Sweetpotato Resistance Research Articles

Resistance to Root-knot Nematodes (Meloidogynespp.) in Vegetable Crops

Abstract The development of root-knot nematode resistant vegetable varieties has provided an alternative control method to chemical and crop rotation. The term resistance is discussed. Work on 18 vegetables is reviewed. Thirty tomato strains resistant to one or more Meloidogyne sp. are listed, there was a marked absence of reports on varieties resistant to M. hapla. Several workers have observed resistance in some cultivated and wild Solanum spp. The resistance could be increased by further sib and backcrossing experiments. Eggplant varieties tested for resistance to Meloidogyne spp. showed varying degrees of resistance in about 14 varieties. Further backcrossing studies between Solanum melongena and S. sysimbrifolium could provide useful results. Tests on resistance to nematodes in pepper have revealed many resistant varieties. All the pepper varieties tested were susceptible to M. hapla. The nature of resistance in sweet potato has been studied. Some varieties of Cucumis spp. have been found to be resis...

Resistance in sweetpotato to the scurf and black rot pathogens

Abstract Over 600 sweetpotatoes (Ipomoea halalas (L.) Lam.) were evaluated for resistance to black rot (Ceratocystis fimbriata Ell. & Halst.) and 506 to scurf (Monilochaetes infuscans Eli. & Halst.). Vine cuttings from the varieties were inoculated to initially evaluate disease resistance to both fungi. From the3e tests approximately 8% of the varieties were selected for re:;istance to black rot and 7% for resistance to scurf. Enlarged roots of these varieties were inoculated with the respective pathogens, and lesion diameter after incubation was the criterion for measuring resistance. No variety was immune from eithcr pathogen. For both diseases, varieties selected from the vine cutting inoculations developed symptoms in their inoculated roots ranging from rcsistant to very susceptible; and there was no correlation between the disease reaction expressed by vine cuttings and that by roots of the varieties. Most varieties with superior resistance in their enlarged roots to either scurf or black rot came fr...

Varietal resistance of sweet Potato to “shukuyo” mosaic disease

Varietal resistance of sweet Potato to “shukuyo” mosaic disease

黒斑病甘藷の病理化学的研究

(1) Two components, A2 with carboxyl and A1 without, were isolated from the.polyphenolic component A in the previous paper by counter current distribution method. According to their property, these were assumed to be the delivatives of caffeic acid. However it was not clarified whether the new comp A1 might be produced abundantly because of the abnormal metabolism caused by the penetration of the fungus, or converted from the other polyphels during the extraction. (2) To examine the antifungal activity of these components, Ceratostomella fimbriata was cultivated in the medium containing 0.5, 0.1 and 0.01% A1 and A2 as well as chloroginic acid respectively, but it was not inhibited noticeably, i.e., by 0.5% slightly inhibited and 0.01% facilitated a little. The antibiotic property of A1 was stronger than the other two in a slight degree. The quinons were produced from these polyphenols by the action of the oxidase secreted from the fungus during the cultivation, but their antibiotic activity was scarecely observed. (3) As the determination method, K3FeCN6, oxidation-method was improved and used in comparison with the oxidase method described in the last paper; consequently, nearly the same quantitative values were obtained. (4) Selecting Var. Norin No. 1, Norin No. 5 and Okinawa No. 100, the relation between the amount of polyphenols, accumulated by the penetration of the mycellium and the depth of penetration was examined. The result was as follows; the amount was found to be larger in Norin No. 1 end No. 5 than Okinawa No. 100. While the depth of penetration was found to be in the following order;. Norin No. 5> Norin No. I>Okinawa No. 100. Consequently it waa considered that polyphenols and their derived quinon compunds were not greatly capable of inhibiting the tungus growth in tissue of the sweet potato. (5) However, the oxidized polymers (perhaps melanine-like substances) of polyphenols might inhibit the penetretion mechanically by their filling the cells. (6) Therefore, the reason of the resistance of sweet potato against the fungus must be inquired in the other physical and chemical factors.