Journal of Plant Production Research
Year:2009 | Volume:16 | Issue:4|Papers Count:13

Selection of an appropriate model is important for quantifying response of germination rate to temperature and determination of cardinal temperatures. This study was done to evaluate different nonlinear regression models to describe response of germination rate to temperature in medicinal pumpkin, borago and black cumin. The regression models were dent-like, segmented, beta, curvilinear, quadratic and cubic. Root mean square of error, coefficient of determination, correlation coefficient and regression of predicted values versus observed ones were used to find the appropriate model (s). Dent-like and beta models were superior compared to other models in medicinal pumkin and black cumin. In borago, dent-like, beta and curvilinear models were superior. It was concluded that these models can be used to quantify response of medicinal pumpkin, borago and black cumin germination to temperature and to obtain cardinal temperature of germination. These parameters are required to predict medicinal pumpkin, borago and black cumin germination and emergence.

Harvesting of sour cherries is very difficult task which is done either by machine or hand. In order to facilitate fruits harvesting ethephone with different densities is used. In this research work Iranian produced ethephone with density of 1.18 g/cm3 and England produced ethephone with density of 1.45 g/cm3 was utilized with different concentration (0, 150, 225 and 300) in a 2×4 factorial experiment for types and concentrations of ethephone on fruit detachment force from pedicle, fruit abscission percentage and some of fruits quantitative as well as qualitative properties. Type of ethephone hormone only has significantly affected properties such as fruits weight, fruit detachment force from pedicle, abscission fruit percentage and soluble solid content (°Brix) while did not have significant effect on average 1000 pit weight flesh/pit ratio, fruit diameter, fruit firmness, pH, titratable acidity, suger/acid ratio and color characteristics. The increasing concentration of ethephon decreased fruit detachment force from pedicle, firmness and titrateable acidity and increased brix°, fruit weight and fruit abscission percentage.

Recognizing of genetic diversity and genetic potential of each plant species is necessary and essential before any works on breeding program. Genetic diversity among five populations of walnut (Juglans regia L.) was studied using 11 SSR markers. The marker system produced 77 alleles in a range size of 176-275 bps. The minimum (2) and maximum (11) numbers of alleles were related to genetic locus of WGA027 and WGA202, respectively. The mean number of alleles for 11 loci was 7 alleles. The number of effective alleles was between 1.57 and 5.32. The mean number of effective alleles for each locus was 3.77. In general, increasing trend of the allele’s number was in relation with Shannon information index. This was observed for Galikesh and Kalaleh populations. These populations had more diversity within each of them. Reversely, Kordkouy population had the lowest Shannon index and the lowest diversity among the selective populations. The highest genetic distance was between Kordkouy and Afratakhteh (0.30). The lowest distance was related to Galikesh and Cheshmah-jouzi (0.12). Classification of populations based on molecular data did not match with their geographical situations.

The effects of an Azotobacter Chrococum isolate (strain Ag11) and vermicompost and their combined effects on a rain-fed winter wheat (var. Zagros) nutrient uptake and growth and soil water content were investigated with a farm trial.  The dry matter yield was determined in 5 occasions. Gravimetric soil water content, soil microbial respiration and the number of Azotobacter were determined at same occasions. Grain yield and yield components were measured at harvest. Soil nitrate and ammonium, potassium, phosphorous, calcium, magnesium, iron, zinc, copper, manganese and cadmium were determined before heading and at harvest. Total nitrogen, potassium, phosphorous, calcium, magnesium, iron, zinc, copper and manganese were also determined for plant tissues before heading and at harvest and also for a representative vermicompost sample. Treatments with Azotobacter inoculation improved dry matter yield before heading, spikes per square meter, grain yield and straw. Azotbacter increased root density and potassium availability in rhizosphere. Vermicompost also increased grain yield. In addition to a low correlation with potassium uptake a high quantity of potassium is extracted by ammonium acetate relative to preset sufficiency levels which are misleading. Maximum correlation with potassium uptake and yield were obtained by extraction with sodium tetra phenyl boron. Soil water contents were not affected by any treatment.

