Iranian Journal of Crop Sciences
Year:2009 | Volume:11 | Issue:2 (42)|Papers Count:9

To study the effects of phytohormone and explants on the callugenesis and regeneration of Sainfoin (Onobrychis sativa L. var. Chadegan) an experiment was conducted in the biotechnology laboratory of Sciences and Research Unit, lslamic Azad University, Tehran, Iran in summer and spring of 2006. In this experiment, two phytohormones (2,4-D and BAP) and 4 explants (cotyledon leaf, apical meristem, stem, and root) were used. The highest number of callus was obtained on the MS medium containing 2,4-D (4 mg.l-1) + BAP (1.5mg.l-1) + apical meristem explant and 2,4-D (2mg.l-1) + BAP (1mg.l-1) + apical meristem explant with means of 1.77 and 1.76 callus, respectively. The highest regeneration was obtained in MS medium containing BAP (4 mg mg.l-1) with mean of 1.6 regenerated plants. A new method for in vitro micropropagation of Sainfoin (Onobrychis sativa Var Chadegan) was developed. Seedlings with root were transferred to greenhouse and continued growing.

In order to study the response of canola to plant densities of mustard (Sinapis arvensis L.) with emphasis on agronomic control in Ahwaz condition, an experiment was conducted in 2006-2007 cropping season at Ramin Agricultural and Natural Resources University. The experimental design was split plot arrangements in a randomized complete block design with four replications. Mustard plant densities (0, 7, 14, 21 and 35 plants m-2) were assigned to main plots and canola plant densities (60, 80 and 100 plants m-2) were randomized in sub plots. The results indicated that grain yield, biologic yield, harvest index (HI), silique number sub-branch-1 and grain number silique-1 were significantly affected by interaction between canola and mustard plant densities. Silique number main branch-1, diameter of canopy and first sub-branch height were affected by mustard plant densities. Thousand grain weight, final plant height and sub-branch number plant-1 was not affected by treatments. Furthermore, highest yield loss of 91% was recorded in 35 plants  of mustard in 80 plant m-2 densities of canola. Results also showed no significant difference between canola plant densities (except in pure stand) in any mustard plant densities for grain yield. Therefore, the lower canola plant density (60plants.m-2) could be recommended to decrease seed consumption when mustard is competing with canola in field conditions.

In order to study the effects of planting methods and plant density on sunflower grain yield, a field experiment was conducted in the Dryland Agricultural Research Institute (DARI), Margheh, Iran, in 2000 and 2002 cropping seasons. This experiment was carried out, with two factors, in a split arrangement using Randomized Complete Blocks Design with four replications. Planting methods were assigned to main plots and included planting with planter with 60em row spacing and broadcast + disk harrow (control). Plant densities included, 83000, 55000 and 42000 plant-ha-1 and were randomized in sub-plots. Grain yield, plant height, stem diameter, head diameter, leaf number/plant, plant per square meter (plant.m-2) and 1000 grain weight were measured. Ccombined analysis of variance showed that the effect of planting methods was significant (P<0.05) on grain yield, plant height and leaf numbers. The effect of planting methods on plant.m-2, head diameter and 1000 grain weight was highly significant (P<0.01). Mechanized planting method (average 536kg.ha-1) had the highest grain yield. Plant density had highly significant effect (P<0.01) on head diameter, piant.m-2 and 1000 grain weight Stem diameter was also significantly affected (P<0.05) by plant density. However, the effect of plant density on grain yield was not significant. Decreasing plant density increased head diameter, stem diameter and 1000 grain weight. Planting method x plant density interaction was significant on head diameter. It is concluded that mechanized planting method could be recommended for sunflower crop under dryland conditions in Maragheh region.

Water stress is one of the most important factors limiting growth and production of field crops in arid and semiarid regions. One approach to increase drought tolerance in crop plants is through the symbiotic effect of the arbescular mycorrhizal (AM) fungi. Water deficit stress is typical to semi arid environments and most of the crop plants are affected by drought, during the flowering-grain filling periods. To study the symbiotic effect of the arbescular mycorrhizal (AM) fungi on drought tolerance and some plant characteristics in sunflower, a field experiment was conducted in split plot arrangements using randomized complete blocks with four replications at the Research Field of Tarbiat Moddres University, Tehran, Iran in 2006 cropping season. Three soil available soil moisture contents; 40% (w1), 60% (w2) and 80% (w3) were assigned to main plots and two mycorrhiza species; Glomus mosseae, Glomus hoi and a non- inoculated treatment were randomized in sub- plots. Results showed that the AM fungi species significantly affected all of measured plant traits, except 1000 seed weight, number of total seed m-2, number of filled seed number per m-2 and oil content. However, water stress affected significantly all of measured traits. Water stress x mycorrhiza interaction was negligible on all studied traits except on grain yield and number of unfilled seed per m2 and oil yield. Results indicated that the highest and lowest grain yield and dry matter was obtained in available soil moisture content of 80% and inoculation with G. mosseae and non-inoculated treatments with 1230 and 990 kg.ha-1 of grain yield and 4400 and 3180kg.ha-1 of dry matter, respectively. Results also revealed that different AM fungi species had significantly different effect on seed yield and root colonization under different soil moisture conditions. Seed yield and seed oil content were higher in well-watered with mycorrhiza and without mycorrhiza. Micorrhiza species affected seed yield of sunflower through their effect on seed weight and filled seed number m-2 under well -watered and water stress conditions.

