نشریه نهال و بذر
سال نوزدهم شماره 2 (تابستان 1382)

Studying some important crop characteristics in a population and consideration of the limitations and possibilities, is a general way to determine the suitable genotypes. In this way, a part of population is used as a standard for evaluation of other parts and an optimal level is defined. In order to determine the optimal level in some crop characteristics and comparison of wheat suitability under dryland conditions, a broad information bank wasdeveloped and studied using results of 6 years cold-drylands yield trials. By using boundary lines, optimal level of crop characteristics including days to heading, days to physiological maturity, duration of grain filling, plant height and thousand kernel weight were determined, 221.2 days, 259.6 days, 33.8 days, 62.5 centimeter and 28.3 gram, respectively. These data were closely similar to the optimal levels obtained from averaging method. Results showed that recommended cultivars in each location had similar maximum crop properties balance index (CPBI). Related maximum CPBI in Maragheh, Sanandaj, Zanjan, Ardabil and Uromieh was about 155, 270, 150, 182 and 440, respectively. Comparing with the adaptability of some popular wheat cultivars showed that cv. Sardari is suitable for cold winter and cool spring with spring precipitation, Sabalan is suitable for cold winter and relatively temperate spring with abundant spring precipitation and Azar 2 is suitable for cold fall and mild spring with fall-spring precipitation and low winter precipitation.

Six male sterile with four male fertile sorghum, Sorghum bicolor(L.) Moench, lines were crossed in a factorial mating design in 1998. Twenty four F1 hybrids and ten parental lines were planted in a randomized complete block design in three replications, at Seed and Plant Improvement Institute, Karaj, Iran in 1999. Two cuttings forage were harvested from all genotypes (F12 and parents). Four traits including plant height, tiller no., green yield and dry matter were measured. There were significant differences among genotypes, cuttings and genotype X cutting interaction for all traits at 1% level of probability. Analysis of variance showed that, there are significant effects of genotypes, parent, parent vs. crosses (except for tiller no. at average of cuttings), lines (for plant height in 2nd cut and mean), testers and line tester interaction. There were differnces among lines and testers GCA which shows the importance of additive effects of genes for this traits, therefore, the selection methods can be used for breeding programmes. Heretiability of some traits were different in first, second and average of cuttings. Therefore, in each cutting, the heretiability should be considered in multi cutting sorghum lines. Significant differences were observed among SCA of some parents which shows the importance of dominance effects of genes for majority of traits in hybrids. Hence the hybridization method can be used for breeding programmes. The highest positive SVA was obtained for green fodder from crossing of A__ICS 84 × R__2 , A__ICS88005× R__1, A__ICS31×R__28 & A__1×R__112, and for dry matter from crossing of A__ICS88005×R__1, A__ICS__31×R__28, A__2×R__112, A__ISC84×R__112& A__ICS31× R__2 at average of two cutting. The highest yield of two cuttings was obtained for green fodder from crossing of A__ICS84×R__2 and for dry matter from crossing of A__ICS31×R__2 with 144.8 and 34.5 tha^-1 , respecticely.

In order to study the effects of different irrigation regimes and planting density on yield and agronomic traits of corn, an experiment was carried out in Research Farm of Orzoiyeh in kerman Agicultural Research Center for two years (1998-99). A split-splite plot randomized complete block design with 18 treatments and four replications were used. The irrigation treatments were assigned to main plots(irrigation after 75 mm irrigation after 100 mm irrigation after 125 mm, from class A pan). Row spaces were assigned to sub plot(60 and 75 cm) and plant spaces to sub-sub plot (15, 20 and 25 cm). Results showed that the grain yield among irrigation regimes, row spacing and plant spacing were significantly different. Among irrigation regimes, treatment of irrigation after 75 mm had the highest and treatment of irrigation after 125 mm had the lowest grain yield. By increasing the planting density, kernel/ ear, ear length and kernel protein percent decreased, but grain yield increased. Highest grain yield obtained in 111100 and 88800 plant/ha, respectively. The effect of irrigation regimes and planting density (row space and plant space) on harvest index was not significant, and this index was about, 52%. In this study water use efficiency increased with increase in planting density and water stresses. Based on the results of this study, the second irrigation regime for period of the first three months and the third irragation regime for the last month of corn growth period and planting density of 88 and 111 thousand plants per hectare, (combinations of 75 × 15 and 60× 15 cm) could be recommended for Orzoiyeh region.

In order to study the effects of four tillage systems on yield components of three soybean cultivars, an experiment was conducted in a field at Araghi -Mahalleh Research Station of Gorgan in summer of 1997, after wheat was harvested. The experiment was factorial based on a randomized complete block design with four replications and 12 treatments. Treatments ware the combinations of four tillage systems and soybean cultivars. The tillage systems were T__1) burning wheat straw two perpendicular disks irrigation a shallow disk planting, T__2) burning wheat straw irrigation direct drilling (no-tillage), T__3) two perpendicular disks on the field consisting of wheat straw irrigation planting and T__4) irrigation direct drilling on the field having wheat straw (no-tillage). The three soybean cultivars used in the experiment were williams, Gorgan 3, and Sahar. Characteristics such as number of days from sowing to flowering and maturity, number of seeds per pod, number of pods plant, number of seeds per plant, 1000 seeds weight, and grain yield were measured. The results indicated that the T__3 and T__4 tillage systems increased number of days flowering and maturity, 1000 seeds weight, and grain yield, compared to the other systems. However, there was no significant difference among four systems in number of seeds per pod. The number of days from sowing to flowering and maturity and number of pods per plant in sahar cultivar were higher than those of the other two cultivars. The highest grain yield was obtained from sahar cultivar under T__4 tillage system. In this experiment, 1000 seed weight was the only component that showed significant positive correlation coefficient with the grain yield.

