JOURNAL OF AGRICULTURAL SCIENCE AND SUSTAINABLE PRODUCTION
Year:2001 | Volume:11 | Issue:3|Papers Count:11

In order to investigate the processes of flower bud initiation, differentiation and stages of morphological development microscopically in apricot, an experiment was conducted in Sahand Horticultural Researches Station, in 1997 Starting early August, samples of flower buds on spur of cv. Shastemy-e-yek were taken every 10 days and after removing the scales under binoculars and fixing the buds in the F.A.A. solution, microscopic slides were prepared after washing, dehydration, paraffin infiltration, and embedding of the samples and after staining them the preparations were studied. The results revealed that the onset of organogenesis i.e. flattening of meristem took place early to mid August. The subsequent organogenesis such as sepal primordia formation occurred mid till the end of August, petal primordia from late August till early September, and stamen primordia from early till the mid September respectively. Pistill development began in synchrony with development of flower organs and it developed within several weeks. Hence, primordia of all flower organs developed early in November.

During 1996 growing season the effects of two row width (55 and 70 cm) and four planting densities (3.0, 4.5, 6.0, and 7.5 plants per square meter) on growth of three potato varieties (Draga, Aola, and Kasmoos) were studied by using a split plot design. The results suggested that row width has nonsignificant effect on morphological characteristics, while increasing planting density from 3.0 to 7.5 plant m2 reduced leaf area, number and mean height of stems, stolon length, and total dry weight per plant but increased their amounts per square meter. It also revealed that the responses of varieties to plant density were different. Aola cv. had greater leaf area, leaf area index, stem number and height than the two other varieties. Kasmaos cv. had the most stolon length and dry weight. Draga cv. produced the maximum leaf area in early stage of growth, This was anticipated to be due to its early emergence. It seems that environmental responses of potato genotypes were different. The leaf area and leaf area index variation with time (weeks after planting, WAP) followed a quadratic relation; maximum achieved at 12WAP. Number of steems per plant, depending on cultivar, row spacing and plant density, showed either quadratic or tertiary types of relations with WAP. Total dry matter versus WAP followed a cubic form of equation reaching to its maximum at 10 WAP and declined thereafter.

In this res arch, a seed-drilling machine with appropriate size was designed for small farms using Auto CAD software. Then three dimensional sample of the machine was prepared by computer and its operation was simulated and recorded on videotape. When the engineering drawings were prepared, the required components were constructed and the machine was assembled according to the drawings.Preliminary workshop evaluation, using polyethylene balls with 3mm diameter, showed that there was a linear relationship between speed and the amount of seeds planted within the range of 2 to 5 kilometer per hour. With regard to mechanical damages of the balls three pieces of seed metering device (selector wheel) with different types of seed cells were constructed and mounted on the machine. The following workshop evaluation confirmed the suitability of the cell type C in which the lowest percent seed damage namely 1.24 percent and percent cell fill of about 97 at traveling speed of 3 kilometer per hour occurred. The work was followed by evaluation of the seed drill on the sand type seed bed and in the field respectively, and its performance was compared with pneumatic German made seed planter. In sand bed tests there was a significant difference between two types of planters at 1% probability level with regard to mean seed spacing, feeding quality, multiple planting, skips and planting depth indices. According to field test results carried out on two types of planting beds, there was a significant difference between two planters with regard to mean plant spacing and accuracy range of 2 indices as well as feeding quality, multiple planting, skips, percent of germination, deviation from planting line and plant leaf area and dry weight of plant indices at 1% probability level and mean planting depth and hypocotyls diameter indices at 5% probability level. Since the evaluation of the selector wheel was carried out for only one seed size of the seed, therefore further investigations are need to be made with regard to different types of ce& before different types of selector wheels according to seed size and planting spacing are recommended and constructed. To improve other indices and also to improve planting conditions of the seeds and to increase the field emergence rate for the manual planter it is suggested that further investigation of seed delivery tube as well as soil engaging components be made and after making necessary modifications, a laboratory soil bin test as well as field test be carried out for the planter.

