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Abstract
High proportions of 3x hybrids were obtained from crosses of 4x highly sexual seed parents by 2x pollen parents in Citrus. This is in contrast to the low proportions usually obtained with 4x partly apomictic cultivars as seed parents, or with 4x plants used as pollen parents. Initial survival of small germinating seeds and very young seedlings was low but later growth vigor has been high. Ten 4x and 9 aneuploid (near 3x) plants were identified.
Abstract
Investigations on a widely distributed variant Navel orange led to the need for reproducible, quantitative measurements of flesh firmness of orange fruits. Previous work using pressure devices on the surface of transversely-cut citrus fruits had resulted in erratic results. Whole fruit compression tests failed to show significant differences between samples of the variant and normal fruits (Table 1). In preliminary trials, dropping a pointed rod a given distance through a guide tube onto the transversely-cut fruit gave reproducible results. On the basis of the preliminary results, the present instrument, Fig. 1, was constructed and used in subsequent tests comparing variant Navel oranges with normal Navel oranges. In all plantings tested, the variant trees could be identified by means of the differences in the penetrometer measurement. The absolute values varied from planting to planting and on different sampling dates, but the differences between the two fruit types were always detectable. Results from the first plantings sampled are given in Table 1.