In order to determine the effect of different tillage methods on grain yield and yield components of two wheat cultivars an experiment was conducted in Sanandaj in during 2005 and 2006-2007. Experiment was carried out in a split plot design based on RCBD with four replications. The three methods of tillage, including moldboard plow, chisel plow and no tillage were arranged as main plots, and two cultivars (Sardari and Azar 2) as the subplot. Also, the effect of different tillage methods on soil physical properties was evaluated with complete randomized blocks. The results showed that different tillage methods had significant effect on bulk density, porosity and soil cone index. The greatest bulk density and acone index was attained in chisel plow and no tillage system, respectively. The tillage methods and cultivars had a significant effect on yield and yield components. Sardary cultivars produced more grain (1624 kgha-1) than Azar2, statistically. The greater yield was attained in chisel plow than other tillage methods. Chisel plow improved soil water and soil physical properties. Using chisel plow resulted in maximum 1000 seed weight and maximum grain number in spike. Tillage methods and the cultivars had a significant effect on plant height and biomass.

Suckers are strong sinks of water and nutrients, thus they have intensive competition with plant vegetative parts like scion of budded seedlings. This is an enormous problem of citrus nurseries in north of Iran. As far as vast input and time is spending on control of these unwanted suckers. This research, that carried out in design, compares 10 different sucker control methods in three citrus rootstocks (Troyer citrange, Sour orange and Citromelo) with five replications. Mean comparison of variables show that NAA with 2500ppm in twentieth day after budding and also aluminum foil treatment could control the suckers in respect to sucker number, length and leaf number, significantly better than other methods. Fresh weight of sprout in nursery trees without sucker removal treatments was the highest. In this variable, all NAA treatments, aluminum foil and two month manual removal, without significant difference, reduced the weight of suckers. Evaluation of variables related to scion vegetative growth indicate length, leaf number, total leaves surface and fresh weight of scion, in all sucker control treatments were significantly less than complete manual removal method. Scion performance was delayed significantly in high concentration of NAA (2000 and 2500ppm in twentieth day after budding).

Sclerotinia stem rot (SSR), caused by Sclerotinia sclerotiorum, is the most important diseases of canola (Brassica napus) in Iran. In order to study of the impact of SSR on canola yield, infection situation and yield of 80 fields in four different regions of Golestan province (Gorgan, Ali Abad, Kalaleh and Gonbad) in north of Iran, was recorded during two growing seasons (2006 and 2007). SSR severity was estimated 0.6-66.8% and yield loss due to the disease was 0.3-34.7%. Statistical relationship between SSR severity and field yield revealed that one percent increase in SSR severity, causes 0.52% yield loss, and this value corresponds to 0.25 and 0.4% SSR incidence in Gonbad and other three regions, respectively. Economical damage threshold of SSR in a canola field with potential yield of 2000 Kg/ha. was calculated as 17.2 and 10.5% SSR incidence for Gonbad and other three regions, respectively.

Studying the weed’s effect during period of plant growth is needed for economical and useful programming. In this paper two groups of treatments have been used. In the first group, weed and plant had competition form the beginning of growth period and then weeds were controlled at the certain time. In the second group, weeds were controlled from the beginning of growth period and at the certain time, were competed with the plant. At the end of growth period, the crop yield of both treatments have been measured and the variations of relative crop yield of treatments during growth period have been investigated, using Logistic and Gompertz functions. These functions describe the relationship between time and related yield, continuously. The independent variable in Logistic and Gompertz methods is end of control period and beginning of control period respectively. Critical point of weed control has been determined with calibration and parameter estimate of these two models. In all of past studies, CPWC has determined by accept of certain percent (5%) for allowable relative crop yield decrease. In this research, CPWC has been calculated based on economic decrease of crop yield. Therefore, this period has named as Economic Period of Weed Control (EPWC). EPWC, which is a function of income from one percent of crop yield to cost of one day of weed control in unit area, is calculated using dynamic programming. EPWC is annually updated, according to value of crop yield and cost of weed control for unit area. The results of this study show that the length of intersection point of Logistic and Gompertz curves is 27 days after planting of corn and critical point of weed control. 

