Applied Agricultural Research
Year:2011 | Volume:24 | Issue:3 (92)|Papers Count:14

In order to study the effect of plant density and nitrogen rate on dry matter accumulation and fresh ear yield of sweet corn (Zea mays. var. saccarata), cultivar KSC.403, a field experiment was carried out in research field of Tarbiat Modares University on summer 2005. The experiment was carried out in a split plot design based on randomized complete blocks with four replications. In this research three levels of plant density (60000, 80000 and 100000 plant / ha) as main plot and four levels of nitrogen rate (120, 180, 240 and 300 kg N/ha) as sub plots were investigated. Yield and yield components including grain row number per ear, grain number per row, grain weight and formative characters of ear including ear number per plant, ear length, ear diameter and sucker number were measured. Results showed that sweet corn biomass at the soft dough stage were not influenced by plant density and nitrogen rate. With the increase of plant density, the number of main ear was increased but their weight was decreased. The higher ear length and ear number was obtained by using the lowest plant density and nitrogen rate. In this research with increment of plant density and nitrogen rate, the row number per ear and kernel number per row were decreased. In this respect sweet corn sowned with 60000 plant /ha and 120kg N/ha which produced the longest ear (17.9 cm), the most row number (16.6), the most kernel number per row (34.4) and the highest grain yield 9.33 t/ha) is recommended for the sandy soil in studied Area.

In order to study the effects of post-anthesis heat stress and nitrogen levels on grain yield and yield component of wheat genotypes, two separate field experiments were conducted in delayed and optimum sowing dates under Ahvaz conditions (2006-2007) in Islamic Azad University of Ahvaz. Plants in delayed sowing experienced heat stress from post-anthesis growth stage. Each split-polt experiment had a randomized complete block design with three replications. The application rates of N at three levels (50, 100, and 150 KgNha-1) were in main-plots. Sub-plots were consisted of six bread and durum wheat genotypes. The results indicated that the grain yield reduction in 50 and 100 KgNha-1 compared with 150 KgNha-1 treatment was 41% and 21% under optimum and 44% and 26% under heat stress conditions, respectively. In all genotypes, grain yield and 1000-grain weight (TGW) reduction under post-anthesis heat stress conditions was 42% and 33%, respectively. The highest and the lowest grain yield reduction due to heat stress were observed in Star (39%) and Vee/Nac (27%) cultivars. The Grain yield reduction in low nitrogen levels treatments and post-anthesis heat stress were due to significant reduction in number of grains. m-2 and TGW, respectively. In low nitrogen levels treatments grain number per area was reduced due to reduction in number of fertile florets/spikelets, spikes.m-2, and spikelets. spike-1. Grain growth period average were 23 and 16 days under optimum and post-anthesis heat stress conditions, respectively. Heat stress after anthesis reduced the grain growth rate (12%) and grain growth period (30%) compared with optimum conditions.

Cover crops are considered as a support for sustainable cropping system. Hence, a field study was conducted to examine the effects of cover crops, tillage systems in combination with different nitrogen levels on certain soil properties and sorghum forage yield (cv. KFS3), at Research Farm University of Tehran, Karaj, during 2004-2005 growing season. Factorial-spilt plot arrangement based on randomized complete blocks design with three replications was applied. A combinations of tillage systems including reduced and conventional with nitrogen rates of 0, 75 and 150 kg ha-1 were assigned to whole plots with rye (Secale cereale) and hairy vetch (Vicia villosa) constituted the subplots. Effect of cover crop prior to sorghum planting was significant on soil bulk density, nitrogen and soil pH, but these effects were not significant on soil organic matter. The effect of tillage systems was only significant on soil pH after harvesting forage sorghum. Soil pH was lower in reduced tillage than conventional tillage. Tillage systems had no significant effect on yield of forage sorghum, but cover crops and nitrogen rates treatments significantly affected forage sorghum. The highest forage yields were obtained from rye and vetch cover crops along with 150 kg N ha-1.

