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Stem Cuttings (stem + cutting)
Selected AbstractsThe Influence Of Salinity On Verticillium dahliae In Stem Cuttings Of Five Olive CultivarsJOURNAL OF PHYTOPATHOLOGY, Issue 10 2007A. G. Levin Abstract Verticillium dahliae represents one of the main limiting factors in olive production in the Mediterranean countries. Increasing shortage of fresh water and land, increase the pressure on using alternative sources of marginal or saline water, and land previously cropped with V. dahliae host plants. The objective of the present study was to evaluate the influence of salinity on V. dahliae expression in olive stem cuttings. V. dahliae- inoculated cuttings of cvs. Picual, Frantoio, Mansanillo and Barnea, showed higher senescence symptoms than their non-inoculated controls. Colonization levels obtained in cv. Picual were significantly higher than in cv. Frantoio. Manzanillo was the most sensitive cultivar to salinity alone, with significant senescence symptoms in 4 and 6 dS/m NaCl treatments. When cv. Manzanillo was exposed to both salinity and V. dahliae, significantly higher senescence symptoms were obtained as compared with each of them separately. Senescence symptoms of cv. Picual exposed to V. dahliae, whether or not in combination with saline solutions, were significantly higher than those when cuttings were exposed to a saline solution alone. In cv. Frantoio, which is more resistant to salinity than the other cultivars, significantly high senescence symptoms were observed only in combination of V. dahliae and high saline concentration (8 dS/m). The fungal colonization index in cv. Manzanillo in high salinity (8 dS/m) was significantly higher than in the treatment without salt. In cv. Barnea, colonization index in 8 dS/m salinity was significantly higher than in the 4 dS/m concentration or control (fresh water). In conclusion, our findings demonstrate the interaction between V. dahliae and saline irrigation in various cultivars. Thus, stem cuttings could serve as an effective screening method in breeding olive clones for V. dahliae resistance, salt tolerance and their interaction. [source] Bark borer Semanotus japonicus (Col., Cerambycidae) utilization of Japanese cedar Cryptomeria japonica: a delicate balance between a primary and secondary insectJOURNAL OF APPLIED ENTOMOLOGY, Issue 7-8 2000E. Shibata To understand how S. japonicus is affected by host nutrition and resin flow, newly hatched larvae were introduced into stressed cedar trees. Stress was induced by either heavy pruning, stem cutting (i.e. removing the side branches and top of tree), or girdling. Larval mortality due to resin flow in the ,heavy pruning treatment' and the ,stem cutting treatment' tended to be lower than that in the untreated control cedar trees where all larvae were drowned by resin flow. Parasitism to the larval stage was observed in the stem-cutting trees, not in living trees, suggesting that S. japonicus may avoid parasitism in living cedar trees because few volatiles are produced. In the ,stem-girdling treatment', although more than 90% of the introduced larvae died due to poor nutrition below the girdle, 7.8% of the larvae above the girdle reached the adult stage. The live body weight of the adults collected from above the girdle was similar to those taken from naturally infested cedar trees. These results suggest that S. japonicus requires adequate host nutrition but that larvae are defenceless against high resin flow. Thus, S. japonicus seems to be in a transition state between being primary or secondary with respect to its attack behavior on living cedar trees. [source] The effect of periderm formation in the cortex of Pinus thunbergii on early invasion by the pinewood nematodeFOREST PATHOLOGY, Issue 3 2000Y. Ichihara Summary The distribution of cortical resin canals and periderm formation in the cortex of Pinus thunbergii was studied in relation to early invasion of the pinewood nematode, Bursaphelenchus xylophilus. Nematode invasion was restricted in stem cuttings of P. thunbergii in which periderm closed cortical resin canals. Early invasion of the nematodes was also restricted in stem cuttings where wound periderm had formed in response to prior nematode inoculation. It was concluded that early invasion of pinewood nematodes in living bark tissue is restricted by periderm in mature stems and by wound periderm that had formed as the result of previous nematode infection. [source] The Influence Of Salinity On Verticillium dahliae In Stem Cuttings Of Five Olive CultivarsJOURNAL OF PHYTOPATHOLOGY, Issue 10 2007A. G. Levin Abstract Verticillium dahliae represents one of the main limiting factors in olive production in the Mediterranean countries. Increasing shortage of fresh water and land, increase the pressure on using alternative sources of marginal or saline water, and land previously cropped with V. dahliae host plants. The objective of the present study was to evaluate the influence of salinity on V. dahliae expression in olive stem cuttings. V. dahliae- inoculated cuttings of cvs. Picual, Frantoio, Mansanillo and Barnea, showed higher senescence symptoms than their non-inoculated controls. Colonization levels obtained in cv. Picual were significantly higher than in cv. Frantoio. Manzanillo was the most sensitive cultivar to salinity alone, with significant senescence symptoms in 4 and 6 dS/m NaCl treatments. When cv. Manzanillo was exposed to both salinity and V. dahliae, significantly higher senescence symptoms were obtained as compared with each of them separately. Senescence symptoms of cv. Picual exposed to V. dahliae, whether or not in combination with saline solutions, were significantly higher than those when cuttings were exposed to a saline solution alone. In cv. Frantoio, which is more resistant to salinity than the other cultivars, significantly high senescence symptoms were observed only in combination of V. dahliae and high saline concentration (8 dS/m). The fungal colonization index in cv. Manzanillo in high salinity (8 dS/m) was significantly higher than in the treatment without salt. In cv. Barnea, colonization index in 8 dS/m salinity was significantly higher than in the 4 dS/m concentration or control (fresh water). In conclusion, our findings demonstrate the interaction between V. dahliae and saline irrigation in various cultivars. Thus, stem cuttings could serve as an effective screening method in breeding olive clones for V. dahliae resistance, salt tolerance and their interaction. [source] Insights on the evolution of a vegetatively propagated crop speciesMOLECULAR ECOLOGY, Issue 14 2007KENNETH M. OLSEN The opportunity for gene flow between a vegetatively propagated crop and its wild relatives is expected to be much lower than for seed-propagated crops, since sexual reproduction in the crop occurs only infrequently. A study by Duputié and colleagues now demonstrates evidence of sexual reproduction between a vegetatively propagated crop and a closely related wild congener. Working in French Guiana, these workers have documented a hybrid zone arising from introgression between cassava (Manihot esculenta ssp. esculenta, Euphorbiaceae), which is propagated by stem cuttings, and wild Manihot populations growing in close proximity. Patterns of heterozygosity suggest that there are little,to,no barriers to reproduction between the crop and these wild populations. Previous work by these researchers has documented the importance of occasional sexual reproduction for the development of cassava varieties in traditional Amerindian farming systems. Taken together with their previous work, these new findings suggest that gene flow between wild Manihot populations and cassava plants could potentially play a much greater role in the crop's evolution than previously thought. [source] | ||||||||||