Heather Howard

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The Andigena potatoes (Solanum tuberosum ssp.andigena) of the Commonwealth Potato Collection (C.P.C.) were screened for resistance to ‘non-pathotype A’ populations ofHeterodera rostochiensis. Three populations were used: Duddingston (pathotype B), Nocton (pathotype C) and Changed Little Ouse (pathotype C). Resistance was found in C.P.C. 2775, 2802 and 2805.(More)
Considerable differences occurred between selectors in intensity of selection when selecting the same potato clones in S, C1 and C2 (seedling, first clonal and second clonal years). Comparing clones selected or discarded in one year with clones selected or discarded in previous years indicated the effectiveness of selection and large differences were shown(More)
1. It is suggested that there may exist small structural differences between the chromosomes of the genoms of the tuber-bearingSolanum species. 2. For the diploid (2n = 24) species, the best evidence for such small structural differences is obtained from a comparative study of meiosis in amphidiploids and autotetraploids. 3. The problem is more complex in(More)
Haploid plants of Solanum demissum Lindl. have been reported by BAINS and HOWARD (1950) and DODDS (1950) to occur frequently in crosses of S. demissum female • diploid species such as S. rybinii, S. stenotomum and S. torlapanum. At first metaphase of meiosis in these haploid plants BAINS and HOWARD (1950) found a mean frequency of 4.74 bivalents per. cell(More)
In breeding potatoes resistant to Might (Phytophthora i,J~feslans de Bary), the wild, Mexican hexaploid (2n=72) species ~S'olanu~n demissu~n Lindl. has usually been used as the source of resistance, e.g. Black (19,13, 1945a, b), O'Connor (1933), O'Connor & Salaman (1931), Reddick (1940, 1943), and Salaman (1931, i934, 1937, 1938, 1941). Used as the female(More)
] . ][N~ZODUOTZON In two previous papers (Howard, 1939, 1942) it w~s found in the genus B'ra~i~ct, first, tMt in certain cases large numbers of good seeds could be obfiained from crosses of the fFTe fietraptoid female • diploid bu~ not f~om fihose of the type diploid female x r and secondly, that triploid seeds from such crosses were only about 20 % of the(More)
1. Iutroducbion 2, C y t o l o g y of ~he $'~ g e n e r a t i o n 3. Theo re t i c a l cons ide ra t ions of anaph id ip l e id f e r t i l i t y 4. OytoIogy of t he 27' a a n d 7,',~ g e n e r a t i o n s 5. Fm ' t f i i t y of 2~al)/m.no-Brassi~a amp.h id ip lo ids 6. I n h e r i t a n c e of in£ertiIit.y in ~aphano-2r~,ssica amph id ip lo id s 7. Disc~ss(More)
In the variety Arran Victory, which has purple tubers, there was found a tuber half purple and half pink. The pink half produced a plant which had pink tubers with small purple patches. X-ray irradiation of these tubers gave plants which had about five per cent of pink tubers without the purple patches. Breeding and eye-excision experments showed that the(More)