Studies in Fruit Growth and in Vernalization

Author: Jansen, Leonard Leroy

Year: 1953

Degree: Dissertation (Ph.D.)

Advisor: Bonner, James Frederick

Committee Member: Unknown, Unknown

Option: Biology; Biochemistry

DOI: 10.7907/9JPG-AE41

Abstract

Growth and development of flowers and fruits of red currant tomato (Lycopersicon pimpinellifolium) have been studied both on the intact plant and with the excised flower cultivated in vitro. A new interpretation of development of the inflorescence has been presented. Two types of growth response of ovaries of pollinated flowers have been identified both on the plant and in culture. In one type growth is linear and in the other it is exponential. The latter type, on the plant, produces seeded fruits, and size of fruits is correlated with number of seeds. Development on the plant is apparently optimal at a night temperature of 17[degrees]C. Smog is detrimental to development.

Growth of the pollinated ovary in vitro can be supported on a minimal medium of mineral salts and sucrose. The two response types differ in carbohydrate requirements. A pollination-fertilization factor is postulated as the primary difference between them. Growth of the ovary in vitro can be influenced by temperature, auxin, casein hydrolysate, and concentration of sucrose. The temperature optimum for development in culture differs from that for development on the plant. Mechanisms of the responses have been discussed.

The cold-requiring processes which promote flower initiation in Petkus winter rye have been analyzed more critically for their oxygen and sugar requirements by vernalizing the excised embryos under atmospheres of air or nitrogen on media with or without sugar. The first partial process of vernalization requires sugar but does not require oxygen. The second process does not require sugar but is dependent upon oxygen. Separation of the partial processes now becomes possible.

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