Seed and Plant
Year:2003 | Volume:19 | Issue:1|Papers Count:6

Septoria leaf blotch is one of the most important diseases of wheat in the world. Severe epiphytotics of the disease occurred in Iran, especially in Khuzestan province during 1996. In an attempt to assess the adverse effects of infections of the disease on yield of 3 main wheat cultivars, a field trial for two years was carried out using a split - plot desing, where the main plots consisted of artificial inoculation at 14-18 day intervals at growth stages GS__12, GS__23, GS__31, GS__37, GS__47&GS__58 corresponding to 17, 33, 51, 66, 81 and 95 days post planting. The subplots were cultivars Falat, Atrak and Darab-2, that were planted in a randomized complete block design in 4 replications. A control of plain water spray was included in the experiments. Indices taken were: grain yield, number of ears per square meter, number of kernels per ear and 1000 kernel weight. Linear regression of mean yield loss and the number days of infection was plotted. Under the conditions of these experiments, yield reduction of 6.99 to 38.20 percent were recorded. The extent of yield reductions depended on the wheat cultivar, its growth stage at the initiation (time) of infection, and the severity of the disease. The disease caused significant reductions in grain number per ear and I000 kernel weight; however, the number of ears per square meter was not affected. Daily reductions of 0.283, 0.249 and 0.301 per cent in yield were caused due to disease in the cultivars Falat, Atrak and Darab-2, respectively.

In order to study the effects of planting arrangement and weed control on yield and yield components of cv. Akhtar, a red bean cultivar (Phaseolus vulgaris), an experiment was conducted at the Khomein National Bean Research Station during 1998-99, using a split plot design in randomized complete block with three replications. Four planting arrangements (50 ×5, 37.5 ×6.7, 25 ×10 and 18.75 ×13.3 cm) in main-plots, and two levels of weed control (weeding and unweeding) in sub-plots were considered. Results of combined analysis of variance revealed that planting arrangement had significant effect on grain yield. Decreasing row spacing and increasing plant spacing increased the grain yield, and in 37.5 × 6.7 cm treatment, the highest grain yield was obtained. Yield components were not significantly influenced by planting arrangement. Weeding was found to be an effective factor in increase of yield and its components. Plant height was also increased in free-weed plots. Unweeding caused yield decreases, so that the grain yield decreased by 41.2% compared to weeding treatment.

In order to evaluate effects of planting density and depth on growth and yield of potato cultivar Diamant, an experiment was carried out in 1998 in Mianeh located in East Azarbaijan. A factorial experiment with randomized complete block design and three replications was used. Three planting densities 45000, 55000 and 65000 plant ha^ -1 (30, 24 and 20 cm between plants on 75 cm rows, respectively) with four planting depths 5, 10, 15 and 20 cm were used as experimental factors. Tuber yield, plant development and other traits were significantly influenced by planting density. Density of 55000 plant ha^-1, caused longer period of emergence and tuber set, higher stand percentage, higher number of tubers per unit area and tuber yield, compared to the other densities. All of the measured traits were affected by planting depth. Stand percentage, number of stems per plant and per unit area, main stem length and percentage of tuber lost were decreased as planting depth increased. Number of days to emergence, tuber set and flowring increased with increasing planting depth from 5 to 10 cm and from 10 to 15 cm, then decreased from 15 to 20 cm. Planting density and planting depth intraction significantly affected the number of days from planting to flowering. The earliest date of flowering was occurred with density of 65000 plant ha^ -1 planting depth of 15 cm and the latest with 45000 plant ha -1 at depth of 5 cm.

To determine relationship between different traits with grain yield, 100 lines and cultivars were studied in a simple latice design. Twenty traits such as grain yield, yield components and some grain and plant morphologic characters were evaluated. Results showed that grain yield had positive and significant simple correlation with days to 50% flowering, number of panicle per plants, flag leaf width, total number of grain per plant, number of tillers per plant, and 100 grain weight. Factor analysis showed that 87 percent of total variations were determined by six independent factors. So that, they were nominated in four factors under the titles of morphology, grain size and shape, yield and yield components and grain filling. In yield and yield components, traits such as number of panicle per plants, plant weight, number of grain per panicle showed high correlation with each other. Using path analysis, it was demonstrated that the increase in grain yield is largely due to increase in plant weight.

Genetic diversity of 38 Taree Irani (Allium ampeloprasum ssp. persicum) genotypes collected from different parts of Iran were investigated during 1999-2000 at the Horticultural Center, Faculty of Agriculture, The University of Tehran. using morphological characters. Based on descriptors, 45 characters were studied. According to the cluster analysis four different groups, each containing 1,3,3 and 31 genotypes were determined. Having special characters such as early flowering and different flower organs color, Ahvas 19 genotype felt in the 1 st. group individually. Zabol 24, Fars 40 and Hamedan 49 genotypes felt in the 2nd. group and Azarbaijan Gharbi 27, Hamedan 47 and Hamedan 50 in the 3rd. group. The remaining 31 genotypes felt in the 4th group. Genotypes of this group were late flowering and compared with the 1 st. group had different flower organs color. Second and 3rd. groups were intermediate in characters. Based on clustering yield components, of different genotyps, 11 superior genotypes, all from the 4th. group, were identified. There was also positive correlation between date of flowering and dominant flower organs color. No significant correlation was found between origin and genetic distance of genotypes.

An experiment was conducted at Zahak Research Station in Zabol in 1996-97 to determine the best method of planting and plant density for mixed culture of cucumber and eggplant. In this experiment, yields of two crops were compared in individual and mixed cultures. In both systems the distances between two plant were 25 and 50 cm, and in the mixed culture eggplants were planted in the opposite of cucumbers (zig zag form). The results showed that in individual culture, the yields of cucumber with 25 cm distance and eggplant with 50 cm distance between plants were 51.1 and 55.7 tha__-1, respectivety, but in mixed culture, where the eggplants were planted in zig zag form with 50 cm distances between cucumber plants, a told yield of 78.3 tha-1 was obtained. The relative yield and LER were determined to be 202 and 1.53, respectively.