p. 359−367
2783-5383
Vol.30/No.3
p. 368−378
2783-5383
Vol.30/No.3
p. 379−387
2783-5383
Vol.30/No.3
p. 388−395
2783-5383
Vol.30/No.3
p. 396−406
2783-5383
Vol.30/No.3
p. 407−415
2783-5383
Vol.30/No.3
p. 416−425
2783-5383
Vol.30/No.3
p. 426−440
2783-5383
Vol.30/No.3
p. 441−448
2783-5383
Vol.30/No.3
p. 449−459
2783-5383
Vol.30/No.3
90% of world production), G. barbadense (3-4%), G. arboreum and G. herbaceum (together, 2%). Cotton is grown as a cash crop; it is often grown in a monoculture system that favors the development of a nematode community dominated by one or a few parasitic species. The different genera of plant parasitic nematodes such as Haplolaimus, Helicotylenchus, Blanolaimus, Pratylenchus, Paratrichodorus, Meloidogyne, Merlinius, Xiphinema, Tylenchorynchus, Rotylenchulus, Scutellonema, Heterodera, Ditylenchus, Longidorus, Aphelenchoides, Aphelenchus were recorded from cotton fields in the world. The objective of this study was to investigate the plant parasitic nematodes associated with cotton fields in Southern Khorasan province of Iran.
Materials and Methods: In order to identify the plant parasitic nematodes in cotton fields in Southern Khorasan province, 56 soil samples were collected from different areas during 2013 and 2014. Soil samples were washed and nematodes were extracted by combined sieving and centrifugal-flotation method of Jenkins (1964) and Whitehead tray method (1965). Nematodes were fixed and transferred to glycerin by using the method of De Grisse (1969). The permanent slides were prepared and the nematodes were studied by light microscope.
Results and Discussion: In this study, 15 species from 10 genera related to order Tylenchomorpha, were identified as follows: Aphelenchus avenae, Basiria graminophila, Boleodorus clavicaudatus, B. pakistanensis, B. thylactus, Ditylenchus hexaglyphus, D. tenuidens, D. valveus, Geocenamus rugosus, Filenchus vulgaris, Pratylenchus neglectus, P. thornei, Scutylenchus quadrifer, Merlinius brevidens, Zygotylenchus guevarai. One genus of cotton-parasitic nematodes known to cause yield loss were found in this survey (Pratylenchus spp). Other parasitic nematodes not known to cause yield loss also were found. Three species, including Boleodorus pakistanensis, Ditylenchus hexaglyphus, D. valveus are reported as new records for Iran. Boleodorus pakistanensis is characterized by four incisures, head low, unstriated and conoid shape, stylet 8.5-10µm with cone short and slender knobs, non-muscular median bulb, Basal bulb pyriform, posterior vulva (v=68.1-72.4 ; v/=77.5-88.4). Tail elongate-conoid, central arcuate, ending in a finely rounded terminus. B. pakistanensis resembles, B. flexuosus B. teres, B. thylactus and B. cylindricus. B. thylactus but can be differentiated by the more posterior position of the opening of the dorsal gland (2 vs 3-5); B. flexuosus has a more anterior vulva (V=54-63 vs 68.1-72.4); B. teres has a more anterior vulva (V=54-63 vs 68.1-72.4), tail shape and stylet length (10-12 vs 8.5-10); B. cylindricus has a more anterior position of the opening of the dorsal gland (7 vs 3-5) and more tail (88-101 vs 72-88.5). Ditylenchus hexaglyphus is characterized by six lines in lateral fields, low head, stylet 8-9µm with cone shorter than the shaft and small elongated knobs, non-muscular median bulb, Posterior bulb offset, posterior vulva (v=82.3 -83.5; v/=87.8-89.6). Tail ventrally curved, terminus rounded. Having non-muscular median bulb, six incisures, short stylet and posterior vulva. D. hexaglyphus resembles D .medians, D. taylori, D. affinis, and D. tuberosus. However, none of these species have such small stylet knobs, and all but D. affinis have longer PUS than that observed in D. hexaglyphus. D. taylori more anterior vulva (V=75-77 vs 82.3-83.5) and tail appears to be thinner (c/=6-7 vs 2.9-3.8); D. affinis has a more anterior vulva (V=76-80 vs 82.3-83.5). Ditylenchus valveus is characterized by six incisures, annulated head, stylet 8-9µm with short cone and small rounded knobs, muscular median bulb with small. Posterior bulb offset, posterior vulva (v=74.3 -81.5; v/=84.9-89.2). Tail terminus rounded. Because of six incisures, short stylet, vulva position, oesophagus structure and tail shape, D. valveus resembles D. acutatus D. myceliophagus and D. medicaginis. D. myceliophagus differs from D.valveus by tail shape and generally overlapping oesophagus; D. medicaginis differs from D. valveus mainly by tail shape and also slightly more posterior vulva position (78-83 vs 74.3-81.5); D. acutatus differs from D. valveus mainly by tail shape.
Conclusion: In this study, 15 species from 10 genera of plant parasitic nematodes were identified. Among these genera and species, three species including Boleodorus pakistanensis, Ditylenchus hexaglyphus, D. valveus are reported as new records for Iran.]]>
p. 460−467
2783-5383
Vol.30/No.3
p. 468−480
2783-5383
Vol.30/No.3
p. 481−487
2783-5383
Vol.30/No.3
p. 488−493
2783-5383
Vol.30/No.3
p. 494−504
2783-5383
Vol.30/No.3
p. 505−517
2783-5383
Vol.30/No.3
2 mm) were counted daily two or three times for 20 days. All distributions, having been formulated into the hydrotime model, were fitted to data using the PROC NLMIXED procedure of SAS, with the default optimization technique of dual quasi-Newton algorithm.
Results and Discussion: The results showed that the estimated parameters of the hydrotime model developed on the basis of Beta distribution had more certainty than the other distributions (AICc=-556.60 for M. officinalis, AICc=-847.70 for S. arvensis and AICc=-1034.20 for H. vulgare). Based on the Beta hydrotime model, values of the hydrotime constant (θH) and water potential threshold for beginning of M. officinalis seed germination (δ) were estimated to be 14.01 MPa h and -0.85 MPa, respectively. For S. arvensis, θH and δ estimated to be 22.23 MPa h and -0.98 MPa, respectively. Estimated θH and δ for H. vulgare was 48.69 MPa h and -2.47 MPa, respectively. Results of this research are in contrast to assumption of a normal distribution of base water potential of a seed population. Hence, before using a hydrothermal time model to make predictions, the distribution of base water potential within a seed sample should be examined and an appropriate equation should be selected.. The results indicated that among all three species, the Beta distribution resulting in more accurate predictions than the other distributions. The hydrotime model based on Beta distribution predicts an actual value for the phase of delay germination. In fact, less skewed in predicted germination using beta model can be related to more accurately of this function to predict the onset of germination. Shape parameter gives high flexibility to this model and allows more accurate prediction of delayed germination phase. In addition, the hydrotime model based on Beta distribution was able to prediction germination of species for which the base water potential distribution is symmetrical or unsymmetrical.
Conclusion: In this paper, a model based on the beta distribution is proposed which is not only more biologically relevant, but also provides better predictions of germination compared to the conventional model.]]>
p. 518−532
2783-5383
Vol.30/No.3
p. 533−536
2783-5383
Vol.30/No.3
p. 537−540
2783-5383
Vol.30/No.3
p. 541−546
2783-5383
Vol.30/No.3