In this study 58 isolates of Fusarium moniliforme which causes rice foot rot disease were collected from infected rice seeds. The morphological characteristics and pathogenicity of these isolates were determined in laboratory and greenhouse in the International Rice Research Institute (IRRI). Besides, by RAPD(Random Amplified Polymorphic DNA) technique using primer J-11 from operon kit by sequences of "5-ACTCCTGCGA-3" the randomized portion of the DNA of each isolate was amplified. Using cluster analysis at 25% similarities, the isolates were classified as follows: from point of the growth rate of fungi after 4 days in Petri dishes into 8 groups from point of the number of days that fungi reached to the 90 mm diameter in one group from point of the effect of isolates on the length of seedlings into 5 groups from point of the genetical pattern into 13 groups. The characteristics measured in the laboratory or greehouse for each isolate did not significantly differ with the mean of each group using t-test analysis. Therefore, it could be concluded that molecular markers by RAPD technique can be used in differentiation of morpological and pathogenicity of Fusarium moniliforme isolates. The positive significant correlation coefficient (r=0.54) was observed between the growth rate of fungi in petri dishes and its effect on the length of seedling.

The rate of sensitivity of nymphs and adults of Eurygaster integriceps put., fed on wheat cultivar falat, to fenitrothion insecticide was studied. The main objective of this study was to determine the possibility of integrating wheat cultivars with fenitrothion in an integrated sunn pest(E. integriceps) management programme. The experiments were conducted in laboratory and field in varamin during 1998-9 The sensitivity of 4th and 5th instar nymphs and new adults reared on falat to insecticide fenitrothion (a.i=50%) was enhanced, compared with those on sardari. LC50 of insecticide on all three life stages of insects fed on falat was less than sardari. The LC50 of insecticide on all three life stages of insects fed on falat was less than sardari. The LC50 of insecticide on sardari and falat for 4th instar nymphs was 42.16 and 33.48, for 5th instar nymphs was 147.03 and 114.01 and for new adults was 303.35 and 227.88 ppm, respectively. Therefore LC50 of insecticide for 4th and 5th nymphs and new adults fed on falat was reduced about 20,22 and 25 percent, respectively, compared with those on sardari. The results also showed that by increasing the life stages of insects reared on falat, the rate of sensitivity to insecticide was enhanced. The comparison of MRGR for 4th and 5th instars reared on falat and sardari with and without using sublethal doses of insecticide showed that there was synergism between falat and fenitrothion. sardari/falat ratio of MRGR with and without using insecticide for 4th nymphs was 1.53 and 1.23 and for 5th nymphs was 2.02 and 1.34, respectively.

To study the stability and adaptability of grain yield of advanced bread wheat genotypes in cold and moderate-cold dryland areas, 16 adanced genotypes were evaluated in Maragheh, sararood, kordestan, Ilam, Zanjan, Shirvan, Orumieh and Ardebil Experimental Stations in 1998 to 2001 cropping seasons. The experimental design in all the locations was randomized complete block design with four replications. In each location simple and combined analysis of variance were implemented. Based on homogeneity of error variances, combined analysis of variance was done over locations and years. Results showed that interaction effect of genotype × year × location was significatn at 1% probability level. A significant difference was also found among the genotypes, and genotypes No. 4(Azar 2) and No. 10(sbn/ 1-64-199) with 1635 and 1597 kgha^-1produced the highest the highest grain yield respectively, sardari(the check cultivar) produced 1485 kgha^-1 of grain yield. Result of stability analysis on grain yield using parametric method of C.V.% and Lin and Binns, and non-parametric method of rank, showed that genotypes No. 4(Azar 2) No. 16(Sardari) and No. 10(Sbn/1-64-199) were the most stable genotypes. Overall based on the mean of grain yield, stability parameters and diseases results, genotype No. 10(Sbn/ 1-64-199) was found to be the highest yielding, most stable and resistant to yellow rust genotype, therefore it was selected as a desirable genotype.

In cold regions, for successful wheat production close attention must be paid to all factors that influence a plant ability to attain maximum winterhardiness and grain yield. In this study the effects of sowing depths on grain yield and winter survival of winter bread wheat (Triticum aestivum L.) was studied in cold regions of Ardabil. An experiment was set up in a randomized block design with four sowing depth treatments (4, 7, 10 and 13 cm) in three replications for two years(1992-93). The results showed that the grain yield was significantly (P < 0.01) differed. The highest yield and less winterkill were obtained from shallow seeding treatment (4 cm). Increases in seeding depth resulted in significantly (P < 0.01) low yield and high winterkill. The relationship between grain yield (Y) and sowing depths was described by a polynomial equation: Y=1.808-158.5X+5.523X__2 where this curve accounted for 91% observed variation in grain yield. It can be concluded that in cold regions of Ardabil, shallow planting compared to deep planting can increase grain yield and minimize winterkilling of winter wheat cultivars.