Journal of Plant Production Research
Year:2011 | Volume:18 | Issue:1|Papers Count:11

In order to determine radiation use efficiency and phenological and physiological characteristics of three maize hybrids on seven plant densities, an experiment was conducted during 2006 growing season in Mashhad, Iran. Three maize hybrids including late-rippening maize (704), medium-rippening (504) and early-rippening maize (260) and seven plant densities including D1=3, D2=5, D3=7, D4=9, D5=11, D6=13 and D7=15 plants m2 were compared in a strip plots design with three replications. There was significant difference on plant growth period and there were difference effects on dry matter, leaf area index, crop growth rate, net assimilation rate, and leaf area duration. Optimum indices were obtained in third plant density (D3) for late-rippening hybrid (704), in fourth plant density (D4) for medium-rippening hybrid (504) and in fifth plant density for early-rippening hybrid (260). When increasing plant density more than optimum rang of density, the time interval between pollination and silking increased while plant growth period decreased. When the plant density increased, leaf area index, dry matter and light use efficiency were increase too.

Water and temperature are determinant factors for seed germination. Both factors can, separately or jointly, affect the germination percentage and germination rate. The effect of temperature on germination and water potential on germination can often be described by the thermal time and hydrotime models, respectively. Additionally, the thermal time model and the hydrotime model have been combined into a hydrothermal time model to describe the combined effect of water and temperature on germination. The objective of this study was investigation interaction effect of five levels of temperature (7, 10, 15, 20 and 25 °C) and five drought stress levels (0, -0.2, -0.4, -0.6 and -0.8 MPa, by PEG-6000) on the germination of the Velvetleaf plant (Abutilion thephrasti med.) and two soybean cultivars (DPX and Williams) seeds. This experiment was done in during 2010 in the seed research laboratory of Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran. Results indicated that the base temperature and the thermal time to 50% of germination (°Cday-1) in each three plants increase significantly with decrease in water potential. Also, in low water potentials thermal time in the Velvetleaf was lower than two soybean cultivars. The base water potential (from -0.9 to -0.6 MPa) and hydrotime to 50% of germination (from 1.4 to 10 MPaday-1) in each three plants increase significantly with decrease in temperature from 25 to 7 °C. Generally, in low temperatures of amount hydrotime in the Velvetleaf was lower than two soybean cultivars. After fitted the hydrothermal time model the base temperature, the hydrothermal time constant and the base water potential for germination of the Velvetleaf, DPX and Williams were 3.9, 4.3 and 5.2 °C, 26.7, 26.5 and 27.3 MPa°Cday-1 and -0.9 MPa for each three plants, respectively. Results this study indicated that Velvetleaf plant in conditions of drought stress and temperatures similar had higher competition power than soybean cultivars studied.

In sustainable agriculture, using of resistant plants is one of the best methods for integrated pest management. Resistance of 140 rice promising lines against striped stem borer was evaluated in two planting date in the field under natural infections in Sari Agricultural Science and Natural Resources University during 2008-2009. This study carried out as a factorial experiment in Randomized complete block design with three replications. The results showed that lines of 131 (Noksiah×Fajr) with 94.2% and 27 (Sang tarom×Deylamani) with 91.4% had the highest percentage of infection and lines 2 (Tarom×Deylamani) and 70 (IR58025A×IR-19R/Neda) had the lowest percentage of infection against the striped stem borer. Therefore, these lines identified as lines of susceptible and relatively resistant, respectively. In evaluation of white head in lines to striped stem borer, the results showed that 21.42% of total lines were susceptible and 11.63% were resistant. Also, percentage of infection (9.62%) and white head (14.17%) in second planting date (mid June) were higher than first planting date. Coefficients of correlation for morphological traits showed that plant height (r=0.197) and tiller number (r=-0.101) had effect on percentage of infection and tiller number (r=-0.25) on percentage of white head. Also, it represented correlation between stem diameter and tiller number. Increasing of tiller number causing decreasing of stem diameter make effective resistance.

