فصلنامه علوم زراعی ایران
سال هشتم شماره 4 (پیاپی 32، زمستان 1385)

This experiment was conducted in 2002 to 2004 to evaluate the co-efficacy of reduced rates of herbicides and cultivation for weed control in sugar beet at the Safiabad Agricultural Research Center of Dezful and Agricultural Research Station, Boroujerd, I. R. Iran. The experimental design was a randomized complete block with stripe plot arrangement of treatments with three replications. Cultivation was as vertical factor at three levels including: application of shovel and blade cultivator at 6 to 8 leaf stage of sugar beet and repeating it one month later, and uncultivated treatments. Herbicide application was as horizontal factor at eight levels including: application of chloridazon + phenmedipham at 3.2 + 0.78 and 2.4 + 0.63 Kg ai ha-1, phenmedipham + desmedipham + ethofumesate at 0.54 and 0.72 Kg ai ha-1 at 4 to 6 leaf stage of sugar beet, triflusulfuron at 10 and 15 g ai ha-1 at cotyledon leaf stage of sugar beet, weed free and weedy controls. Results showed that in 2002, at Safi Abad and Boroujerd application of chloridazon + phenmedipham at 2.4 + 0.63 and 3.2 + 0.78 Kg ai ha-1 were effective treatments in controlling broadleaf weeds and had also the highest level of sugar beet root yield after the weed free controls. In 2003, at Safiabad, application of phenmedipham + desmedipham + ethofumesate at 0.72 Kg ai ha-1 was the most effective treatment in controlling broadleaf weeds, but in Boroujerd there were not significant difference among herbicide treatments and application of chloridazon + phenmedipham at 2.4 + 0.63 Kg ai ha-1 and triflusulfuron at 10 g ai ha-1 had the highest level of sugar beet root yield after the weed free control at Safiabad and Boroujerd, respectively. Application of shovel and blade cultivator compared to uncultivated plots increased sugar beet root yield by 11 and 27%, respectively. According to this experiment application of chloridazon + phenmedipham at 2.4 + 0.63 and 3.2 + 0.78 Kg ai ha-1, phenmedipham + desmedipham + ethofumesate at 0.72 Kg ai ha-1 at 4 to 6 leaf stage of sugar beet and triflusulfuron at 10 g ai ha-1 at cotyledon leaf stage of sugar beet together with the application of shovel or blade cultivator at 6 to 8 leaf stage of sugar beet repeated at re-emergence of weeds is recommended

The length of growing period (LGP) has been defined as the period of the year in which agriculture production is possible from the viewpoint of moisture availability and absence of temperature limitations. Temporal variability of growing period and its parameters are necessary quantifying and predicting some information in agricultural and natural resources. This information can be effective in making decisions in planting date and excess water requirement to access the potential yield in rainfed agriculture. In rangeland and forest use of these data are also valuable in management and species selection. Fractal analysis can be used to differentiate between short- and long-term variation for parameters collected in time and space. This study conducted on climatic data collected from synoptic station of Ghaem-shahr located in Mazandaran province in order to study temporal variability of growing period using fractal analysis. Climatic data were chosen to calculate growing period and humid period length for 44 years since 1959 up to 2003. Then semivariances were determined using variography analysis and log of semivariances VS. log lag (year) were plotted to calculate D-dimension values for each of periods. The result of study showed that D-dimension values were 1.99 and 1.96 for LGP and length of humid period respectively. The high amount of D-values indicated that these periods follow small-range variation during the time and had high fluctuation year to year. This information is valuable for management purposes. The result of this study also indicated that fractal analysis can be used to studying temporal variability of growing period over time.

Major lentil growing areas in Iran (93%) are in rainfed condition. Therefore, It is important to find genotype or genotypes with high yielding, Stable and adapted to rainfed conditions. The objective of these research was to study the stability of grain yield and adaptability of genotypes in promising lentil lines under dryland conditions. Experimental material included 11 lentil genotypes were studid using randomized compelet block design with four replications at Kermanshah, Lorestan, Shirvan, Ilam and Gonbad field Research Stations during three successive grwoing seasons (2001-04). The results of combined analysis of variance showed that year × location, genotypes × location, year × location × genotypes were significant at 1% level of probability. Statistical methods used for measuring yield stability were coefficient of variation (C.V.), Shokla's stability variance, Wrick's ecovalance, rank-sum method, coefficient of determination (R2), non-parametric methods of rank and simultaneous selection for yield and satbility. On the basis of regression coefficient of Finlay and Wilkinson genotype FLIP 96-9L, FLIP 96-4L, ILL 6037 and FLIP 92-15L had general adaptability to over environments and genotype FLIP 92-12L was suitable for favorable environments. The result of coefficient of variation indicated that genotypes FLIP 92-12L, FLIP 82-1L, ILL 6037 and FLIP 96-4L were the most stable genotypes. Shokla's stability variance, Wrick 's ecovalance and rank-sum method introduced genotypes FLIP 82-1L, FLIP 92-12L and ILL 6199 as more stable and adapted genotypes. The highest coefficient of determination (R2) belonged to genotype FLIP 92-12L. Result of stability analysis on grain yield using non-parametric methods of rank and simultaneous selection for yield and satbility showed that genotypes FLIP 92-12L and FLIP 82-1 L were superior for stability and adaptation. Based on stability parameters, it can be concluded that genotypes FLIP 92-12L and FLIP 82-1 L were the more stable genotypes.

