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Sources of Corn, Zea Mays L., Resistance to Thrips, Frankliniella Occidentalis (Pergande) and Frankliniella Williamsi Hood, in Mexico

出版	Kansas State University, 1970
URL	http://books.google.com.hk/books?id=_R9euAAACAAJ&hl=&source=gbs_api

註釋Frank'iniella spp. have been reported to attack corn wherever it is grown in Mexico. The most widespread species is F. williamsi Hood. Studies were conducted at the Roque Guanajuato Agricultural Experiment Station and at the Tepalcingo, Morelos Agricultural Experimental Station with the goal of developing corn with resistance to thrips damage. Entries totaling 266 were tested in the field at Roque Guanajuato in the spring of 1967. Differences in preference and tolerance were detected. Greatest resistance occurred in crosses between Celaya, Ancho. Chileno and Tehuacan types, which were further tested at Tepalcingo, Morelos. The 60 most resistant entries were allowed to interpollinate in isolation.The most susceptible were detasseled.The resulting population was named the Thrips Resistant Synthetic. In 1968, the Thrips Resistant Synthetic was compared with five other corn populations at Roque Guanajuato. The Thrips Resistant Synthetic was the most resistant. A laboratory technique for artificial infestation of corn seedlings with a known number of thrips was developed. It allowed studies on infestation levels, varietal thrips preference, varietal tolerance to thrips damage, inheritance of corn resistance to damage and effect of soil moisture and plant age on thrips damage. It was found that (1) an infestation level between 20 and 25 thrips per plant gave the maximum spread of varietal differences; (2) the Thrips Resistant Synthetic and Oaxaca Group 4O were the most resistant varieties; (3) the most preferred was Jalisco Group 39 (an attractant is indicated); (4) resistance is a recessive trait; (5) in moist soil the corn plants withstand infestation better than in dry soil; and (6) older plants withstand injury better than younger plants. Performance of the Thrips Resistant Synthetic in the 1968 field tests and in laboratory tests indicated a good source from which highly resistant corn material can be developed. Screening in the laboratory S1 Iines derived from the Thrips Resisant Synthetic indicated that this approach can be used for increasing the resistance of that synthetic. The life cycle of F. williamsi was investigated in the laboratory. It took an average of 16.4 days to complete its development. Weekly collections on wild and cultivated plants indicated that some breeding takes place during winter in the Bajio area. Seventeen plant hosts were recognized. The first corn planted in spring was lightly infested with adult thrips (3 to 5 per plant) coming from the winter hosts. The population increased on corn and reached a peak just prior to the rainy season. Then it declined sharply.