In order to investigate the effects of plant growth promoting rhizobacteria (PGRP) on germination and seedling growth of wheat (Triticum estivum L.) under salt stress an experiment was conducted in the physiology laboratory of Sari Agricultural Sciences and Natural Resources University. The experiment was a factorial on the basis of a completely randomized design with three replications. Shanghai cultivar was inoculated with growth promoting rhizobacteria (including Azotobacter coroocoocum, Azospirillum brasilens, Pseudomonas putida, Bacillus lentus) separately, or using different combinations, when subjected to salt stress (including 0, 3 and 6 dS.m-1). Results indicated that different rhizobacteria and different salt stresses had significant effects on all measured traits except for shoot to root ratio. Meanwhile, interaction effects of two treatments caused significant differences except for germination rate and percentage and seedling vigor index. Inoculation of Azotobacter sp. and Azosprillium sp. separately and in combination with the other rhizobactria strains increased germination rate of wheat, compared to the control treatment. Combination of Azotobacter sp. and Azospirillum sp., combination of Azospirillum, sp. Pseudomonas sp. and Bacillus sp. and all rhizobactria significantly improved seedling vigor index. The root and shoot length of wheat was affected by salt stress and decreased with increasing salt stress. However, root length in Azospirillum sp. and Azotobacter sp. together and all rhizobacteria combination were similar to the control treatment. Salt stress at 6 dS.m-1 significantly decreased shoot dry weight. However, this was not the case for the 3 and 6 ds.cm-1 treatments for double inoculation of Azospirillum sp. and Azotobacter sp.

In order to evaluation the allelopathic effects of cool season crops stubble on seedling emergence and early growth of sorghum, soybean and corn, an experiment was conducted in seed library research and greenhouse of College of Agriculture, University of Tehran in 2006. The experiment consisted of cool season crops as main plots, four stubble concentrations (5/3, 7/93, 10/55 and 0 (control) g/kg) and three crops (sorghum, soybean and corn) which were factorially assigned to the main plots. The experiment was arranged as a split plot factorial in a completely randomized block design with three replications. All traits (seedling emergence rate, plant height, shoot dry weight, root dry weight and shoot/ root ratio) were affected by experimental treatments. By an increase in stubble concentration to 20 g/pot germination, percent of the studied crops significantly reduced. Germination of soybean was the most susceptible trait to allelopathic mater. Rye had the highest allelopathic effects on plant height of the studied crops. Root dry weight of soybean was significantly affected compared with that of corn and sorghum. The increase of stubble concentration led to the highest shoot/root ratio in soybean.

This study aimed at assessing of the performance of supervising engineers in increasing productivity wheat in agricultural year 1385-1386 in Kermanshah province from supervising engineers perspective.so This study is using applied, descriptive, correlation methods that were accomplished with square method and by using of questionnaire. The method which is used in this study is multi steps breading sampling for choosing supervising engineers which are under cover of wheat plan in agricultural year 1385-1386 in Kermanshah province. And at the end census was done in this area by 126 supervising engineers which were selected as a sample and the result of the study was analyzed by using SPSS software. the results of correlation between the study variables from supervising engineers point of view show that there is a meaningful relationship between age, using agricultural suggestions in the cultivation period, using agricultural suggestions in the pickup period, the number of operators, the number of contact with the farmers, the number of engineers whom visits dry wheat land, using educational tools, and performance of supervisor engineers in increasing production as dependent variable. The results of plural independent variables on dependent variables based on multiple variables by using regression analysis shows that using agricultural suggestions in the cultivation period and using agricultural suggestions in the pickup period had positive impact on supervising engineers’ performance in increasing production.