In order to evaluate the effects of supplemental light and its economic feasibility, in lettuce monoculture and its intercropping with tomato, two separate experiments in closed sand culture, were conducted in a complete block design (and without supplemental light) with four replicates in Khallat-Poushan research station situated 7km of east Tabriz. Pooled analysis of variance indicated that, the use of supplemental light increase the dry and fresh weight of lettuce and yield of tomatos from first cluster. Use of supplemental light did not have significant effect on both the number of fruits developed in cluster and the internodes length of tomato plants. Light treatment reduced effectively the number of days needed in developing the first inflorescence in tomato plants. The evaluation of economic feasibility of intercropping of these two vegetable crops showed that yield increase due to supplemental light could not compensate the electrical energy costs, so it appears that due to prevailing local winter natural high light intensity, the application of supplemental light would not be regarded as a beneficial procedure.

Twenty different cultivars of potato were evaluated for their relative resistance to the Colorado Potato Beetle, Leptinoiarsa decemlineata (Say), (CoL Chrysomelidae) and the mechanism involved at the agriculture research stations of Allarough and Hassan barough in Ardabil in the field during 1997 and 1998. The cultivars were: Fresco, Premiere, Caesar, Idole, Casmose, Desiree, Ajax, Cardinal, Mondial, Remarka, Oblixe, Picaso, Vital, Apollonia, Marfona, Concord, Qaster, Carlita, Draga and Aula. In a laboratory experiment second instar larvae of the beetle were confined on the fresh leaves of different cultivars in a repeated experiment and the mean amount of leaf eaten and the weight gain of the larvae were calculated and used as indices of antibiosis. In a Choice Test experiment that was conducted in the field, the number of adult beetls observed on each of the cultivars was determined 24 hours after their release and used as an index of antixenosis. To delineate tolerance, cultivars were planted in pots in a Randomised Completely Block Design and were infested with an equal number of first instar larvea. screen cage of suitable size was placed over each pot. At the end of the season, the tuber yields was harvested and compared. There was no indication of antixenotic and antibiotic resistance among the cultivars. However a significant difference in percent of reduced yield and damage at infested and noninfested pots was found that indicates the existence of difference in the tolerance of cultivars against the pest. Therefore, it was suggested to further study the genetic basis of the tolerance in order to use in an IPM program of the Colorado patato beetle.

In this study, the effect of incorporating pasta regrinds with the flour used for producing of sapghetti was investigated .Experimental treatments were produced by mixing of flour with 0 (blank sample), 5,10,15,20,25,50 and 100 percent pasta regrinds, respectively. Spaghetti was produced in a semi-continuous process at Shiar Macaron Factory. Quality experiments such as cooking quality tests (determination of cooking loss percent and cooked weight) and sensory evaluation by trained test panel were the major tests that accomplished on products. The results of experiments showed that with increasing the amounts of regrinds, quality of spaghetti decreases but no considerable difference was observed between blank sample (0%) and with 5, and 10 percent treatments. Whereas further increase in regrind percent i.e. 15% and more, caused considerable reduction of final quality in spaghetti. Finally, the results of this study showed that addition upto 1-0% pasta regrinds has no adverse effect on final quality (obtained by sensory evaluation) and cooking quality of spaghetti.

Entomopathogenic nematodes (Rhabditida: Heterorhabditidae and Seinemematidae) are obligate parasites of insects. These nematodes have a symbiotic association with bacteria of the genera (Photorhabdus for Heterorhabditis and Xenorhabdus for Steinemema). The infective 3rd-stage juvenile, the only free living stage, harbors the bacteria in its intestine. Upon encountering a susceptible host, the infective juvenile enters it through natural openings (mouth, anus or spirac1es) and penetrates into the insect homocoel where it releases the bacterium. The bacterium multiplies, killing the host within 48h. To evaluate the efficacy of entomopathogenic nematodes as potential control agents against this insect pest, experiments were arranged in completely randomized design. In 1998-1999 Steinemema sp. and Heterorhabditis sp. were used at rates of, 0, 10, 20, 40, 80, 160 individualsper cm2 of soil. The experiments were conducted in 9x19cm pots containing a sandy-loamy soil mixture. Nematodes at the above mentioned rates suspended in 20cm3 distilled water were sprayed on to the surface of the soil in the pots. After releasing 20 last-instar larvae in each pot, the pots were covered with gauze. After 15 days imagines appeared in the pots, and their number were recorded .The results demonstrate that Steinemema sp. and Heterorhabditis sp. at the rate of 160 individuals per cm2 were able to parasitize 85.63% and 90% of the pest larvae, respectively. The differences were significant at P=1 %in comparison with 10 and 20 individuals/ cm2.

