Iranian Journal of Crop Sciences
Year:2012 | Volume:14 | Issue:1 (53)|Papers Count:10

Quantitative information of nitrogen accumulation and remobilization under varying environmental and growing conditions are limited for wheat (Triticum aestivum L.) cultivars in Golestan province of Iran. This information is used for quantifying nitrogen partitioning between leaves and stems during vegetative stage and the remobilization to the grains during reproductive stage. This experiment was carried out at research farm of the Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran, in 2005-2006 using randomized complete block design with four replications. The experiment was conducted with four spring bread wheat cultivars t (Kohdasht, Shiroudi, Tajan and Zagross) in three planting dates (14 Dec., 20 Jan. and 20 Feb.).Results revealed that N concentration (%) in leaves was 5% up to beginning of grain growth stage, and then declined linearly to 2% at physiological maturity. Stem N% decreased from 2.3% at anthesis to 1.7% in senesced stems at maturity. Results indicated that a positive relationship exists between nitrogen content of grain and whole plant, as each unit increase in the whole plant nitrogen (%) increased grain nitrogen content by 0.89%.This relationship can be used to estimate grain nitrogen content. Nitrogen partitioning in vegetative stage was 58% to stems and 42% to leaves. Those cultivars that had greater remobilization efficiency from stem reserves in reproductive stage also had higher grain nitrogen content. A significant relationship was observed between nitrogen remobilization and nitrogen content of vegetative organs at maturity stage that can be used to predict nitrogen remobilization. It was found that nitrogen remobilization decreased by 25.4% per each unit increase in nitrogen content in vegetative organs. The parameter estimates and functions obtained in this study could be used to simulate N accumulation and remobilization for spring bread wheat cultivars.

To evaluate the effect of foliar application of zinc sulphate on plant characteristics of rapeseed cultivars a field experiment was carried out during 2008-2009 growing season in Shirvan-Chardavol Field Station of Ilam, Iran. The experiment was performed using factorial arrangement in randomized complete blocks design with three replications. The experimental factors included zinc sulphate foliar application (control, foliar application at stem elongation, and flowering stages) and four rapeseed cultivars (Hyola401, Hyola308, Zarfam and Sarigol).Results showed that foliar application significantly affected grain yield, silique.plant-1, grain.silique-1, 1000 grain weight, oil and protein content. Foliar application of zinc sulphate at stem elongation and flowering stages increased grain yield (by 11% and 17%, respectively). Also, oil and protein contents were increased by application of zinc sulphate. The highest oil (35.1%) and protein (27.3%) contents obtained from application of zinc sulphate at flowering stage when compared to control treatment. Cultivars were significantly different for grain yield, yield components, silique length, oil content, protein content and plant height. The highest (4201 kg.ha-1) and lowest (2981 kg.ha-1) grain yield obtained from Zarfam and Sarigol cultivars, respectively. Oil and protein contents were also significantly different in rapeseed cultivars. Zarfam had the highest oil content (34.9%) in comparison to the other cultivars. It is concluded that that zinc sulphate foliar application on Zarfam cultivar at flowering stage resulted in higher seed yield under the climatic conditions of the experimental site.

This study was conducted to determine the relationship between verbalization requirement and phonological development with expression of low-temperature (LT) tolerance in two bread wheat cultivars acclimated under both controlled and field conditions in cold and temperate climates of Iran. Two bread wheat cultivars (MV17 and Shahryar) with different verbalization response and phonological developments were planted under field conditions at Zanjan Agricultural Research Station in cold region and Karaj Agricultural Research Station, Seed and Plant Improvement Institute in temperate zone of Iran in the autumns of 2009. LT tolerance, as measured by LT50, stage of phonological development, as estimated by final leaf number and shoot apex developmental morphology were determined during the autumn and winter seasons. Second set of experiments were conducted under controlled conditions. Norstar (winter wheat) and Azar2 (facultative wheat) cultivars were subjected to cold acclimating temperature (2oC) over a period of 0-89 days and LT tolerance and verbalization fulfillment were measured at various acclimation periods. Results of field experiments showed that winter habit‘cv. MV17’ and facultative ‘cv. Shahryar reached their maximum LT tolerance at LT50=-19oC and LT50=-16oC, respectively, at the point of vernalization fulfillment in Zanjan. While, maximum LT50 of MV17 and Shahryar cultivars were -12 and -8oC in Karaj temperate region, respectively. The level and trends of LT tolerance were different for two cultivars in two different regions. Double ridge was formed very late in plants acclimated in Zanjan cold region. Delay in the vegetative to the reproductive transition in winter wheat cv. MV17 grown in cold region maintained plants for a longer time in the vegetative stage and caused increased level of LT (LT50=-19oC). While plant development to advanced stage reduced the ability of cv. MV17 in Karaj temperate region to acclimate to LT with LT50 of about -16oC. Similar results were observed for LT50 of cv. Shahryar (facultative wheat). with LT50 of about -16oC in Zanjan as compared to LT50 of about -12oC in Karaj supporting the regulatory role of developmental traits in the expression of LT. Results of experiments conducted under controlled conditions showed that cv. Norstar (winter wheat) had a longer verbalization requirement (between 35-42 days) than Azar2 (facultative wheat). Maximum level of LT was achieved about the same time as vernalization fulfillment occurred in both cultivars. It is concluded that both the acclimation conditions of regions and plant development had major influence on controlling of LT in bread wheat cultivars.