In order to evaluate plant density and cultivar effects on rate and process of grain filling, yield and yield components of three dry bean cultivars a factorial experiment (using R.C.B. design) was conducted in 1386 at agricultural and natural research center of East Azarbaijan (Tabriz). Three cultivars (Khomeyn, G-14088 and 11816) were planted at four densities (14, 20, 30 and 60 plants/m2) in three replications. A two-part linear model was used to quantifying the grain filling parameters. Interaction effect of cultivar and plant density affected grain filling rate (GFR), mass maturity (MM), maximum grain weight (MGW) and effective filling period (EFP) significantly. Highest amount of GFR, MM, MGW and EFP observed at Khomeyn cultivar in lowest density (14 plants/m2). These four parameters decreased in Khomeyn and G-14088 cultivars with increasing in plant density significantly. Between cultivars and plant densities treatments of dry been was significant difference in all of yield and yield components. But interaction effect of cultivar and plant density affected only number of day to maturity, number of pod in plant, 100 kernel weight, grain yield and percent of grain protein parameters. All of these parameters (except grain yield) decreased with increasing in plant density. But increasing of plant density and number of pod in square meter compensated it and increased grain yield with increasing all of parameters in square meter. Grain yield is important than other parameters. Khomeyn cultivar had maximum amount GFR, MGW, EFP, number of grain, 100 K.W, HI and grain yield. Therefore Khomeyn cultivar and 30 plants/m2 are best cultivar and plant density in region respectively.

In this research seed of twelve population of Iranian onion were gathered from different part of country (Horand Ahar, Germez Rey, Goligesa Zanjan, Germez Azarshahr, Sefid Kashan, Zard Neishabur, Sefid Gom, Dorche Esfahan, Sefid Neishabur, Germez Neishabur, Sefid Fathabad, Es hag abad Neishabur). The experiment was factorial based on a randomized complete block design (RCBD) was conducted in Agricultural Reasearch and Natural Resources Center of East Azarbayjan with three replications. Analysis of variance showed different between cultivars in bulb pungency, dry matter, total yield, percent of fusi form bulbs, bulb diameter, bulb neck diameter and number of outer dry skin. Some of traits such as bulb neck diameter, number of outer dry skin are important in bulb storage. Variation of these traits according to vast diversity of Iranian onion population is important and helpful for culture and storage.

Screening is an important subject for breeding programs of resistant varieties of lentil. In recent years many developments were carried out in identification of resistant sources of germplasm of leguminous against soil-borne causes. Fusarium oxysporum f.sp. lentis is one of the important disease of lentil in the world and Iran. In this study, reactions of 30 lentil genotypes evaluated to find resistant sources against 10 isolates of Fusarium wilt, isolated from different fields of North and Razavi Khorasan provinces, in greenhouse condition. This genotypes inoculated using spore suspension and cultured in sterile soil. The disease severity was scored on a system of 1 to 9 of Bayaa. Results showed most percent of high resistance of genotypes related to HO3F3 (Razavi Khorasan) and most percent of resistance is RA1F1 (North Khorasan) in seedling stage. But, no genotypes caused resistance against isolates of Fusarium in reproductive stage. Of course, HO3F3 showed the least of aggressive of all isolates of Fusarium both in seedling and reproductive stage.

This study was conducted to investigate the effects of in vitro and regeneration of lily (Lilium longiflorum) bulb scale by different plant growth regulators in B5 medium in a completely randomized design with factorial arrangement and 4 replications. Treatments consisted of indole-3-acetic acid (IAA) and 2,4-D in B5 medium in four concentrations (0, 0.5, 1, 2 mg/lit) and these were combined to medium. Evaluation of results indicated that with increasing of IAA concentration, number of bulblets increased significantly but between using of various IAA concentrations and rooting parameters and callus formation, no significant difference was observed. With increasing of 2,4-D concentration to 2 ppm, callus fresh weight was enhanced, whereas with increasing of 2,4-D concentration, organogenesis suppressed completely. According to the results, about 100-150 plantlet were achieved per adult bulb of lily.

Priformospora indica or Piri is an endophytic mycorrhiza in which its growth stimulation effect on host plant by increasing adventitious roots has been reported. The effect of Piri on medicinal plant and secondary metabolite accumulation has been less studied. Present study was performed in growth chamber conditions (light density 2500 lux, 16 day length and 25 °C) as a completely randomized design with contaminated and non-contaminated plants and four replications. The number of adventitious roots of contaminated plants strongly was higher than that of non contaminated plants. The results also showed that the leaves width of contaminated plants was significantly higher than that of non-contaminated plants. Although the content of Cafeic acid of contaminated plants was higher than that of non-contaminated, but the difference was not significant. According the short period of experiment, it seems that the formation of most of polyphenolic compounds did not complete or the amount was not detectable. Thus repeating present study in field conditions could help the better understanding the relationship of fungus and plant, especially on secondary metabolite accumulation.