Pseudomonas syringae is one of the phytopathogenic bacteria with larg genetic, physiological and biological variations. In this study, resistance of P.s. pv. syringae and P.s. pv. tomato were examined under both dry and humid conditions.P.syringae was susceptible to drought and it did not survive after three hys on the surface of teflon, filter paper and surface of tomato seeds. Various inoculums used that were under relatively low humid condition caused rapid death of bacterial cells. Hrp genes had an important role in multiplication of bacteria, however, no major role was observed on the survival of bacteria on seed and inert materials. In contrast, after germination of seed and development of seedling, the population dynamism of hrp mutant strains was significantly lower than those of wild strains. Seed infestation by P.s. pv. tomato occurred at low frequency even on heavily infected plants. The results of this study show that survival of P.syringaefrom one year to another can occur through other ways such as, soil infection and plant debries.

The crude protein degradability of feedstuffs is a important factor for providing of complement requirements of rumen microorganisms. This experiment was conducted using two fistulated-sheep and nylon bag technique for determination of dry matter and crude protein degradability of second-cut alfalfa, red clover, wheat barley grain, cotton seed meal and corn grain. Crude protein, Ether Extract and Ash Values were 22.64, 1.97, 10.2 and 17.71, 1.48,9.64 and 39.65,8.08,6.26 and 14.31, 2.6,5.2 and 9.07, 4.2, 1036 and 10.62, 2.12, 2.43 percentage for alfalfa hay, red clover, cottonseed meal, wheat brain, corn grain and barley grain respectively. The means and standard deviation of in situ degradabilities of dry matter and Curde Protein were in alfalfa hay: 47± 1.41 and 54.89±1.81, red clover: 51±1.1 barley grain: 69±3 and 68±2.5, corn grain: 64±0.7 and 62±1.4, w±eat bran: n.15±0.21 and 87.5±1.47 and cottonseed meal: 47.5±0.7 and 45.5±0.7 respectively. The result obtained from degradability study in this experiment can be used for calculating metabolizable protein in balanced ration formulation.

In order to assess the relative resistance of four onion cultivars, i.e. "Red Azarshahr”, “GholiGhessai Zandjan", "Yellow sweet Spanish" and Indian, to Fusarium, an experiment was performed in 1996.The infected plants were collected from onion fields around of Tabriz. Then Fusarium species were isolated and were recognized as follows: i) Fusarium oxysporum ii) Fusarium solani iii) Fusarium equiseti.Four onion cultivars planted in pots were treated with three above mentioned species of Fusarium and a control (sterilized soil) in a factorial experiment based on "completely randomized design", observations was made at seedling and adult plant stages. In both stages an effect of F. oxyspornm was significantly more than the other two species, but there was not a significant difference between F. solani and F. equiseti. There was no significant interaction of cultivar by species. The differences between cultivars was significant at the adult but not at the seedling stage. Also in the adult stage, the yield and root weight of cultivars were measured. Indian and red Azarshahr acquired the highest yield among cultivars. The yield of "Gholi Ghessai Zandjan" was more than "Yellow sweet Sapnish" and less than the other two. There were no significant differences among the "Gholi Ghessai Zandjan", "Red Azarshahr" and "Indian" cultivars in terms of resistance to Fusarium, but the relative resistance of "Yellow sweet spanish" was significantly less than Indian and "Red Azarshahr" cultivars. However it did not show significant differences with "Gholi Ghessai Zandjan". Indian cultivar had more root weight than other cultivars. Due to the fact that the Indian cv. produced the highest amount of roots and this might be the cause of the resistance to Fusarium, we can conclude that this cultivar is preferable to the other three cultivars.