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  • Author or Editor: L. J. LaCroix x
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L. J. LaCroix and L. M. Lenz

Abstract

Iron deficiency chlorosis is a serious problem when many of a number of woody and herbaceous ornamental and fruit plants are grown on calcareous soils. Soil amendments, such as the various iron chelates, have been used with varying success (1,2,3,4), however, except for foliar application on citrus, chelates have found limited use because of their high cost and erratic or less than satisfactory results. The simple inheritance of chlorosis resistance in soybeans is well known (5), however, the few attempts to select chlorosis resistant fruit trees have been rather unsuccessful (6,7). Trees frequently will show no signs of chlorosis until the rcot system penetrates highly calcareous subsoil layers. Thus attempts to select for chlorosis resistance have given erratic year to year results and have, in general, been unsuccessful even after several years of testing.

Open access

E. J. Hogue and L. J. LaCroix

Abstract

For prompt germination the seed of Russian olive (Elaeagnus angustifolia L.) required 9 to 12 weeks of after-ripening at a temperature of 5° C. When fruit and endocarp were removed, 50–60% of the non-after-ripened seed germinated. Complete germination was obtained by removing the endocarp and the seed coats. The germination inhibition appeared to be related to non-leachable inhibitors in both of these structures, and their influence was almost entirely restricted to the radicle end of the embryo. Kinetin was very effective in breaking the dormancy linked to the seed coats but did not influence dormancy when the endocarp was present.

Open access

D. E. Vanstone and L. J. LaCroix

Abstract

The seed of black ash, Fraxinus nigra Marsh., borne in a single samara, normally ripens in the autumn. At that time the seed contains an embryo which is both immature and dormant. In order to overcome this dual delay to germination, the seed can be matured in moist peat moss for 18 weeks at 21° followed by after-ripening for 18 weeks at 4°.

Treatment at warm temperature matured the embryo, whereas the subsequent cool temperature after-ripened the dormant embryo. During maturation the embryo length doubled, the dry weight tripled and the cotyledons showed visual evidence of differentiation. On the other hand, for dormancy to be overcome a metabolic shift in the embryo occurred during the cool period to provide the active metabolism needed by a germinating seed. This was reflected by a 5 percent per week increase in the respiration capacity of the embryo and a reduction in the amount of oil in the seed.

Open access

L. J. LaCroix, S. J. Westaway, and A. C. Ferguson

Abstract

Infra-red light induced stem elongation of several species of plants. Tomato plants also had reduced fruit yield. Geraniums had wider leaves and longer internodes and flower stalks, but the no. of flower stalks was unaffected by infra-red treatment. These effects should be taken into consideration if infra-red heating is to be used in greenhouse operations.