In order to study the effects of plant density and irrigation periods on growth indices of Safflower (Carthamus tinctoeius) (Mohally Esfahan) an experiment conducted in Kerman in 2005. completely randomized blocks design in four replicates split plotly. The experimental designe was included irrigation period (I1=7, I2=12, I3=17 every days) and plant density (D1=20, D2=30, D3=40 in each square). The results showed that during every 17 day irrigation period, The plant got to tubudding. Flowering and ripening period sooner than the other irrigation periods. The most leaf growth index (3.21, 3.17 was during). The first irrigation period (every 7 days) and the first plant density (20 plants in each squar metre). Also crop growth rate (CGR) increased (7.9, 784) during the treatment of first irrigation period and the first density. The most ratio growth rate (RGR) was during the first density and the first irrigation period (37 days of planting). As a whole the results showed with increasing irrigation period and plant density in each square metre, leaf erea index and plant growth rate reduced, because of the plant, respiration increasing, internal and outernal competition.

Proving of rhizobia’s other abilities in spite of Nitrogen fixation ability and considering these bacteria as plant growth promoting rhizobacteria (PGPR) researching tasks in this field have incerased. Now, it’s completely proved that we can find such strins among many more strains of each rhizobial group that can also do effective process in plant growth promoting as plant growth hormones production, in addition of their ability in N2 fixation. Such strains can be useful not only for their special host, but also for other plants and strategic products as grains. Soi biotechnology, which follows producation potential of biofertilizers too, which leads improving quality of agricultural products and soil fertility level and life sources contamination preventing, is depend on the use of rhizobia as a good substitute for chemical fertilizers. Several researches were performed about Iranian rhizobia since a decade ago in N2 fixation. Application effect of IAA super strains inoculants on growth index of wheat plant yield was evaluated. The results were indicated that indigenous rhizobia have the potential of Indole auxins production (IAA). Results from the appication of superstrains (IAA+++) inoculants in wheat plant showed that IAA+++ strain had a significant increase in biological yields and N, P and K content. So, the most important stimulation mechanism by rhizobial strains, is production of indole acetic acid (IAA) which results the better root growth, so increase of water and micronurient (N, P and K) uptake by the plant and decrese of the loss of chemical fertilizers.

This research was carried out in Markazi province in order to study the comparative advantage of bean production. Required data were obtained in a survey research by interviewing with 167 bean producers in different regions of the province and filling in the pre-structured questionnaires during 2002-2003 crop year. Gathered data were analyzed using the EXCEL and SPSSWIN softwares. Comparative advantage was calculated using Domestic Resource Cost (DRC), Social Cost Benefit (SCB) and Net Social Profitability (NSP) indicators using two absolute and relative Power Purchasing Parity (PPP) scenarios. In both scenarios, values of the DRC and SCB were calculated less than one and NSP was calculated greater than zero. Results indicated that Markazi province has comparative advantage for bean production.

In order to investigate the effects of silver nano particles on germination and early growth of wheat (Triticum aestivum L.) seedling, an experiment was conducted in the form of completely randomized design with four replications. The factor A included two cultivars of wheat, and seven levels of seed coating including five different concentrations of silver nano particles solution (S), ethanol (E) and a control (sh), were taken as factor B. The results showed that the effects of silver nano particles on germination percent, rate of germination, germination mean time, length of radicle and plumule, dry weight of plumule and seedling, and allometry was significant. Radicle dry weight was not affected by seed coating treatment. Rate of germination, length of radicle and plumule of Verinak cultivar was higher than Chamran cultivar and the dry matter accumulation ability of Chamran was higher than Verinak. Although high concentrations of silver nano particles solution decreased Chamran germination rate, silver nano particles had no effects on this attribute of Verinak cultivar. Radicle and plumule dry matter accumulation was improved under silver nano particles in Verinak cultivar, while this attribute was relatively reduced in Chamran cultivar. The cause of this function could be explained by desirable and undesirable effects of silver nano particles on the length of radicle and plumule in Verinak and Chamran respectively.

