جستجوی مقالات مرتبط با کلیدواژه « development » در نشریات گروه « زراعت »

The increasing demand for diverse fodder plants, along with the challenges of its production such as the pressure on pastures, has led to increased attention to strategies for maximizing the production of these plants per unit area. Millets are a good choice for crop rotation and production patterns in different regions due to their high diversity, high adaptability, high dry matter production, and high nutritional value. However, the appropriate planting date and the compatibility of the growth stages of millet with environmental conditions are essential for maximizing production. This study was conducted to evaluate the effect of different planting dates on the growth indicators of proso millet and how its growth stages are compatible with environmental conditions.

To achieve the objectives of the research, a two-year field experiment was conducted in 2016-2017 and 2017-2018 at the research farm of the Faculty of Agricultural Sciences of the University of Guilan. A randomized complete block design with four replications and four planting dates was used (May 29, June 27, July 29, and August 29 in the first year; and June 4, July 7, August 5, and September 6 in the second year). Plant growth indices, plant response, and the compatibility of plant growth stages with environmental conditions were investigated through repeated sampling, measurement of plant leaf area and dry matter of different plant parts, and recording of phenological stages.

The results of this experiment showed that the interaction between year, planting date, and sampling time had a significant effect on the accumulation of dry matter and the growth indicators studied, such as leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR), net absorption rate (NAR), leaf area ratio (LAR), and leaf weight ratio (LWR). In the first cropping year, the highest total dry matter accumulation of proso millet, with an average of 1030.8 grams per square meter, was obtained by planting it on June 27. This was due to the maximum LAI (5.14 cm²·m²) and crop growth rate (35.5 g·m²·day⁻¹) obtained in the second planting time, which led to a significant increase in dry matter compared to the other three planting dates. However, in the second year of the experiment, planting proso millet on June 4 resulted in a significant increase in LAI (3.69 cm²·m²), CGR (25.99 g·m²·day⁻¹), and NAR (18.13 g per square meter of leaf area per day) compared to the other three planting dates. As a result of the aforementioned growth indicators, the total dry matter accumulation of proso millet was 734.66 grams per square meter, which showed a significant increase compared to the other three planting dates.

Overall, the results of this experiment suggest that the optimal planting date for proso millet in Rasht is between June 4 and June 27. Planting during this period resulted in the highest accumulation of dry matter and the most favorable growth indices. The findings of this study can be used to improve the cultivation practices of proso millet in Rasht and other similar regions.

To investigate the effects of foliar application of salicylic acid and selenium on agronomic characteristics and grain protein content of dry land wheat, Sardari variety, a experiment factorial was conducted in randomized complete block design with three replications. Experimental factors were foliar application of 1 mM salicylic acid at of booting, flowering and dough developmental stages along with control (spraying with water), and foliar application of 18 g/ha selenium at stem elongation, heading (spike emergence) and milk developmental stages along with control (spraying with water). The results showed that both salicylic acid and selenium improved the studied traits, so that foliar application of salicylic acid at flowering stage had the highest biological yield (9202 kg/ha) and grain protein (11.3%), and foliar application of selenium at heading and stem elongation stages had the highest biological yield, spike length, grain protein content and number of tillers. Also, combined application of salicylic acid and selenium compared to their separate application had better results on plant height, yield and yield components of wheat, so that the highest grain yield, number of spikes and number of grains per spike were observed in foliar application of salicylic acid-selenium at flowering-stem elongation and booting-stem elongation stages. Therefore, the results of this study showed that foliar application of salicylic acid at booting and flowering stages along with foliar application of selenium at stem elongation and heading stages were the best treatments in this experiment and it is recommended to improve the yield and yield components of dry land wheat.

In this research, the effect of concentration and time of seed priming with salicylic acid on germination and early growth and it’s application methods under salinity stress conditions on phenology characteristics of barley, variety Reyhan, was studied in two separate experiments. The effect of concentration (in five levels, control, 0.5, 0.75, 1.0 and 1.5 mM) and time (in three levels, 6, 12 and 24 h) of seed priming by salicylic acid (SA) in the first experiment and different application methods of SA (no application, priming and spraying at the stages of establishment, double ridges and anthesis) under different salinity conditions (no stress and salinity of 6 and 12 dS.m-1)in the second experiment was evaluated. Both experiments were conducted as completely randomized design with four replications at College of Agriculture, Shiraz University, Iran, in 2014. The results of the first experiment showed that SA-priming with 1.5 mM for 12 h had the highest positive effect on germination and early growth, which was selected for the second experiment. The results of the second experiment showed that salinity stress of 6 dS.m-1 reduced the planting to anthesis period as well as planting to physiological ripening and 12 dS.m-1salinity stress also reduced the planting to booting, planting to anthesis and planting to physiological ripeningperiods. Seed priming with SA prolonged the growth periods, whereas the delay in SA application decreased its positive effect. Foliar application at establishment increased planting to booting, planting to anthesis as well as planting to physiological ripening periods,however foliar application at anthesis had no significant effect on phenology of barley plants. In total, seed priming or foliar application at establishment at early growth stages ameliorated the acceleration of the developmental stages due to salinity stress and early application of SA was found to be more important with increasing salinity stress.

