Iranian Journal of Crop Sciences
Year:2003 | Volume:5 | Issue:4|Papers Count:10

In order to determinate critical levels of Fe, Mn, Zn, Cu and B micronutrients for dryland wheat in Western Azarbayejan, Eastern Azarbayejan, Kurdestan and Kermanshah dryland areas, experiments were conducted using RCBD design with 4 treatments (including control) and three replications for each micronutrients in four years (1998-2002). The total number of sites for Fe, Mn, Zn, Cu and B were 26, 25, 27, 26 and 17, respectively. Fe fertilizer rates were used 0,5, 10 and 15 kg.ha-1 from iron chelate (NaFeEDDHA); Mn and In fertilizer rates were used, 0, 5, 10 and 15 kg.ha-1 from Manganese Sulfate and linc Sulfate sources, respectively. Cu fertilizer rates were used 0, 2.5, 5 and 7.5 kg.ha-1 from Copper Sulfate; and B fertilizer rates were used 0, 1.5,3 and 4.5 kg.ha-1 from Boric Acid sources. Crop and soil data uniformity were tested for experimental sites. Data were used to fit best models for soil testing data and relative grain yield responses for each micronutrient. Results showed that for cation micronutrients, the best model was Mitshcherlich equation. In this model, Fe, Mn, Zn and Cu the critical levels for obtaining 90% of maximum grain yield were 8.8, 11.3, 0.88 and 1.8 mg.kg-1 in soil, respectively. For the anion B critical level was determined 0.65 mg.kg-1 insoil. It is concluded that Fe, Mn, Zn, Cu and B, critical levels in soils of drylands in the North-west of Iran can be used to determine research priorities as well as fertilizers management and applications.      

Evaluation of inbred lines and their combining ability is one of the most important and expensive stages in hybrid seed production, by which superior parents and crosses can be identified. Diallel crosses is common and effective method to determine combining ability. In most of studies combining ability has been estimated in one environment. The present investigation carried out to study the effect of environments on combining ability estimation of different characteristics/ traits of rapeseed (Brassica napus L.). In this study 7 rapeseed inbred lines randomly selected and crossed in all combinations (including reciprocals) in 1999. Parents and crosses were evaluated in 2000 (environment no.1) and 2001 in two sowing dates (environments no.2 and 3) in RCBD with 2 replications. Twenty one agronomic and oil quality characteristics/ traits measured in parents and hybrids. Pooled combining ability analysis showed that general combinig ability (GCA) of parents was significant for all characteristics/ traits except Stearic acid. Specific combining ability (SCA) of hybrids was also significant for all characteristics/ traits. These results revealed that both additive and dominant (non-additive) gene action was important for these characteristics/ traits. The GCA × environment interaction was significant for all characteristics/ traits except Stearic acid. The SCA × environment infraction was also significant for all characteristics/ traits. It showed that combining ability of parents and hybrids were different from one environment to another. Estimation of combining ability effects also was not similar in different environments. Sometimes differences were high as they changed from positive to negative or vice versa. There were 11 cases in estimation of GCA effect and 44 cases in estimation of SCA effect that the sign of estimations were changed and the differences were significant. In other hand estimation of combining ability effects by pooled data analysis showed better results. Mean performance of characteristics/ traits in parents and hybrids were not similar in different environments. Selection of superior parents and hybrids should be carried out according to mean performance and combining ability, hence selection by one year in one environment is risky and may lead to undesirable results. Therefore, selection on the basis of multi-environment is recommended.        

This study was carried out in order to determine yield, and other traits in Champa rice cv. Kohrang as affected by seeding rate, planting date in the nursery and date of transplanting in Lordegan region in 2000 and 2001. The experimental design was split plot with 3 replications. The main plot included date of transplanting. The combination of two other factors, seeding rates and planting dates (factorial) was assigned to the sub plots. The rates of seeding were 60, 80 and 100 kg/ha. Different planting dates in the nursery were 21 April, 30 April and 10 May 2000 and 2001 cropping season. Transplanting was carried out in 8, 18 and 28 June in 2000 and 2001 cropping seasons. Results indicated that there was no significant difference between years for paddy yield, but the difference between seeding rates was 80 kg/ha. The effect of planting date in the nursery was highly significant (p < 0.01) and the maximum yield was produced in the second planting date (30 April). The effect of transplanting date was also highly significant (p < 0.01). The best transplanting date was 18 June, with paddy yield of 5840 kg/ha. Growing Degree Days (GDD) and days to 50% flowering reduced with delay in planting date in nursery, it increased with late transplanting date. The effects of seeding rates on yield components were low, however, planting date in nursery and transplanting date had greater effects on this characteristics.      

Seven homozygous wheat lines representing different levels of resistance to Fusarium head blight were evaluated under infection and normal conditions in a field experiment at Gholestan Province during 2001. Under infected condition, disease incidence (DI), disease severity (DS), disease index (DIX), area, under the disease progress curve (AUDPC), grain yield and its components, while under non-infected condition only grain yield and its components were recorded. Genotype as well as genotype × environment interaction effects was significant for all the studied indices. Mean comparisons revealed heterogenous trend in responses to infection measured by the different indices. Disease index (DIX) and its AUDPC could not differentiate susceptible from moderately susceptible and resistant from moderately resistant lines. Grain yield and number of kemels per spike had similar shortcomings as DI and its AUDPC. In general, considering all parameters, 1000 grain weight, DS and its AUDPC were regarded as better indices to differentiate resistant from susceptible lines and to recognize different types of resistance.      

