Test on Wilt-Resistance of Simple Hybrides F7 and Beckross Hybrid Lines F6 B1 of G. hirsutum L. of Cotton to New Virulent Isolates of Fungus Fusarium verticillioides and Verticillium dahlia e

The article presents the results of studies on the resistance of hybrid cotton lines to a new virulent isolate (strain) of the fungus Fusarium verticillioides upon inoculation of the host plant. Based on the studies, it was found that the complex genotypic resistance of the studied lines, when the host plants are inoculated with isolates of −100 V. dahliae Kleb fungus and 103 Fusarium verticillioides fungi, depends on the degree of resistance of the parental forms and their combination ability.


Introduction
The genetic basis of wilttolerance of various varieties, forms, and types of cotton-plant was studied by Arutyunova L. G., Gesos K. F., Polotebnova T. U. [1], D. V. Ter-Avanesyan [2] [3], S. M. Mirakhmedov et al. [4], A. Abdullaev [5], R. G. Kim, A. Marupov et al. [6] [7]. It should be noted that in nature there is a constant conjugate evolution of the host plant and the parasite of the fungi Verticillium and Fusarium, which contribute to the emergence of new, more virulent pathogens (strains) of the fungus that can infect previously resistant varieties of cotton and thereby the search for new methods and donors of resistance to this complicate disease, and the creation of resistant and highly productive varieties with a complex useful features are becoming more relevant. So according to the data presented by the doctor of agricultural sciences A. Marupov (from 2002 to present), in recent years there has been an increase in the incidence of inflatedness of medium-fiber varieties of cotton to new pathogens of the genus Fusarium wilt of the species Fusarium verticillioides, especially in varieties of Bukhara type, due to the violation and non-compliance, special anti-rotation schemes of crop rotation. Therefore, this species began to adapt to medium-fiber varieties of cotton.
It should be noted that the soil is one of the most suitable natural habitats for most Fusarium species. Fusarium fungi exist in active formin soil, colonize various plant debris, and grow in the rhizosphere and on the root surface, using Therefore, the study of the resistance of variety specimens, wild and ruderal forms, varieties, lines, and hybrids of cotton of the species G. hirsutum L. to the fungus of the species Fusarium verticillioides is a very urgent problem of the present and future in cotton breeding with the aim of creating cotton varieties with a complex of resistance to verticillus and Fusarium wilt.

Research Objects and Methods
In the regard, methods are used in experimental biology and genetics of traditional plants [1] [2]. Monospore isolates of the fungus Fusarium verticillioides and the fungus Verticillium Klebwere isolated in UzNIIZR in the laboratory of the wilt under the direction of A. Marupov, Doctor of Agricultural Sciences.
Artificial infection of plants was carried out in early July in the phase of the beginning of budding on backcross hybrid plants F6B1 and F6, F7.
Inoculation at the root neck, hung a label on which the date of inoculation, the onset and degree of manifestation of the disease were noted on the inoculation plants.

Result and Discussion
The results of studies on the resistance of hybrid cotton lines to a new virulent  Table 1.
It can be seen as in Table 1 This suggests that these lines do not possess genotypic immunity to virulent isolate-103.   Table 2 shows

Conclusions
Thus, the complex genotypic resistance of the studied lines to the inoculation of the host plants with isolates of −100 of the fungus V. dahliae Kleb and 103 of the fungus Fusarium verticillioides depends on the degree of resistance of the parental forms and their combination ability, as well as on the orientation of the selection, on the physiological state of the plants, the size of the degree of infectiousness , specific physiological activity of the pathogen, its aggressiveness and toxicity.
The lines L-222 and L-431 have a high integrated resistance to both studied Fusarium verticillioides and V. dahliae Kleb isolates. The lines L-396, L-362 and L-2771 turned out to be relatively stable.