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- Author or Editor: P. H. Williams x
Abstract
Hybrid crucifers have been produced via the S-allele controlled sporophytic incompatibility, a system which is generally limited by intensive labor input and occasional instability in the expression of certain S-alleles. Additionally, most F1 hybrids lack the broad spectrum of disease resistance essential for wide adaptability. A cytoplasmic male sterile (ems) system in brassica, induced by the substitution of Brassica nuclei into a ems Raphanus cytoplasm, R1 (3), has provided a potentially useful system for the production of brassica hybrids. Moreover, the pollen control provided by the R1 ems system facilitates the incorporation of disease resistance by backcrossing ems plants to resistant recurrent parents. Based on this approach, we have developed ems Brassica campestris L. germplasms with resistance to clubroot, (caused by Plasmodiophora brassicae Wor.), downy mildew [Peronospora parasitica (Pers.) Ex. Fr.], and turnip mosaic (turnip mosaic virus) (5). In this report, we describe the release of 5 lines of ems B. campestris ssp. pekinensis (Chinese cabbage): Badger 28A, 28B, 28C, 28D, and 28E; 2 lines of ems B. campestris ssp. chinensis (pak choy): Badger 29A, and 29B; one line of ems B. campestris ssp. narinosa: Badger 30; and one line of ems B. campestris ssp. rapifera (turnip): Badger 31. These breeding lines would be potentially useful for the production of multiple-disease-resistant (MDR) B. campestris F1 hybrids.
Abstract
Spontaneous mutations, variegated virescent (vvi) and yellow plant (yp) in cucumber (Cucumis sativus L.), were controlled by single recessive genes recognizable in the cotyledonary stage and in mature plants.
Abstract
Since its introduction more than 50 years ago, monogenic dominant “Type A” resistance has successfully controlled cabbage yellows, caused by Fusarium oxysporum Schlect. f. sp. conglutinans (Wr.) Snyd. & Hans., race 1 (FOCI). Recently, a new pathotype capable of overcoming Type A resistance was found in California and designated race 5 (3). Investigations of the relationship among the races revealed that race 1 and race 5 were more closely related to each other than they were to the other races, justifying the reclassification of the F. oxysporum on crucifers (P.W.B., unpublished data). F. oxysporum f. sp. conglutinans race 5 is now designated race 2 (F0C2).
Abstract
The inheritance of 7 characters in Raphanus sativus L. was studied. Resistant reaction to Albugo Candida race 1, Ac1 , pink pigmentation in plants, Pi, and purple colored pods in R. sativus var. caudatus. Pu, are controlled by single dominant genes, Ac1 and Pi are linked and 3.28 map units apart. Male sterility, ms1 , yellow-green leaves, yg, and cream pollen, cp, are all controlled by separate, single recessive genes. Digenic recessives, gf1gf2 , control green flecking on leaves. No linkage could be detected between Ac1 and ms1 or between ms1 and yg.
Abstract
Yellow cotyledon, yc-2, and revolute cotyledon, rc, were induced in seed of cucumber (Cucumis sativus L. cv. Burpless Hybrid) by gamma radiation. Both mutations were controlled by single, recessive genes. The mutation yc-2 segregated independently of rc, yellow cotyledon, yc-1, determinate growth habit, de, non-bitter cotyledon, bi, crinkled-leaf, cr, glabrate, gib, glabrous, gl, and andromonoecious flowering habit.
Abstract
In cucumber (Cucumis sativus L.) no linkage was detected between genes for scab resistance, Ccu or bacterial wilt resistance, Bw and the 10 seedling marker genes: nonbitter cotyledon, bi; glabrous, gl; glabrate, gib; light sensitive, Is; revolute cotyledon, rc; stunted cotyledon, sc; crinkled leaf, cr; mottled cotyledon, me; and 2 yellow cotyledon genes, yc-1 and yc-2. All 12 traits were inherited monogenically. Methods were developed for the screening of scab and bacterial wilt resistance in the seedling stage.
Abstract
In cucumber (Cucumis sativus L.) a recessive gene designated sc (stunted cotyledon) produces small, dark green, concavely curved cotyledons with chlorotic tips with pleiotropic effects of plant weakness and stunting, cupped leaves, and abnormally shaped flowers.
Abstract
Heading cabbage plants, Brassica oleracea L. (Capitata group) grown under humidity conditions which allowed root pressure flow to occur during the dark period, as indicated by the occurrence of guttation from the leaf margins, remained free of tipburn. Plants grown under conditions which prevented root pressure flow from occurring developed tipburn on both wrapper and inner head leaves. The effect of root pressure flow on 45Ca transport was studied in cabbage plants in the rosette stage of growth. Heads were simulated by covering the inner leaves of the plants. 45Ca was readily transported to inner “head” leaves under high humidity which allowed root pressure flow to occur, while very little 45Ca was moved to these leaves under low humidity which prevented root pressure flow. The data indicate that root pressure flow is required to move adequate amounts of Ca to prevent tipburn in head leaves of cabbage.
Many experiments involve a complex treatment structure, and it is not always immediately obvious how such experiments should be analysed. This paper shows by way of three examples how a suitable linear model can be formulated that provides a meaningful analysis of variance table and allows mean comparisons of interest to be obtained in a straightforward manner. Possible advantages of this approach compared to the use of linear contrasts are discussed. It is concluded that a well-chosen model can often considerably simplify the analysis and lead to useful statistical inferences. The approach advocated in this paper is going to be strongest when there is good design structure present.