In order to determine the effects of water deficit and different nitrogen levels on seed yield, yield components, water use efficiency, nitrogen utility efficiency and uptake in rapeseed, a field experiment was conducted using a factorial split-plot in randomized complete block design in 2005 growing season. In this study, two cultivars (Zarfam and Modena), three water regimes (irrigation after 40, 60 and 80 percent depletion of soil water) and four nitrogen levels (0, 75, 150 and 225 Kg/ha) was studied. Results showed that increasing the nitrogen rate from 0 to 220 kg/ha and increase in soil water, caused increasing the total biomass production that was accompained by increasing the seed yield. Increasing the seed yield, was related to increasing the number of pods per plant and number of seeds per pod in both conditions. With increasing the ntirgoen and soil water, water use efficiency (seed and total biomass) was increased. The maximum rate of these efficiency, obtained from 220 kg N and 40 percent depletion of soil water. Nitrogen accumulation in all plant organs and nitrogen uptake, increased with increasing nitrogen and watering times. In contrast, nitrogen utility efficiency decreased with increasing nitrogen used and decreasing soil water that finally improved the seed yield and total biomass. Zarfam had a higher nitrogen uptake and mobilization under normal irrigation and severe water stress conditions, and also in higher and lower nitrogen conditions and produced higher seed yield.:

In order to determining and identification of the nature of gene action in inheritance of different traits, 56 genotypes (crosses and reciprocals) developed from diallel crosses of eight maize inbred lines along with parents were evaluated for important quantitative traits using randomized compelet block design with three replications in the Experimental Field Station of Seed and Plant Improvement Institute, in 2005 cropping season. Diallel analysis revealed the presence of over-dominance gene action in controlling grain yield, kernel number per ear row, kernel depth, ear length, plant height. Genes with partial dominance action were revealed in controlling number of rows per ear, numer of leaves and days to tasseling, while genes controlling 300 kernel weight and ear diameter showed dominant effects. Graphic analysis showed that for early reproduction stage, and increasing the grain yield, member of rows per ear and kernel number per row, length and diameter of ear, leaf number, plant height, dominant genes ware involved, while, for 300 kernels weight, recessive genes were effective.

A field experiment carried out to evaluate genetic diversity in 76 peanut accessions (Arachis hypogea), obtained from National Plant Gene Bank of Iran, in the faculty of Agriculture, the University of Guilan, Rasht, Iran. Eleventh major morphological traits were recorded using ICRISAT Peanut Descriptor during 2002 growing season using a Randomized Complete Block Design (RCBD) with two replications. Application of Pearson correlation indicated that seed length, seed width, pod length and width had a direct positive relation to seed weight (P≤0.01). In addition, the number of pods per plant had a positive correlation with number of seeds per plant and pod weight (P≤0.01). Three components derived from principal component analysis accounted for nearly 72% of whole variability in the evaluated germplasm, defined by number of seeds per plant, pod weight, seed length, seed width, seed weight, number of pods per plant, pod width and pod length. The accessions were divided to three groups by cluster analysis based on Ward method using Squared Euclidian distance coefficient. The studied accessions showed high similarity (0.19), therefore, broadening genetic base of peanut germplasm and use of molecular markers could be suggested in order to complete the morphological traits-based classification and evaluation of genetic diversity in peanut germplasm.

To study the inheritance of stripe rust resistance and to estimate the genetic components of resistance in wheat, F1, F2, BC1 and BC2 generations derived from a cross between MV17 as resistante and Bolani as susceptible parents together with parental lines were evaluated in a randomized complete block design (RCBD) with three replications in the greenhouse. The plant materials were inoculated with pathotypes 134E134A+ and 166E134A+ of stripe rust in two different experiments. In all plants, resistance components including latent period (days from inoculation to first pustule eruption) and infection type were recorded after appearance of pustules on leaves. Generation mean analysis revealed that additive, dominance and epistasis (especially [j] and [l] components) play a major role in increasing and decreasing of latent period and infection type, respectively. In spite of significant additive effect, dominance gene effect was the most important component in controlling these two characteristics. Estimates of degree of dominance were very close to unity for the two concerned traits in response to both pathotypes which indicates a complete dominance resistance. Heritability ranged from moderate to high and number of segregating genes governing resistance ranged from 1 to 3.