Seed and Plant
Year:2007 | Volume:23 | Issue:3|Papers Count:15

Rye is one of the troublesome weeds of wheat in Iran. To study the competitive ability of Iranian bread wheat cultivars agains rye, an experiment was conducted using factorial experiment based on randomized complete block design with four replications in Varamin and with three replications in Meshkindasht during 2002-2003 growin season. Treatments included eight Iranian winter wheat cultivars (Azadi, Mahdavi, Roshan, Tabasi, Pishtaz, Shiraz, Karaj2 and Nicknejad) with to levels of rye (with and without rye). Results indicated that Mahdavi cultivar had the most competitive ability againt rye with  lowest percent of garin yield loss (7.32%) in presence of rye, highest  grain yield (6.12 tha-1) and highest competitive index (2.16). Karaj 2 with the highest percent of garin yield loss (46.96%) in presence of rye, lowest grain yield (2.6 tha-1) and lowest competitive index (0.35) was the least competitive cultivar. Rye produced the highest and lowest number of spikes in presence of Mahdavi and Karaj 2 cultivars, respectively. Based on these results Mahdavi cultivar can be recommended for control of rye in a IWM program.

The peresent study was conducted to evaluate the side effects of combination cotton seed treatment with fungicides including Carboxin-thiram (WP 75), Carbendazim (WP 50), Triadimenol (DS 7.5) and insecticides Thiodicarb (DF 80) and Imidaclopride (SW 70), which are commonly used for control of early season insects and seedling diseases in cotton crop, on seed germination, seedling growth and damping-off control.  The laboratory and field experiments were arranged as factorial on the basis of randomized complete design and randomized complete block with five and three replications, respectively. The laboratory studies were carried out by rolled wet paper towels method. Results showed that, all Thiodicarb-fungicides seed treatments decreased seed germination and length of radicle, and increased seed rot, adventitues roots, diameter, dry weight, and animally of cotton seedlings. These interactions increased susceptibility of cotton seedlings to causal agents of damping-off and decreased seedling establishment in field conditions. Therefore, it has been concluded that use of Imidaclopride as chemical cotton seed treatment in combinations with a fungicide would have lower deleterious side effects on germination, emergence, seedling growth of cotton.

In order to select high yielding and most adaptable chickpea lines under dryland conditions, seven desi type chickpea genotypes together with one check cultivar (Pirouz) were evaluated in three research stations (Gerize, Kharke and Ghamlu) of Kurdistan province, during three years (2001-03) in RCB design with four replications. Bartlett test suggested that there was homogeneity in error of variances. Thus, analyses of variance were done to study the genotype-environment interactions, and analysis of stability was done to determine the performance of lines in varying environments. Results, of ANOVA showed that there were significant differences among environments, mean yield of genotypes and the G E interaction. Stability analysis after Eberhart and Russell method showed that there were significant variations due to genotypes, environment and their interactions for one hundred seeds weight, and due to environment for seed yield. On the basis of stability parameters (Pi, bi, S2di, and CV %), genotype ICCV 91006 with the highest seed yield (821 kgha-1) was selected as the most desirable and stable genotype.

To study the inheritance of resistance to powdery mildew in barley, four winter and facultative barley cultivars (Hebe, Afzal, Legia and Igri) along with six F1s, derived from monolateral diallel crossing, with Karaj isolate of the pathogen were examined in a complete randomized block design with three replications. The components of resistance including latent period and infection type were scored. Variance analysis revealed significant differences among genotypes for these two components. Among the parents, Igri possessed the greatest general combining ability for increasing the resistance. Among the hybrids, Afzal*Hebe and Afzal*Igri hybrids respectively possessed the most specific combining ability for increasing the resistance. The findings of the study showed that the frequency of dominant resistance genes was greater than non-dominant genes. General and specific inheritability were 98.3 percent and 36.5 percent respectively. The low figure for specific inheritability indicated that the type of selection would not be effective in decreasing the latent period and infection type characteristics. The extent of dominance for the two features of latent period and infection type were greater than 1, which confirms that genetic dominance and super-dominance were effective in controlling these two features.