In order to study the effect of genistein and planting date on seed yield and yield components of three annual medic species, an experiment was conducted in split-split plot arrangements using randomized complete block design with four replications in experimental field of Faculty of Agriculture, Tarbiat Modarres University, in 2001 and 2002 cropping seasons. Three annual medic species; Medicago polymorpha cv. Santiago, M. rigidual cv. Rigidula and M. radiate cv. Radiata) adapted to cold and temperate zones were grown in three planting dates (20 February, 29 February and 10 March) with two levels of genistein concentrations (0 and 20 11M). The planting dates, species and genistein concentrations were assigned and randomized to the main plots, sub plots and sub-sub plots, respectively. The results showed that the effect of year on all traits (except number of pod per square meter) was significant (P<0.01). Effect of planting date on all traits (except 1000 seed weight, seed number per pod, seed: pod ratio and 100 pod weight) was also significant (P<0.01). The highest grain yield was harvested from the third planting date (i.e. March 10) with 850kg.ha-1. The interaction of year x planting date was only significant on 1000 seed weight and dry matter. There were significant differences among species for all traits (P<0.01). The interactions of year x species, species x planting date and year x species x planting date were significant on all traits except seed number per pod. Results also showed that genistein effect on all traits was significant except seed: pod ratio and 100 pod weight (P<0.01). Results of this experiment showed that genistein decreased negative effect of environmental temperature on nitrogen fixation, growth and development and seed yield of annual medics. Seed yield of annual medics increased in the second and third planting dates in comparison with the first planting date, due to increase environmental and soil temperatures. At the second and third planting dates, severe variation in air temperature at early vegetative season delayed growth and development of annual medics. Annual medic species showed positive response to genistein application by increasing growth and development and seed yield.

In order to determine the yield stability and to study genotype x environment interaction, 17 alfalfa ecotypes from cold reions in Iran were studied using a randomized complete block design with three replications in 10 agricultural field research stations in 2005 and 2006 growing seasons. Simple and combined analyses of variances were performed. It was revealed that the year x location and ecotype x location x year interactions were significant at the 1% probability level, for both fresh forage and dry fodder yield. For determination of yield stability, different stability parameters were used. Considering dry fodder yield, Shoorkat and Ordoubad ecotypes had the minimum environmental variance and environmental coefficient of variation while ecotypes No.8 and No. 12 had the minimum of Plaisted, Wrikes ecovalance and stability variance. Considering fresh forage yield ecotypes No.6 and No.9 were of higher stability-using environmental variance and environmental coefficient of variation. However, Plaisted, Wricke's ecovalance and stability variance procedures identified ecotypes No.1 0 and No. 13 as the most stable ecotypes. In conclusion, ecotype No.8 for dry fodder yield and ecotype No.1 0 for fresh forage yield were identified as the most stable genotypes-using all of the stability Parameters.

In order to evaluate 26 crop rotation systems, this study was conducted in Research Field of Ramin Agricultural and Natural Resources University in 1999-2003 cropping seasons. Wheat; alfalfa, maize, and canola as main crops and broad-bean, sesame, sudangrass, clover, silage maize and common bean as second crops were planted within traditionally practised crop rotation systems. Studied crops were grouped in 26 different rotation systems using randomized complete blocks design (RCBD) with four replications. Results showed as compared to continuous wheat (5103kg.ha-1), wheat grain yield followed alfalfa and canola increased by 24% and 17%, respectively. However, wheat grain yield followed fallow, maize, sudangrass, silage maize and sesame decreased by 1, 1, 16, 20, 22%, respectively. In comparison of 9 of four-years rotation systems with one period fallow showed that wheat grain yield decreased as the proportion of cereals in crop sequences increased and the proportion of legume crops decreased. Replacement of maize with sudangrass in three-years rotation system decreased wheat grain yield by 22%. Canola was the best previous crop for wheat crop in three-years rotation system as in this system wheat grain yield increased by 33% when compared to sesame. Broad-bean and clover as previous crop for maize, when compared to wheat-maize rotation systems, increased maize grain yield by 19 and 22%, respectively. Comparison of different rotation systems showed that the highest maize grain yield was obtained in fallow-broad bean-maize (12020kg.ha-1) in three years crop rotation system, wheat-maize clovermaize (11290kg.ha-1) in four years crop rotation system, wheat-wheat-maize-clover-maize (11450kg.ha-1) in five years crop roation system and fallow-wheat-wheat-maize-clover-maize (11810kg.ha-1) in six years crop rotation system.