جستجوی مقالات مرتبط با کلیدواژه "منبع" در نشریات گروه "زراعت"

Silicon is increasingly recognized as a beneficial element for improving plant growth by enhancing physiological, biochemical, and molecular responses. It plays a role in various plant processes like osmosis, metabolism, stomatal physiology, and phytohormone relationships. Some researchers believe that silicon, as a signaling molecule, reduces damage caused by reactive oxygen species and ionic leakage by increasing the plant's antioxidant defense capacity. silicon plays a significant role in increasing the accumulation of photosynthetic materials in seeds; researchers attribute this increase to the flow of assimilates towards the seed, reduced source limitation, enhanced sink capacity, and improved remobilization of photosynthetic materials. The results indicate that silicon can affect the production and allocation of dry matter and the relationship between source strength and sink size. The consumption of silicon leads to favorable interactions with fertilizer elements such as potassium, thereby enhancing agronomic traits and improving the efficiency of this element to increase yield. Potassium plays a crucial role in osmotic control, enzyme activity, regulating cell pH, maintaining the balance between anions and cations within cells, controlling evaporation and transpiration through stomatal regulation, and aiding in the transport of metabolic materials from photosynthetic activities, ultimately improving yield by increasing leaf area and chlorophyll content. It has been shown that the application of silicon improves biomass, seed yield, and tiller number in several crops. Bitter vetch is a forage plant from the legume family and is native to regions in West and Southwest Asia, cultivated in various countries, including Iran. Bitter vetch is ecologically adaptable to drought and has always been of interest due to its high nutritional value, short growing period, and ability to fix soil nitrogen. The research aims to investigate the effect of silicon as a signaling molecule in nutrient remobilization in bitter vetch to enhance yield.

In order to investigate the effect of potassium silicate levels (control (distill water), 2/1000, 3/1000, 4/1000 and 5/1000) on bitter vetch plant yield, an experiment was conducted in the form of a randomized complete block design with three replications at the Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. In this study, local seeds from Lorestan province were used. The seeds were manually planted at a depth of two centimeters in the soil in the first half of February 2022. The application of potassium silicate was carried out in two stages as foliar spraying. The first stage took place at the time of pod formation and 10 days after first application. At the end of the growth season, morphological traits including plant height, lowest pod hight, number of secondary branches in five plants, 1000- grain weight and yield traits were were measured and recorded. Statistical analysis was performed using the LSD method.

The application of potassium silicate significantly affected plant height, leaf canopy height, number of secondary branches, seed weight, seed yield, biomass, and harvest index. Silicon plays a role in strengthening the cell walls of stems and leaves, enhancing their physical strength, which can improve plant growth and light absorption by leaves, thereby stimulating plant growth. The results showed that the highest grain yield and biological yield in the foliar spraying treatment were 5/1000 and 4/1000 potassium silicate, which increased by 28 and 44%, respectively, compared to the control. In addition, the highest plant height, the number of branches and the weight of 1000- grain weight were observed in treatment of 5/1000 potassium silicate. The results showed that grain yield has a positive and significant correlation with the number of sub-branches (r = 0.51**), 1000- grain weight (r = 0.65**) and biological yield (r = 0.46**), respectively. In the present experiment, the positive and significant correlation of seed yield with the weight of 1000- grain weight and biomass shows that the process of transferring and distributing photosynthetic products to the reservoir is directly related to the source. The application of potassium silicate had a positive impact on various physiological processes, leading to increased biomass production and ultimately enhancing seed yield.

The application of potassium silicate significantly increased seed yield and had positive effects on various yield components of bitter vetch plants. Silicon application during the formation of sheath and sheath development enhances the translocation of photosynthetic materials to reproductive organs, ultimately improving plant performance.

Wheat stem reserves can be an important contributor to grain particularly under decrease in the source strength through defoliation. The aim of this research was to study ability remobilization as important contribution on yield stability under drought conditions and to investigate their intrinsic compensatory mechanism in the wheat cultivars with different degrees of resource limitations under source limited conditions. To test this hypothesis، two separate field experiments were carried out at research field of university college of Agriculture and Natural Resources، university of Tehran (located in Karaj) during 2010-2011 growing seasons. First experiment was carried out in a split plot design based on RCBD that included 36 wheat cultivars and different levels of defoliation (non-defoliated control (ND)، removal of all leaves (FD)، removal of all leaves except the flag leaf (PD)) and the Second experiment as a randomized complete block design that included 36 wheat cultivars and chlorophyll desiccation. The plants were defoliated and desiccation in 15 day after flowering growth stage. The result showed that removal of all leaves except the flag leaf (PD) and all leaves (FD) caused reduction of grain weight by 8% and 22%، respectively. Also highest grain yield were obtained of Fongh cultivar in PD and FD treatment. Generally cultivars with higher accumulation were less affected by defoliation treatments. Wide ranges of remobilization were detected between cultivars and highest remobilization was obtained of Crossed Shahi cultivar. Contribution of stem reserves to grain yield was by 36%.