In order to survey the efficiency of metribuzin herbicide (sencor %75 wp) in weed control and its influence on wheat cultivars, a field study was conducted in Varamin region. Experiment was carried out in randomized complete block design (RCBD) with 4 replication as factorial arrangement. The experimental factors consist of: wheat cultivar in 3 levels (Shiraz, Pishtaz and M-79-6 line), different amount of metribuzin herbicide in 4 levels (0, 0.5, 0.75 and 1 kg/ha as commercial substance in form of 75 percent wettable powders (wp %75) and time application of herbicide in 2 levels (Pre-emergence and Post-emergence), together with weed infested treatment were compared and evaluated. For results explanation wheat yield (grain & biological), weeds dry matter and their number was measured before and 30 days after herbicide treatment. Results showed that 0.5 Kg/ha dose in pre-emergence time had the most suitable influence on reducing weeds control and least phytotoxicity on wheat cultivars. But due to high phytotoxicity, wheat cultivars and different amount of metribuzin in two time application were not showed any significant difference in wheat yield in weed infested treatments and non-treatments.

A 5×5 half diallel cross set of chickpea (Arman, Hashem, ILC588, ICCV2 and ILC3979) was studied to estimate gene effects and genetic parameters of seven traits. According to diallel variance analysis, only additive genes effects were found significant for plant height, basal pod height and number of primary branches. In addition to the significant additive gene effects, dominant gene effects were significant for 100-seed weight, harvest index, seeds and seed yield per plant. The degree of dominance average (H1/D) 1/2 was lower than one for plant height, basal pod height and harvest index, indicating partial dominance but for 100-seed weight, seeds and seed yield per plant it was higher then one and for number of primary branches it was equal to one that indicating over dominance and complete dominance respectively. The narrow-sense heritability were high for harvest index (67%), 100-seed weight (56%), basal pod height (47%) and plant height (42%) indicating that great genetic gain could be achieved for these traits. Dominant direction was negative and high for all traits with exception of plant height and basal pod height; hence for these traits amplifier alleles were dominance.

Application of doubled haploid method can be used for breeding objectives such ac reduction time of breeding periods. In this research, the effects of photoperiod on embryo production from microspore culture of three rapeseed cultivars; Global, Option and PF7045/91 and plantlet regeneration in embryo-derived from microspores were studied in two separate experiments. In the first experiment, embryo production were analyzed from microspores cultured in NLN-13 medium influenced by photoperiod treatments were; darkness, 16/8 (light/dark) and alternative daily darkness and 16/8 (light/dark) in a factorial experiment based on completely randomized design with two factors in 5 replications. The results showed that there were significant differences between two factors and interaction between them on embryogenesis. The numbers of embryos were increased significantly in Global and PF7045/91 cultivars under darkness condition and embryogenesis were laid in group A for this two cultivar. However, the effect of photoperiod was not significant on embryogenesis in Option cultivar. In the second experiment, the plant regeneration in embryos-derived from microspores was evaluated in a factorial experiment based on completely randomized design with two factors in 10 replications. Cultivar contain Global, Option and PF7045/91 and embryo-derived from microspores under darkness and 16/8 (light/dark) were first and second factor, respectively. The results indicated that only the cultivars had significant differences. The results also indicated PF7045/91 cultivar had the highest plantlet regeneration and was set in group A.

Comparison of uptake and concentration of iron (Fe) in wheat (Triticum aestivum L.) plant using ordinary and nano iron oxides of Folade Mobarake Esfehan wastes in soil was carried out in a factorial completely randomized design with three replications. Ordinary iron oxide (0.02-0.06 mm) and nano iron oxide (25-250 nm) were used at (0, 0.05, 0.1, 0.5, and1.0 % w/w) and two levels of urban solid waste compost coated with sulfur (0 and 2% w/w).Results showed that the uptake and concentrations of Fe in wheat increased significantly by using nano iron oxide more than that of ordinary iron oxide. Also, with increasing both iron oxides levels the uptake and concentrations of Fe in wheat increased significantly. Urban solid waste compost coated with sulfur increased the uptake and concentrations of Fe in wheat significantly. Application of both iron oxides along with urban solid waste compost coated with sulfur resulted in a significant increase in the uptake and concentrations of Fe in wheat. This increase was much more in treatment of nano iron oxide with urban solid waste compost coated with sulfur than that of ordinary iron oxide with urban solid waste compost coated with sulfur.