In order to study the seed quality indicators of hybrid maize seed at development and maturity stages and planning harvest time, an experiment was conducted in a complete randomized design, with three replications and five sowing dates (T1 = 22 April, T2 = 6 May, T3 = 21 May, T4 = 12 June and T5 = 29 June) in Karaj, Iran. Phenology and morphology related traits were evaluated during plant and seed growth. After pollination, Sampling from ears was done in weekly scale from female rows (B73 Inbred line). The harvested seeds were dried in open air condition, and then laboratory tests were done. Depends on the sowing date and temperature, seed filling rate (SFR) and periods (SFD) were significantly different. Physiological maturity or maximum normal seeding occurred around 47-68 days after flowering (DAF), when the seed moisture varied in a range of 40-54 % and mass maturity (maximum seed weight) occurred at 47-86 DAF, when the seed moisture ranges about 40-43%. But black layer in seed formed when the seed moisture was about 32-35%. So, maximum seed quality occurred earlier to mass maturity. While the black layer formation happened as the final stage of development. The more the delay in sowing dates, the higher the seed moisture for occurring mass and physiological maturity. Depends on the sowing date and appropriate drying, harvesting the seed at higher level of moisture was possible. It is more likely that seed moisture prepare a more suitable indicator for detecting the changes trend in mass and physiological maturity, in compared with DAF and GDD.

Effects of drought stress and chemical treatments was studied on growth and developmental traits of four barley cultivars using a split- split plot design (RCBD) in Agricultural Research Farm, Kerman University in 2013-14. Main plots consisted of irrigation (control and drought stress after flowering), sub-plots consisted of four barley cultivars (ʻNosratʼ, ʻAfsalʼ, ʻYousofʼ and ʻUH12 lineʼ) and sub-sub plot consisted of control, salicylic acid (0.5 mM) as seed soaking, foliar spray at anthesis and seed soaking foliar spray) and also foliar spray with selenium (40 mg/l using sodium selenate). Drought stress significantly decreased chlorophyll index (10 percent), thousand grain weight (19 percent), grain yield (20 percent), biological yield (11 percent) and harvest index (12 Percent). On the contrary, salicylic acid increased plant height, length of spike and awn, chlorophyll index, thousand grain weight, grain yield, biological yield and harvest index. Foliar spray of plants with sodium selenate increased selenium contents of grains in all cultivars. However, it could be concluded that salicylic acid improved plant performance under normal and drought conditions and selenate application enriched barley grains, and therefore those treatments are commercially recommended.

Saffron (Crocus sativus L.), a native plant from Iran and especially of Khorasan region, has a specific place for people's diet. According to several studies about effects of saffron and because there are no specific studies on the effects of saffron aqueos extract on the development of Drosophila melanogaster as an animal model, this subject evaluated in conversion of larvae to pupa and pupa to mature of fruit flies. 5 pairs of 3-day-old wild D. melanogaster were transferred to every culture plate containing different concentrations of saffron aqueos extract in order to intercross and oviposition and were brought out after 8 hrs. The percent of larvae to pupa transitionand pupa to mature conversion, were evaluated in all concentrations. The obtained data were evaluated statistically using SAS software and the mean of data were compared using Tukey test with minimum significance level of p<0.05. In low volume of saffron, resulted in the increased conversion of larvae to pupa and pupa to mature in comparison with the control group. But, presence of high volumes of saffron on the medium leaded to significant decrease of percentage of conversion of larvae to pupa, pupa to mature. With regard to the obtained data, the effects of saffron on the genesis of D. elanogaster depends on dose proportionately. It means that saffron has some effects on the percentage of conversion of larvae to pupa, pupa to mature in low volumes and increased consuming concentrations of saffron may have inverse effects on that.

This study was conducted to determine the relationship between vernalization requirement and phenological 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 (MV17and Shahryar) with different vernalization response and phenological 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 phenological 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 (2°C) over a period of 0-89 days and LT tolerance and vernalization 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 LT5 = -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 vernalization 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.

Plants are exposed to environmental stresses. Water and nitrogen availability are two major factors for crop production under different conditions. In order to determine the effects of water deficit and different nitrogen rates on growth and developmental stages, yield and yield components of corn, two field experiments were conducted using a randomized complete block design in 2001 growing seasons. Two corn hybrids (KSC 108 and KSC 301) were used under water and nitrogen stresses at vegetative and reproductive growth stages in two locations (Hamedan and Karaj). The result indicated that phenological stages delayed under water and nitrogen stresses in different treatments. Leaf area index decreased as availability of water and nitrogen decreased. Significant differences were observed between two hybrids for biological yield, grain yield and yield components. The lowest biomass and grain yield were produced in water stressed plants at both vegetative and reproductive stages. The different rates of nitrogen utilization shown significant effect on grain yield. Water deficit at vegetative and reproductive growth stages decreased the grain yield by 15% and 20%, respectively in comparison with controls. Relative water content reduced by 15-18% under water and nitrogen stresses. There were no significant differences in harvest index, but stress index (SI) was different between stressed treatments. The maximum stress index (SI) belonged to KSC 301 under water stress at the vegetative and reproductive growth stages.