فصلنامه علوم زراعی ایران
سال ششم شماره 1 (پیاپی 21، بهار 1383)

The susceptibility of 52 wheat and 12 barley cultivars to two pathovares of cereal’s bacterial leaf streak (BLS) was studied. The experiment was carried out under field conditions. Seeds of all cultivars were grown using randomized block design with 4 replications in the Alborz Research Institute, Karaj in 1999-2000 cropping season. In spring of 2000, 20 days after inoculation of seedlings with a suspension of bacteria (adjusted approximately to 109 cfu/ml) the percentage of infected area on the lower leaves were scored from %1 to %75 in 5 levels. Results showed that among wheat cultivars, Kavkaz, P.K., Sardari, Adle and Golestan were more susceptible and Kaveh, Mahooti, Maroon, Shiroudi, Chenab, Niknejad, Bayat, Moghan 1, Morocco, Cross Azadi, Alborz, Hirmand and Arvand cultivars showed resistant reactions to BLS. In barley cultivars Zarjo, Karoon, Dasht, Goharjo, were more susceptible and. Aras, Eram and Valfajr were more resistant.

In this study three sugar beet genotypes were selected based on some physiological and agronomical characteristics and had determined to be resistant, semi resistant and sensitive to salt were studied to identify relationship between physiological indices and organic compositions and the best method for determining tolerance and sensitive gonetic resources in laborary and field conditions studying percentage of germination, initially seeds were planted in different osmtic pressure that were provided by mannitol solution and compared for seedling stability, and germination stability using randomized complete block design with two replications, and were grouped according to fisher and maurer index to tolerance, semi tolerance and sensitive. According to this grouping, tolerant genotypes had higher seedling stability and germination than semi- tolerant and sensitive genotype. These genotypes were also tested under natural salt stress of soil in Amir abad, Karaj. In comparison of genotypes for synthesis of proline, leaf soluable proteins, cytoplasmic membran stability, there was no direct significant relationship between accumulation of proline and relative tolerance of sugar beet. Tolerant genotypes had higher cytoplasmic membrane stability and relative water content than other genotypes. Chlorophyl a had a significant and positive correlation with root yield. It was concluded that chloryphyll b has no requirement to salt stress for synthesis and is not under effect of this stress. In study of leaf soluable proteins, genotypes were classified in separated groups. Positive correlation of this character with relative water content and root yield shows that this character can be used as selection index for salt tolerance in sugar beet breeding programs.

In this study, a rhizomania resistant wild beet accession, Beta. vulgaris subsp. maritime, WB42 was crossed in pairs with susceptible male-strile lines, Beta. vulgaris subsp. vulgaris and F1, F2 and BC1 populations were obtained. Hypocotyl and flowering stem pigmentation of WB42 were red and those of the susceptible lines were green. Segregation ratio of hypocotyl and flowering stem pigmentation and resistance to rhizomania genes as well as RAPD markers were assessed in segregating populations. No segregation distortion were observed for the genes controlling hypocotyl and flowering stem pigmentation and resistance to rhizomania, in segregating populations. The segregation distortion for RAPD markers in this crosses were lower than the B. vulgaris  B. vulgaris cross. It is concluded that the genetic background of B. v. subsp. maritima doesn’t influence the amount of the segregation distortion in B. v. subsp vulgaris  B. v. subsp. maritima crosses.

To study the effect of inoculation of soybean cultivars with different strains of Bradyrhizobium japonicum for determining the best bacteria-cultivar combination, an expriment was conducted using split plot design with 3 replications in 2001 cropping season at seed and plent Improvement Institute, Karaj, Iran. The other experiment was carried out using randomized complete block design in the green house. The factors student were two cultivars of soybean (Williams and Line L11) and four bacterial strains of Bradyrhizobium japonicum including Helinitro, Highstick, Soyar and SWRI and a control plot (without bacteria). Characteristics such as number and weight of nodules per plant, weight of plant dry matter at harvest stage and shoot/root per plant and percentage of nitrogen in the soil as well as the amounts of nitrogen in plant shoot: with N-difference method were measured and recorded. The results showed that Highstick could fix more nitrogen than other strains. In the other hand, cultivar L11 had better symbiotic activity than cultivar Williams and fixed higher amount of nitrogen. Highstick and L11, in most characters, found to be the best combination.