In recent years, symptoms of a viral disease including streak mosaic, leaf blade malformation, and thickness (scrawniness) of raceme have been observed in the vast areas of grain fields in Golestan province. In order to identify the causes of this disease, detection of wheat streak mosaic virus (WSMV) in cultivated hosts including wheat, dominant weeds of fields involving barnyardgrass (Echinochloa crus-galli L.), johnsongrass (Sorghum halepense), Setaria glauca, Digitaria sanguinalis, Bromus spp., and Echinochloa colonum is done with mentioned symptoms. In the agricultural year of 2007, 700 samples of these hosts in the fields of the province, suspected of the disease, were prepared. These Samples were analyzed by indirect ELISA using WSMV polyclonal antiserum and a number of the infected samples were tested by PCR using WSMV specific primers involving RCF1, WSM1, WSMF10 and WSMF13 that were prepared from the 5' area of the virus’s protein capsid. Results of indirect ELISA confirmed the presence of this virus in the Digitaria sanguinalis and Echinochloa colonum, for first time. Positive reactions in the RT-PCR test with WSMV specific primers also showed the presence of this virus in only two hosts, Digitaria sanguinalis and Echinochloa colonum. We have no information about the scope of the damage in the fields of the province. In this research although in some cases wheat fields and wild weed in the fields and neighboring gardens showed the symptoms including mosaic, leaf curl, dwarfing and decrease of the growth, but the presence of this virus has not been detected in most cases. Investigation to detect the virus in native hosts involving wheat is continued in this province.

In order to study the effect of mineral nutrient and salicylic acid on the fruit yield and yield components of coriander, a study was conducted in experimental field of Gorgan University during 2007. The experiment was laid out in randomized block design with ten treatments (salicylic acid, Nitrogen, Phosphorus, Potassium, Magnesium, Zinc, Iron, Boron, Molybdenum and control) in three replications. The results showed that among the all evaluated traits, only 1000 seed weight did not respond significantly to treatments. In this case, effect of Phosphorus, Zinc, Potassium, Nitrogen and Molybdenum on yield, and effect of Nitrogen, Zinc, Potassium and Phosphorus on biomass “was significant than was significantly greater than control”. Plant height and number of branch per plant was enhanced significantly by Nitrogen, Phosphorus, Potassium, Molybdenum and Zinc. All treatments, except salicylic acid, increased number of umbel per plant significantly, and the number of umbel per plant had highest correlation with fruit yield.

During past few years, dying of apple trees in apple orchards of in Kohgiluyeh and Boyerahmad Province was observed. The symptoms of this abnormality were accompanied with wilting, general weakness, less growth of tree branches and leaves. Sometimes sudden dying during flowering and fruit harvest. In early spring up to end of summer of 2008, the sampling from collar and crown effected tissues from rotten root of infected trees were taken to isolate the causal agent of disease. Pieces of infected tissues were washed with tap water blotted dry and plated on CMA supplemented with delvocid, ampicilin, rifampicin and PCNB. Phytophthora colonies on the selective medium based on morphological characters produced and temperature requirement, the pathogen was identified as Phytophthora citricola. The sporangia were avoid to spherical, pyriform, with 1, 2 or occasionally with 3 prominent papilla, noncaducous with average dimension of 48.80 31.65. The optimum temperature for growth was 25 °C. P. citricola was pathogenic on 5 month old apple seedlings under greenhouse conditions and on branches of apple in laboratory.

Root-knot nematodes are one of the limiting factors in seedling production and new olive gardens establishment in Iran. In view of find resistance cultivars to root-knot nematodes, importance of careful identification of species and races are clarified. In order to investigate root-knot nematodes on olive, soil and root samples of gardens and nursery in Gorgan area were collected. In this study, Meloidogyne incognita was identified based on females and second stage juvenils morphometrical and morphological characters. Stylet length, body length of female nematode, tail and hyaline length of second stage juveniles were shown some differences with original description. In original description, body length of females was 500 to 723 micrometer (609 micrometer average), whereas in under consideration species body length was (512-751) 622 micrometer. In original description tail length of second stage juveniles was (45-52.2) 48.7 micrometer and hyaline was (6.3-13.5) 8.9 micrometer while in investigated species tail length and hyaline were (43.9-55.4) 52.1 and (10.6-14.2) 12.9 micrometer, respectively. In response to differential hosts, the nematode showed a good multiply on tobacco, tomato, pepper and watermelon plants and able to produce knot whereas response cotton and peanut plants were negative. On the basis of morphological and morphometrical characteristics of matured female, perineal pattern, second stage juveniles, and response to differential hosts of M. incognita race 2 was detected.