Studies manipulating the source-sink relationships during post anthesis in wheat have shown inconsistent results، concluding that wheat yield could be either sinkor source-limited. The aim of this study was to determine source limitation degree of 36 Iranian wheat cultivars andto investigate their intrinsic compensatory mechanism in response to source size reduction. A split plot design based onrandomized complete block designwas carried out with 3 replications. Treatment included 36 wheat cultivars and different levels of defoliation (non-defoliated control(ND)، removal of all leaves (FD)، removal of all leaves except the flag leaf (PD)). Defoliation was carried out at flowering stage. A wide range of responses to defoliation treatments observed among the cultivars، suggesting a high variation in sink or source limitation among the cultivar while them were cultivars with no response sever leaf defoliation (FD) same cultivars different even by mild leaf defoliation (PD)، thatimplying to possible various compensatory mechanism in cultivars.

To study the effect of different planting dates and source-sink limitations on grain yield and its components in three rapeseed cultivars, a field experiment was conducted using split-factorial arrangements in randomized complete block design with three replications at Bayekola Research Station, Sari, Iran, in 2006 and 2007 cropping seasons. Planting dates; 22 October and 01 November were assigned to main plots and three rapeseedcultivars: Hayola 401, RGS 003 and Sarigol and source-sink limitations at five levels: removing 1/3 of leaves from lower, middle and upper parts of plant, removing 1/3 of flowers and control in factorial arrangement were randomized in sub-plots. Results showed that rapeseed cultivars had very significant (P<0.01) differences for allmeasured traits, except for grain number.silique-1 (P<0.05). Planting date had significant effect on plant height, grain yield, silique number.plant-1 and silique length. The first sowing date was more suitable than the second date for growing rapeseed cultivars. Hayola 401 and RGS 003 had the highest grain yield (2911 and 2808 kg.ha-1) in the second cropping season, and the highest grain yield (2988 kg.ha-1) at the first planting date was related to Hayola 401. The lowest grain yield was obtained from RGS 003 (974 kg.ha-1) in 2006 cropping season and, the second planting date (1556 kg.ha-1). All treatments - significantly (P<0.01) affected the silique number.plant-1. Furthermore, all traits except silique number.plant-1 (248.08 siliques in 2007) and 1000 grain weight (4.08 g in 2007), had greater scores in 2007 in comparison with the 2006 cropping season. It seems that source limitation might not be determining factor for mentioned rapeseed cultivars, because of better yield in cutting of one third lower leaves compared to control.

In order to study the effect of different nitrogen fertilizer rates and source-sink limitation treatments on yield and yield component of contrast rice (Oryza sativa L.) cultivars, a field experiment was carried out in the Rice Research Institute of Iran-Deputy of Mazandaran (Amol) during 2006. A split split experiment in the basis of randomized complete block design with 3 replications and 3 factors were used in which fertilizer rates in 3 levels (including 100, 150 and 200 kg/ha from urea source) as main plots, rice cultivars in 3 levels (including Tarom, Shafagh and Bahar1 hybrid) as sub plots and source-sink limitation treatments in 4 levels (including cutting of flag leaf, cutting of leaves except flag leaf, cutting of 1/3 the end of panicle and control or without limitation) as sub sub plots were the treatments. Results showed that nitrogen rates had not significant effects on the studied traits expect on panicle length but cultivar and source-sink limitations significantly affect all studied traits such as grain number per panicle, 1000 grain weight, panicle length, panicle fertility percentage and unfilled grain number. Bahar1 hybrid had the highest grain yield, biomass, total grain number, unfilled grain and filled grain among cultivars. Among different source-sink limitation treatments, the lowest grain yield were observed when all leaves except flag leaf removed from plant probably because of induced source limitation. Also interaction effect of nitrogen fertilizer in source-sink limitation treatments showed that the highest yield was observed in 200 kg.ha-1 and control treatment. Among the mentioned traits, biomass (r=0.76**), harvest index (r=0.50**) had the highest positive and significant correlation with grain yield. In general, modern cultivars (Shafagh and Bahar1) had higher sink capacity than Tarom cultivar (traditional) that considered as a sink-limited cultivar.

In order to determine, source of grain yield limitation under different enviromental conditions, as well as indentifying the rate of restrication caused by terminal heat stress on development and growth of wheat, this research was conducted with twenty wheat genotypes using Randomized Complete Block Design (RCBD) with three replications, in two separate experiments in two years(1998-2000). The experiments were sown in late of december and january to stimulate favoarable and unfavourable conditions, respectively. Five to seven days after anthesis flag leaf and spikelets from one side of spike were removed to stimulate, sink and source limitation respectively. Aftert harvest, source and sink restrication percentage were calculated according to the mean of remaining grains in treated spike and control (without removal of flag leaf and spikelets). Results indicated that all genotypes had not sink restrication and the contribution of flag leaf to grain dry weight was 12%. However, some genotypes showed source restrication. This restrication was estimated from 0 to 34% (mean: 12.6%) and 5.7 – 41.2% (mean:17.2%) for favourable and unfavourable conditions, respectively. Therfore, source restrication caused by exposure to terminal heat stress was greater by 6%. Likewise, results indicated that source restrication was higher in genotypes with large grain size. Grain weight had not significant effect in the determination of final yield. Reduction in grain yield must be sought in other yield components, such as grain number per spike and spikes number per sqaure meter.