In order to evaluate the different photoperiod and temperature sensitive pre-flowering phases in two cumin landraces a raciprocal transfer experiment from photoperiod 8 h to 16 h and vice versa under two different day/ night temperatures 20/10 and 30/20 ˚C was conducted. Two model including Ellis and Adams were used to analyse the data and to quantify the duration of different developmental phases. The results indicated a high probability for variation in phototermal responses among the cumin landraces of Iran. It was found that photoperiod sensitivity in Azarshahr is greater than Mashhad landrace. In addition it was found that temperature affects on the timing of different developmental phases. This is one of the main causes of errors in phonological models. Different behavior of temperature sensitive and insensitive phases provides the possibility of testing the hypothesis about the role of different gene groups in general developmental procsess. It was clear that the temperature sensitivity for photoperiod genes of Azarshahr landrace is higher than Mashhad landrace. These results would contribute to better understanding of variation in photoperiod and temperature sensivity in cumin as well as optimization of phonological models.

Improper sowing date and competition of weeds are the most important constraints in lentil production in Iran. In order to study the effect of sowing date and single and integrated application of herbicides, an experiment was conducted using complete randomized block design in a split plot arrangement with four replications at field station of Tehran University, Karaj (Iran) during 2001-2002 cropping season. Treatments comprised of two date of sowing winter and spring sowing as main plots and eleven weed control methods as sub plots. Weed control treatments were included a pre-emergence application of Cyanazin, post-emergence application of Pyridate and Oxyflourfen, different combination of a pre-plant application of Trifluralin; Pendimethalin each with post–emergence application of Pyridate and Oxyflourfen plus one handweeding; and finally a weed free and infested plot as controls. Amaranthus lividus L. and Chenopodium album L. were the predominant weeds. Xanthium brasilicum Vellozo, Convolvulus arvensis L., Solanum nigrum L., Melilotus officinalis L., Veronica persica Poir and Polygonum aviculare L. were of less importance. Combination of pre-plant application of herbicides with hand weeding or post- emergrnce application effectively controlled weeds. The combined treatments of Pendimethalin + one handweeding, Trifluralin + one hand weeding and Pendimethalin + Pyridate showed the best results. These treatments effectively controled total broadleaf weeds by 93, 88 and 85 percent, respectively. It was concluded that these treatments are the best for weeds control in lentil crop under coditions similar to those of this experiment.

In order to evaluate the early vigour (early season dry matter accumulation) of cotton (Gossypium hirsutum L.) seedlings, two field and laboratory studies were conducted in 2001 cropping season. In this research, 12 cultivars with determinate (Oultan, No-228 and Lamberaite), semi- determinate (Shirpine, Shirpine 603 and Shirpine 533) and indeterminate growth habits with normal leaf shape (Deltapine 50, Zeta 2 and 1097) and Okra leaf shapes (Red leaf Okra, Super Okra and Okra) were studied in a randomized complete block design with 4 replications. Cultivars with the greater seedling dry matter in the field experiment (44 days after planting) were selected and some of their morphological and physiological characteristics were evaluated in both field and laboratory studies. These selected cultivars were Oultan (from the determinate cultivars), Shirpine 603 (from the semi-determinate cultivars), Deltapine 50 (from the indeterminate cultivars with normal leaf shape) and red leaf Okra (from the indeterminate cultivars with Okra leaf shape). The results of the field study showed that red leaf Okra and Shirpine 603 had the highest and lowest dry matter, hence early vigor, respectively (P<%5). Although there was no significant differences between Leaf Area Index (LAI) of Oultan and red leaf Okra, the Crop Growth Rate (CGR) of red leaf Okra was the greatest among all four cultivars, it had also the highest Net Assimilation Rate (NAR). Deltapine 50 had the highest mean of Leaf Area Ratio (LAR) and Leaf Weight Ratio (LWR) but it could not produce high dry matter, because its LAI and NAR were low. The results of the laboratory study showed that red leaf Okra could produce the highest seedling dry matter at twelve days after sowing in incubator and had the greatest seed reserve utilization efficiency and germination capacity (P<%5). The highest correlation coefficient was observed between dry matter production with maximum Relative Growth Rate (r= 0.99**) in the field and with coleoptile dry matter (r= 0.99**) in the laboratory.