To evaluate of the reactions of chickpea lines to drought stress during seed germination and later growth stages, 17 lines were studied under controlled conditions at four water potential levels and in field at optimum and water-limited conditions. Physiologic characteristics including leaf water potential (Yw), leaf relative water loss (RWL), and chlorophyll content (Chl) at flowering and pod filling stages were measured. The results showed that with decrease of water potential (0 to -1.2 Mpa), all characteristics of germination were significantly decreased. The highest germination stress index (GSI) was related to the lines Bivanij and Flip95-48C. Positive and significant correlation was observed between maximum germination (Gmax) and GSI. In field, drought stress reduced Yw in the both growth stages. Significantly reduction for Chl was not observed. Based on stress tolerance index (STI), lines 18-59-15 and Flip97-188C were superior to the other lines. In pod filling stage, the highest Yw was related to these two lines as well as line 12-60-31 under stress condition. In flowering stage, Flip89-50C, and in pod filling stage two above mentioned lines with the highest STI, as well as lines Flip93-166C and Flip95-42C had the lowest RWL. In the both growth stages, and both conditions, the highest Chl belonged to Flip94-111C. Under water-limited condition, Y whad negative and significant correlation with RWL in the both growth stages. Based on the obtained results, drought tolerance was related to high leaf water contents. The results of stepwise regression showed that biological yield in optimum condition; unfilled pod percent and grain weight in stress condition, as well as number of pods per plant had the highest effect on yield.

Trchoderma harzianum M, T. harzianum T39, T. viride(MO) and T. virens DAR74290 were used as potential  biological agents for control of wheat crown and root rot caused by Bipolaris spicifera. Dual culture and volatile test were used for antifungal activity of Trichoderma isolates. Percentage of growth inhibition of Bipolaris spicifera by T. harzianum M, T. harzianum T39, T. viride (MO) and T. virens DAR 74290 were 53.39, 37.37, 33.11 and 40.4 in dual culture and 71.5, 52, 66.5 and 5.64 in volatile test respectively. Results of glasshouse experiments indicated that T. viride (MO) was the most effective. All isolates reduced disease incidence and disease severity in microplot test. There was no significant difference between benomyl and Trichoderma treatments. The effect of benomyl and Trichoderma isolates was similar on reducing the disease. Disease severity in treatment of pathogen plus Trichodermin B, T. viride, T. harzianum varied from 0.74 to 1.63 compared to 3.07 in pathogen control.

Conservation tillage practices and proper seeding depth of wheat for early emergence before the first effective rainfall are very important in dryland cold regions. An experiment was conducted during 2001-2004 cropping seasons at the Dryland Agricultural Research Station, located in the northwest of Iran. The main objective of this study was to find the optimal seeding depth for wheat production in dryland. The treatments were, three wheat genotypes (Azer 2, Ogosta/ Sefid and Fenkang15/Sefid) as the main plot and three seeding depth (2-4, 4-6 and 6-8 cm) as subplots in strip plot design with three replications. Data were analyzed by the analysis of variance method. When the F-test indicated statistical significance at the 1% level, means were compared by the Duncan, s new multiple range test. Results showed that increase in seeding depth decreased number of heads per square meter, kernel size, biomass and grain yield significantly. The highest grain yield was obtained at 4-6 cm seeding depth in Azer 2 with 2580 kgha-1. Genotypes differed significantly in grain yield. Fenkang15/Sefid with 2149 kgha-1 had the highest grain yield. The number of heads per m2 had the main effect on yield increase. The highest number of heads per m2 (338 head per square meter) belonged to 2-4 cm seeding depth.

Two separate experiments were conducted to compare the total and marketable yield of eight potato cultivars in winter and autumn planting for selection of adapted cultivars to Khuzestan conditions. The experiments were carried out at Behbahan Agricultural Researeh Station from 1999 to 2001. The first experiment began in January and eight cultivars were compared in a RCBD with four replications. Tubers were planted late in January and harvested in mid May. In the other experiment, the same cultivars were planted early in October and harveted late in February.  Frost occurred in November 30 in 1999 and January 25 in 2001. After harvesting, yield of each cultivar was separated into marketable and unmarketable. At the end of experiments total and marketable yield of autumn and winter plantings were analyzed by split plot design in time. According to the obtained results cultivars Binella, Arinda, Sante, Cosmos and Ajax were recommended for winter planting and Sante for autumn planting. Due to the probability of frost occurrence in autumn planting, winter planting is prefered to autumn planting in Khuzestan conditions.

In order to select adapted and high yield barley varieties, regional yield trials were carried out using a RCBD design with 24 barley genotypes in Maragheh, Ardebil, Zanjan and with 22 genotypes in all locations Maragheh, Ardebil, Kermanshah, Kordistan, Shirvan and Zanjan. These experiments were conducted with four replications in three years (2001-2004). Simple and combined analyses of variance in all locations were done separately. Fmax Hartely used to assess the homogeneity of the error variance at various, showed that the errors variance were homogeneous. Combined analyses were done once with 22 genotypes in all rejoins then with 24 genotypes in Maragheh, Ardebil, Zanjan stations. The results showed that there were significant differences (P1 %<) among all simple and interactions effects. Locations combine analysis showed that there were significant differences (P1 %<) among genotypes for all regions. In all regions two genotypes No. 3 (Alpha/Gumhuriyet//Sonja) and No. 5 (B-c-74) (from 22 and 24 sets) and genotype No. 9 (Antares/Ky36-1294//SlrIcbh-0383-OAP-OAP-OAP-8AP-OAP) from 24 genotype set  were high yielding genotypes.  Yield stability analyses were done for different genotypes by Lin and Binns, environmental C.V, cluster analysis and Rank methods. The results of Rank method proved that genotypes 3 and 5 (from two experiments) and genotype no. 9(from 24 set) were stable. Based on environmental C.V and Lin and Binns variance method genotype No. 5 identified as a stable genotype. Meanwhile in cluster analysis stable genotypes in the last methods and genotype No. 4 were classified in Sahand check group, so stability of those genotypes were confirmed. The genotypes No. 3, 4, 5 and 9 (from 24 set) had the highest yield among all stable genotypes and were comparable with check cultivar Sahand.

