Iranian Journal of Crop Sciences
Year:2006 | Volume:7 | Issue:4|Papers Count:9

In order to study growth indices, morphological and physiological traits, grain yield and its components in rice landraces and Improved cultivars, a field experiment was carried out in the Rice Research Institute of Iran (Amol) located in the north of Iran in 2003 cropping season. This experiment was laid out in randomized complete block design with three replications, Eight improved cultivars; Neda, Dasht, Fajr, Pouya, Khazar, Shafagh (Indica), Onda, Fuji Minori Japonica and two landraces; Tarom and Ramazan Ali Tarom were studied. Because of the differences in developmental pattern among the cultivars growing degree days (GDD) was used instead calendar days in calculating growth indices. Growth indices (Crop Growth Rate = CGR, Relative Growth Rate = RGR, Net Assimilation Rate = NAR, Leaf Area Duration = LAD, Leaf Area Ratio = LAR, Leaf Area Index = LAI) and traits such as number of vascular bundles, flag leaf angle, SPAD value, peduncle length, internode length, tillering capacity and plant height were measured. Results showed that growth indices (TDM, CGR, SLW and LAI) of improved cultivars were greater than landraces. But RGR and NAR of landraces were higher than improved cultivars. Neda had the greatest LAI (5.7) and highest grain yield. Cultivars which had the greatest and the lowest TDM, had the highest and the lowest grain yield, respectively (Onda and Ramezan Ali Tarom). In this study, landraces had taller plant height, less tillering capacity and lower grain yield than improved cultivars. The modern cultivars had greater number of vascular bundles and flag leaf vein than landraces. Onda had the greatest SPAD value (48.35). Neda had the highest panicle/m2 because of greater fertile tillering number. Indica improved cultivars, due to high tillering capacity, Total Dry Matter, Crop Growth Rate, Leaf Area Index and Harvest Index had higher grain yield. However landraces had lower tillering capacity, Total Dry Matter, Crop Growth Rate, Leaf Area Index and Harvest Index therefore lower grain yield. It is concluded that increasing grain yield in rice can be achieved ruough increasing total dry matter and improveing physiological indices.

In order to determine DRIS norms for irrigated wheat, 982 plant samples were collected from Irrigated wheat pilot project in East Azarbayjan (Tabriz, Maragheh, Marand, Mianeh, Shabestar, Sarab, Bostanabad, Bonab, Malekan, Ahar and Kaleibar). Plant samples were taken from flag leaf at anthesis stage, for 5 years (1999-2004). Following sample preparation, N, P, K, Fe, Mn, Zn, Cu and B concentration were analysed in Lab. At maturity stage, data of grain yield were collected in all relevant fields. The results showed that means of optimal N, P, K, Fe, Mn, Zn, Cu and B concentrations by DRIS and boundary lines were 2.46%, 0.23%, 1.74%, 137.9 mg. kg-1, 59.4 mg. kg-1, 16.7 mg. kg-1, 16.5 mg. kg-1 and 63.0 mg. kg-1, respectively. To use DRIS for irrigated wheat crop, data interpretation and studying of nutrient balance in plant, DRIS norms for 24 expression forms were defined. It can be concluded that expression forms for irrigated wheat crop in East Azarbayjan, except for B and Cu expression forms, can be used for deficiency diagnosis and studying of nutrient balance in plants.

Reactions of 74 promissing genotypes from temperate, cold, northorn warm and humid and Southern warm and dry agro-ecological senes together with a commercial check and a susceptible check were evaluated for their reactions to common bunt in Karaj and Kermanshah, during 2002-2004 growing seasons. Genotypes were evaluated under artificial inoculation using a randomized compelet block desigen with three replications. Mean percentage of infected spikes were analysed and genotypes were classified. Combined analysis of variance on mean percentage of infected spikes showed significant differences between genotypes in different agro ecological zones. Among temperate agro-ecological zone entries, commercial cultivar‘Pishtaz’ and two sister lines of ‘Alvand/MV17’ with 0.3, 0.9 and1.1percent infection, respectively, were resistant and Flt/Tajan’with 63.8% was the most susceptible genotypes, Bolani had 48.8% infected spikes. Among cold agro-ecological zone entries‘ K2340/Sx//Mt/Gb/3/K340‑/Fr/Pi/"S"/Kt54*//Nar"S"/5/1-32-1317//II/Y50E/3/Cno/Jar//On/4/Anza/3/Pi/ Nar/Hys with 0.5% infection was resistant.Commercial cultivar ‘Shahreiar’ with 33.7% infected spikes was susceptible and susceptible check had 63.7% infected spikes. Among nothern warm and humid Agro-ecological zone entries Chum/8/3Hel/3*Cno7g/2*Seri/4/Star with 10.1% infection was moderately susceptible and commercial check ’Tajan’ with 15.8% and susceptible check with 50.3% infected spikes were susceptible. Among Southern warm and dry agroecological zone entries Janz/Attila/4/San/Ald"S"//Avd/3/Kea"S"/Ghk"S" with 4.2% infected spikes was resistant. Commercial cultivar ‘Chamran’ and susceptible check with 17% and 58% infected spikes respectively, were susceptible. Considering that in commercial irrigated wheat cultivars resistant cultivars to common bunt are highly reguested in Iran, the resistant genotypes found in this study are very useful to be grown as cultivars or used as sources of resistance in wheat breeding programs.