To determine the critical period of weed competition and adequate time for weed control an experiment was conducted with two factors including maize varieties (SC-704 and SC-604) and weeding times (12 times of hand weeding) in Kermanshah province in 1999 cropping season. The weeding times were divided into two sets; including weed interference util 0, 2, 5, 10 leaf stages, tasling and silking stages and weed removal at these stages. These two sets of data were analysed and Logistic and Gompertz equations were fitted, respectively. With a 5% yield reduction tolerance, SC-704 had a critical period of 5-8 leaves stages (26-37 days after emergence) for grain yield and a period of 4-12 leaves stages (23-47 DAE) for dry mass. In SC-604 the critical periods for grain yield and dry mass were 3-9.5 leaves stages (20-41 DAE) and 2-13 leaves stages (17-51 DAE), respectively. Based on accumulated degree days (GDD), the critical period of weed competition for grain yield and dry mass in SC-704 and SC-604 were 318-471 and 286-644 and 256-556 and 206-676 GDD, respectively. Wild Licorice (Glycyrrhiza lepidota), field Bindweed (Convulvulus arvensis) and Common purslane (Portulaca oleracea) were the dominant weeds in the early growing season, while Johnsongrass (Sorghum halepense) and Camelhom (Alhagi camelorum) were dominant at the end of the growing season. The number of weeds and its dry weight in weed free treatment decreased by 75 and 81% in comparison with control for 35 days after crop emergence. The whole season weed interference with maize reduced the yield and dry mass by 80 and 86% of weed free control.      

The present investigation was carried out to determine efficiency of in vitro bioreactor-based tuberization of potato. In vitro potato stock plants (Solanum tuberosum L. CV. Agria) were obtained from apical meristems followed by thermotherapy. These in vitro plants were multiplicated by serial subcultures in 300 ml jars containing MS liquid medium. Cultures were incubated under 24/22 °C day/night temperature regime with a 16- h photoperiod fluorescent light at an irradiance of 3000 lux (36 µmol m-2 S-1).Multiplication medium consisted of MS Salts and Vitamins, 30 gL-1 Sucrose, 2 mgL-1 6-Benzylaminopurine (BAP), 0.1 mgL-1 Naphthalene Acetic Acid (NAA) and 1.0 mgL-1 Gibberellic Acid (GA3). Tuber induction medium was the same as basal medium except 80 g L-1 sucrose, and 7 mg L-1 BAP were used. Shoots produced in a 300ml jar were transplanted into a 3L bioreactor vessel and the medium was pumped into it every 8 hrs. to immerse the shoots for about 30 minutes. The entire medium was changed with tuber induction liquid medium after 4 weeks. These cultures were incubated under continuous dark condition at 20 °C for 4 weeks. The growing shoots were subcultured from 300 ml jar to bioreactor in which they continue to grow. After 3 days tuber induction was observed. The tuberization occurred mainly at middle part of the bioreactbr. The total number, of microtubers in this 3L bioreactor was about 550 and was very more efficient than routine system (3 to 4 microtubers per 300 ml jar).      

This study was conducted to evaluate the effects of herbicide application and plant density on weeds population in broad bean crop which cause significant yield loss at the Safi Abad Agricultural Research Center, Dezful, Iran from 1999 to 2001. The experimental design was a randomized complete block design with stripe plot arrangement of treatments and three replications. Row spacing was as vertical factor consisting of 45, 55 and 65 cm, plant spacing within row was as horizontal factor consisting of 10, 20 and 30 cm. Herbicide treatments were as sub-plots consisting preemergence application of Chlorthal Dimethyl at 7.5 and 9 kg ai/ha, post emergence application of Bentazon at 0.75 and 1 kg ai/ha plus Haloxyfop Ethoxy Ethyl at 0.25 kg ai/ha, weed free and weedy Control. Chenopodium murale L. , Malva sylvestris L. and Sinapis arvensis L. and total number of weeds were controlled and dry weight of weeds were reduced by all herbicide treatments in 1999. Beta maritima L., Malva sylvestris L. and total number of weeds were controlled and dry weight of weeds were also reduced by all herbicide treatments in 2000. In comparison to the weedy Control, application of Chlorthal Dimethyl at 7.5 and 9 kg ai/ha, Bentazon at 0.75 and 1 kg ai/ha plus Haloxyfop Ethoxy Ethyl at 0.25 kg ai/ha and weed free Control increased broad bean seed yield by 192, 156, 453, 457 and 480% in 2000 and by 28, 34, 24, 47 and 48% in 2001, respectively. Row spacings of 45 and 65 cm with 3065 and 2292 kg/ha had the highest and lowest level of broad bean yield respectively. In zoag plant spacing within row of 10 and 30 cm with 2631 and 1989 kg/ha had also the highest and lowest yield, respectively. However, in 2001, plant spacing within row of 20 and 30 cm with 3781 and 2466 t/ha had the highest and lowest yield, respectively. Post-emergence application of Bentazon at 0.75 or 1 kg ai/ha plus Haloxyfop Ethoxy Ethyl at 0.25 kg ai/ha or pre-emergence application of Chlorthal Dimethyl at 7.5 or 9 kg ai/ha or two hand weedings at 5 and 11 weeks after planting, row spacing of 45 cm and plant spacings within row of 10 or 20 cm are recommended for  effective weed control and grain yield increase in broad bean fields under safiabad, Dezful conditions.