This experiment was conducted for three consecutive years from 2000 to 2002 to evaluate the effects of integrated weed management on weeds of alfalfa at the Safi Abad Agricultural Research Farm of Dezful. The experimental design was a randomized complete block with strip-split plot arrangement of treatments. Herbicide treatment was as horizontal factor at five levels which in 2000, consisted of application of bromoxynil at 0.45 kg ai /ha at the 2 - leaf stage of alfalfa + metribuzin at 0.35 kg ai /ha after the cutting for seed, application of bentazon at 0.96 kg ai/ha at  the 6 - leaf stage of alfalfa + metribuzin at 0.52 kg ai/ha after the cutting for seed, application of bentazon at 0.96 kg ai /ha at the 6 - leaf stage of alfalfa + bentazon at 1.44 kg ai /ha after the cutting for seed, weed free and weedy checks. Cultivation was as vertical factor at three levels which in 2000, consisted of reciprocal application of shovel cultivator and rolling + shovel cultivator when alfalfa was 30 cm tall and after the cutting for seed and noncultivated plot. In 2001 and 2002, treatments were applied after the cutting for seed and were as follows: application of metribuzin at 0.35 and 0.52 kg ai/ha, bentazon at 1.44 kg ai /ha, weed free and weedy checks, and cultivation treatments were as abovementioned treatments. In 2000, total number of broadleaved weeds were reduced by application of bromoxynil + metribuzin, bentazon + metribuzin and bentazon + bentazon by 77, 81 and 56%, respectively, and on average, by cultivation by 59%. In 2001, total number of broadleaved weeds were reduced by application of metribuzin at 0.35 and 0.52 kg ai/ha and bentazon by 83, 95 and 83%, respectively, and in 2002, by 68, 87 and 65%, respectively, by the aforementioned herbicide treatments. Compared to the weedy check, alfalfa seed yield increase in application of metribuzin at 0.35 and 0.52 kg ai/ha, bentazon and weed free check treatmensts was 51, 11, 83 and 37%, respectively.

In order to determine the best cultivars and planting date of oilseed rape, an experiment was carried out in two years (2000-2002) at Agricultural Research Station of Haji Abad. The experiment was a split plot design on randomized complete block basis with four replications. The main plots included four planting date (22 Oct. 31 Oct., 10 Nov. and 20 Nov.), and the sub plots included three cultivars Sarigol, Hyola 401 and Option 501). The results of combined analysis showed that effects of year, planting date, cultivar and interaction between them were significant on number of days from emergence to flowering, duration of flowering and physiological maturity at the 1% level. Cultivar Hyola 401 had the lowest and Sarigol had the highest number of days from emergence to fowering and physilogical maturity. Hyola 401 had the highest and Sarigol had the lowest duration of flowering. In planting date treatment, all characters decreased with delay in planting. The effect of cultivar was significant on number of pods per plant and 1000 seed weight at the 1% level, and Hyola 401 hybrid had the highest 1000 seed weight. The effects year ad cultivar was significant on seed weight at the 1% level. Hyola 401 hybrid produced the highest seed yield (2597 kgha-1(.

Maize rough dwarf virus and Iranian maize mosaic rhobdovirus are common diseases in Isfahan province and Laodelphax striatellus is the only known vector of them. Relationship between the vector and these viruses was studied in an experimental field. Population density of the vector and viral infection rate were studied by weekly samplings until tasseling stage. Curves of population fluctuation of the vector and cumulative infestation rate of viruses were developed. Results showed higher density of the vector in the beginning of plant growth period for the first and second dates and at the end of growth period for third date. Cumulative infection curves showed an increasing trend for both viruses in all treatments, while it reached to a stable position after tasseling stage. To study the effects of asynchronous cropping system on density of the vector and viral infection rate, side-by-side fields with different planting dates in different regions of the province were sampled. The results of this survey showed that maximum and minimum viral infection rate and vector density belongs to regions of Baraan and Ardestan, respectively. This situation could be related to variation of planting dates in these regions. It is recommended that in each region corn fields should be planted synchronously as possible, and late planting be avoided.