kg/ha) was belonged to the 30×5 cm spatial arrangement with density of 67 plants/m2. Therefore, this spatial arrangement is recommended for grain or forage production in dryland situation of Lorestan Province and other similar climates.

To study the germination characteristics and cardinal temperatures of Nepeta binaludensis a laboratory experiment was conducted. In this experiment the effects of seven constant temperatures including 5, 10, 15, 20, 25, 30 and 35°C and three alternate temperatures including 5/10, 10/20 and 20/30°C on germination percentage and germination rate was studied. The highest germination percentage was obtained at temperatures between 20-30 °C while the highest germination rate was recorded at 20 °C. Alternate temperatures have also a significant effect on germination characteristics of this species. The highest germination percentage and germination rate were recorded in alternate temperature of 20/30 °C. Base, optimum and critical temperatures were 7.4-9.9, 22.9-23.7 and 35.7-37.1°C, respectively.