Journal of Crop Production and Processing

---

A total of forty-three isolates of Ascochyta rabiei obtained from infected seeds and plants of chickpea from different areas of Kermanshah, Lorestan, Hamadan, Kordestan, and East and West Azarbaijan provinces were studied during the period 1996-1999. A rapid and simple method was developed for pathogenicity test in CDA (chickpea seed meal dextrose agar) medium. CDA medium was inoculated with different isolates and incubated at 21±1 ^oC for 9 days. The disease severity was scored as 0-100% at 24-hour intervals up to five days. Virulence forms were designated according to spectrum of disease reactions of each isolate. Thirteen isolates (IK04, IK08, IK10, IK13, IK14, IK17, IK19, IK21, IL01, IL10, IO00, IE04, IE06) were distinguished as highly virulent (HV) and 7 isolates (IK03, IK06, IK15, IE01, IE08, IL04, IL06) as weakly virulent (WV). Polygalacturonase activity of these isolates from 6 days old inoculated PZ (pectin zymogram) medium were assayed. Comparison of the results of pathogenicity test and PG activity of 43 isolates demonstrated that HV isolates show predominant enzyme activity while the WV isolates show enzyme activity.

---

Watermelon (Citrullus Lanatus) cv. Charleston Gray is one of the most important cultivars grown in Iran. It has some good quantitative and qualitative characteristics but unfortunately is sensitive to Blossom End rot. To solve this problem, this experiment was conducted in a factorial manner in randomized complete block design with four replications in Research Station and Laboratories of Department of Horticulture, College of Agriculture, the University of Tehran, during 1997 & 1998. In this experiment, black polyethylene mulch was used and calcium nitrate was foliar sprayed at concentrations of 0, 4, and 6 g/L. Results indicated that mulch could increase yield by 85% over two years due to weed growth suppression and conserving soil moisture for a longer time. Foliage fresh weight, number and average weight of fruits per plant and precocity were also significantly affected by black polyethylene mulch. Furthermore, mulch reduced the number and weight of fruits affected by Blossom End rot by about 13% and 12.5% (average of two years), respectively. Calcium nitrate addition during both years had no significant effect on the measured fruit characteristics nor on Blossom End rot.

---

---

Plant pathogenic microorganisms produce a variety of enzymes capable of degrading different polysaccharides of the plant cell walls. Pathogens use these enzymes to penetrate and colonize host cells. Polygalacturonases are thought to be the first cell wall-degrading enzymes secreted by pathogens when they grow on plant cell walls. Oligogalacturonic acids with the polymerization degrees of 10 to 13 are intermediate products of pectin degradation by the action of polygalacturonases and are known to activate plant defense responses. PG- inhibiting proteins (PGIPs) present in the cell wall of many plants increase the stability of oligogalacturonic acids in the tissues by modulating fungal PG activities. These glycoproteins of the plant cell extracellular matrix retard the advancement of fungal hyphae, reduce tissue maceration, and prevent colonization of pathogen. In this study, Phaseolus vulgaris PGIPs were extracted from hypocotyle of Derakhshan and Naz bean cultivars. PvPGIPs were purified by afinity chromatography and analyzed by SDS-PAGE. Three major bands in the range of 47-55 kDa were detected. Average yield of The affinity-purified PGIPs was 1.68 mg per 100 gram of fresh bean hypocotyle. The inhibitory effect of PGIP was assayed on the PG activities of highly virulent isolates of Fusarium oxysporum (F15) and Ascochyta rabiei (IK04). The inhibitory activity of crude PGIP from Naz and Derakhshan cultivars on polygalacturonase activity of F. oxysporum was 18 and 28 units, respectively. These inhibitory activities increased to 40 units after purification. The inhibitory effect of crude PGIPs from both these two cultivars on PG activity of A. rabiei was 9 units, while purified PGIPs inhibited this PG activity to 18 and 29 units, respectively.

---

The genetic diversity of major crops, including durum wheat, has suffered an overall reduction with time. The knowledge of patterns of genetic diversity enhances the efficiency of germplasm conservation and improvement. In this study, 87 Iranian landraces of Triticum turgidum var. durum originating from different geographical areas of Iran, along with 21 durum cultivars from ten countries were evaluated using ten primer combination SSAP markers. Retrotransposons are mobile genetic elements that transpose via RNA mediation. They have wide distributions in genome because molecular markers have been designed based on them in recent years. SSAP markers BARE-1,Thv19, Tagermina and Tar1 were also used. Thv19M+ACA primer combination had the most polymorphic band in both landraces and cultivar durum wheats. Approximately 26.7 % BARE-1 bands were polymorphic in landraces.Thv19 showed a polymorphism level of 51.5%, and Tar1 and Tagermina displayed polymorphism levels of 32.8% and 27.2%, respectively. The amount of polymorphism in the studied cultivars for retrotransposons BARE1, Tagermina, Thv19 and Tar1 were 24.4%, 24.3%, 51.5%, 28.5%, respectively. This results show that Thv19 and Tar1 have more transpositional activity in the evolutionary process. Finally, Dendrogram was constructed to use algorithm UPGMA and Dice similarity coefficients.

---

Fusarium head blight (FHB) is one of the most destructive diseases of wheat causing significant reduction in grain yield and quality. Development of resistant varieties is an effective, economical and enviromentally safe way to control FHB disease. A major QTL (quantitative trait locus) for Fusarium head blight resistance, Qfhs.ndsu-3BS, derived from cv. Sumai 3, has been identified and verified by several research groups via molecular marker analysis. The resistant cv. Sumai 3 was crossed to susceptible cv. Falat, then three backcrosses were followed by one self-fertilization. Three simple sequence repeat (SSR) markers, Xgwm 389, Xgwm493, Xgwm533, were used for marker assisted selection (MAS) in BC1 and BC2 generations.The probability of linkage between markers and Qfhs.ndsu-3BS was calculated using a binomial probability function based on the assumption that a molecular marker at a specific distance from Qfhs.ndsu-3BS in the population would carry the donor-parent allel as a function of the distance between marker and QTL and the number of backcrosses/selfs used in deriving the population. Microsatelite locus Xgwm 493 was significantly associated with Qfhs.ndsu-3BS.