Direct seeding of canola after summer crops has not proved to be suitable, because of low establishment. This experiment was carried out in order to compare of direct seeding and transplanting methods of canola hybrid Hayola 308 in Khuzestan agricultural research center during 2002 and 2003 cropping cycles. A strip plot arrangement in randomized complete block design was used, with 5 planting dates (Oct, 10 and 20, Nov.1, 10and 20) as horizontal plots and two direct seeding and transplanting methods as vertical plots. Means comparison showed that 40 days delay in sowing date lead to increasing of 3.5 days of sowing to germination interval and 11.4 and 33.0 days in flowering and maturity respectively. It also decreased pods per plants by 35.9, grains per pods by 2.7, grain yield to 1762.5 kg/ha and oil yield to 938 kg/ha. The transplanting method increased duration to flowering by 1.9 days, pods per plant 57.2 and grains per pod by 1.4, grain yield by 492 kg/ha and oil yield by 162.6 kg/ha. The interaction between sowing dates and planting methods showed that there are significant differences interactions between direct seeding and transplanting methods especially in late sowing dates. Considering economic yield, planting date of canola is recommended from Oct.10 to Nov. 1. Using transplanting method Nov. 10 until Nov. 20 would be suitable. In addition, transplanting method of canola is recommended for recovering the no or low established patches in the field.

To study the effect of the intensity and timing of topping on maize grain yield, an experiment was conducted for two years during 2002-2003 cropping seasons at Safiabad Agriculture Research Center (SARC) using KSC 704 maize hybrid. The experiment was carried out in factorial experiment using a Randomized Complete Block Design with four replications. Treatments were three levels of topping above the ear after anthesis (complete topping, one leaf left and two leaves left) and four topping dates (immediately after anthesis and three topping dates following anthesis with 10 days interval) and control treatment without topping. Results indicated that, there were significant differences among treatments for grain yield and 1000 kernels weight. Topping decreased grain yield and 1000 kernels weight. Control treatment had the highest grain yield (9.94 t/ha) and 1000 kernels weight (327.4 g), and complete topping treatment at anthesis had the lowest grain yield (8.15 t/ha) and 1000 kernels weight (269.79 g). Therefore, topping can decrease grain yield and 1000 kernels weight about 18 percent. There were no significant differences for protein content among treatments. The effect of topping and topping dates for forage yield was also significant. Complete topping with (6.57 t/ha) forge yield had the highest and two leaves with (2.63 t/ha) had the lowest level. Therefore, although topping produced about (6.57 t/ha) forage yield, however, reduced grain yields about (1.79 t/ha) or 18 percent, hence it is not recommended.

In order to determine critical period of weeds control in soybean a field experiment was carried out in Agricultural research station, Dashtenaz, Sari in 2003 cropping season. The experimental design was a complete Randomized block with 3 replications with 16 treatments. The treatment was included different stages without weeds, weeds competition during different plant phenological stages. The control treatment was weeds free and with weeds competition during growing season. Among recognized weeds species, Amaranthus retrofelexsus and Convolvulus arvensis had the maximum and minimum dry matter, at the rate of 47.2% and 2.3%, respectively. Weeds dry matter also decreased significantly with increasing weeds free period. The weeds free period did not significantly affect on the stem nodules, seed dry weight and the number of grain per pods. The maximum number of pods per plant (85) was recorded in the control plot (weeds free). The minimum number of pods per plant (40) was recorded in the control plot (with weeds competition during growing season). The number of unfilled pods per plant, biological yield, seed yield and the number of sub branches per plant decreased significantly with increasing the period of weed interference. Therefore seed yield (570g/m2) in the control plot (weeds free) decreased (185g/m2) in the control plot (with weeds competition). It can be concluded that significant decrease in grain yield can be prevented by control of weeds between phenological stages V3 (25days after seeding) and R1 (52days after seeding). The trends of variation of seed yield in comparison to the controls, in this period (V3 to R1) showed that it has decreased from 99.3 % in FR1 80.76 % in FV11 treatment and from 98.59% in CV3 to 72.2% in CV7.

In order to study effect of redroot pigweed (Amaranthus retroflexus L.) interference in sunflower, hybrid Hysun 33, a field experiment was carried out in the field research station of Islamic Azad University of Tabriz in 2004 cropping season. Three different pigweed densities of 5, 15 and 25 plants per meter of row and three time of emergence of 0, 15 and 30 days after sunflower emergence (DAE). The experiment of design was a randomized complete block with factorial arrangement and three replications. Emergence of sunflower and redroot pigweed seeds occurred after 4 days. Evaluated studied traits were stem height at the flowering stage, disc diameter, seed number in each disc, unfilled seed percentage, 1000 seeds weight, seed yield, oil percentage and oil yield. Analysis of variance indicated that difference between treatments due for studied traits were significant. The highest 1000 seeds weight (67.12g) and grain yield (3467kg ha-1) obtained from density of 5 plants m-1 in row and interference time of 30 DAE. Seed oil percentage in all treatments except three treatments including; first level of density at difference levels of interference time decreased in comparison with control treatment. The highest (1539kg ha-1) and the lowest (818.19 kg ha-1) seed oil yield obtained from density of 5 plants per meter in row and interference time of 30 DAE and density of 25 plants per meter in row and interference time of emerging with sunflower, respectively. It can be concluded that, redirect pigweed density has higher effect than its interference time on seed oil percentage and yield loss is more affected by interference time than by density.