To study the effect of integrated planting pattern and plant spacing on competition between maize and redroot pigweed a field experiment was carried out at experimental station of Agricultural College of Ilam University in 2006 growing season. Experimental treatments were arranged as split plot in randomized complete block with three replications. Main plots consisted of planting patterns (single row, rectangular twin rows and zigzag twin rows) and maize plant densities (5.33, 6.66, 8.33, 9.52, 11.11 plant.m-2) were randomized in sub plots. Results indicated that leaf area index, total dry matter accumulation and crop growth rate (CGR) of maize increased in all planting patterns, especially zigzag twin rows planting with 11.11 plant.m-2. However, dry matter accumulation and growth rate decreased in redroot pigweed. In fact, among different maize arrangements, twin rows planting and particularly zigzag twin rows increased grain yield and yield components, on the other hand zigzag twin rows planting arrangement increased competitive ability of maize against redroot pigweed. Zigzag twin rows planting with plant density of 11.11 plant.m-2 produced the maximum grain yield (13632 kg.ha-1), biological yield (21642 kg.ha-1), harvest index (63%), and 1000 kernel weight (440g) as compared to the other treatments. Therefore, the best planting arrangement, based on the finding of this research, is zigzag twin rows planting, i.e. planting density of 11.11 plant.m-2, because of higher grain yield and more effective weed control.

To study the effects of auxin (IAA), abscisic acid (ABA) and cytokinin (CK) hormones on grain yield and its components of rice (Oryza sativa L.) genotypes under low temperature stress conditions, an experiment was conducted during 2008 in phytotron in Agricultural Biotechnology Research Institute of Iran, Karaj, Iran. Three rice genotypes (33: IR72944-1-2-2, 34: IR73688-57-2 as exotic cold-tolerant and Hoveizeh as Iranian cold sensitive genotypes) were foliar-applied with IAA, ABA and CK hormones and treated with two temperatures conditions including; 22/29oC (night/day) and 15/13 oC (night/day) as control and stress temperatures, respectively. Grain weight.hill-1 (g), spikelet.spike-1, fertility (%), maximum tiller number, fertile tiller number were examined in a factorial experiment using completely randomized design (CRD) with four replications.Results showed that there were significant differences among the genotypes. Grain weight.hill-1 of Hoveizeh cultivar was significantly higher in control (26.2 g) than stress (1.4 g) conditions. This trait showed a significant reduction in non-applied treatment as compared with hormonal treatments. IAA, ABA, and CK hormones, under stress conditions, increased grain weight.hill-1 from 1.2 g to 24.1 g, 20.8 g and 30.4 g, respectively. Grain weight.hill-1 under control temperature increased from 26.2 g in non-applied to 40.1 g in CK-applied treatment.There were significant interactions between genotypes and hormonal treatments. Application of hormones prevented the reduction of grain weight.hill-1 under stress temperatures. Grain weight.hill-1 of Hoveizeh cultivar with application of IAA, ABA and CK under stress conditions, showed 94.1%, 93.3% and 95.4% increases, respectively. IAA, ABA and CK applications under stress conditions also increased fertile tillers (%) to 85.5%, 85.5% and 82.3 %, respectively, in comparison to non-applied treatment. CK caused a significant increase in grain weight.hill-1 under stress conditions. It increased the number of spike in Hoveizeh up to 14.4 % under low temperature stress conditions. It is concluded that the amount and balance of hormones are the most important and effective factors in rice plants to tolerate low temperature stress conditions.

Information of inheritance and gene action for silique length is very useful in rapeseed breeding program for development of cultivars with longer silique and incorporating this trait to the new improved cultivars for increasing grain yield. To study the heritability of silique length, an experiment was conducted during 2006-2008 at the University of Agricultural and Natural Resources Sciences of Sari, Iran. Data collected from the three cultivar of rapeseed parents; Foseto, Option 500, Goliath as well as F1, F2 and F3 generations of their crosses. Genetic inheritance of silique length was estimated using generation mean analysis. Results indicated that silique length in rapeseed was mainly controlled by dominant gene effects, and dominant×dominant epistatic was also effective in controlling of silique length. Two RAPD markers (UBC_83, UBC_248) also identified that were associated with silique length, and produced 470bp band by (UBC_83) and 680bp band by (UBC_248). Therefore, these two markers could be used in the breeding programs of rapeseed for identification of genotypes and lines with long siliques to shorten the breeding cycle.

Plastid single-copy gene acetyl- coAcarboxylase (ACCase) is the first agent in the biosynthesis of fatty acids which is suitable for the studying of phylogenetic relationships, evolutionary and systematic of grasses. Single and low copy genes are less likely subject to concerted evolution, thus making themselves ideal tools for studying the origin and evolution of polyploid taxa. In this study, phylogenetic relationship of seven species and subspecies of (Hordeum) of Iran including (Hordeum murinum L.), (Hordeum marinum Hudson), (Hordeum brevisubulatumTrinus Link), (Hordeum spontaneum K. Koch), (Hordeum bulbosom L.), (Hordeum vulgare convar.distichon L.), (Hordeum vulgare convar. hexastichon L.), were investigated using gene-specific primers acetyl- CoAcarboxylase (ACC1) and then compared their sequences with the sequences of species of Leymus and Elymusgenera. A great diversity was observed in the wild barley from Iran. Phylogenetic tree grouped all samples in two main groups. The first group consisted of all accessions of Leymus and Elymus genera as well as two accessions of Hordeum. While the second group consisted of all Iranian species/subspecies of Hordeum along with Hordeum vulgare L. with unknown origin. Since ACC1 gene is a valuable source for phylogenetic analysis in the Triticeae tribe, this research investigated the genomic and evolutionary relationships of the Hordeum, Leymus and Elymus genera and dtermined reasonable and important Taxonomy relationships among Hordeum species from Iran.