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Abstract
We have witnessed an increasing interest in national and international food production over the past several years. The need for increased food production is covered in several documents such as Agricultural Production Efficiency (1), World Food and Nutrition Study (3). The World Food Problem (2), Food for Billions (5). Photosynthesis, Photorespiration and Plant Production (25), CO2 Metabolism and Plant Production (7) and an entire issue of Science (18).
Abstract
Tomato plants were grown in sand culture at 8 levels of K ranging from 0 to 10 meq per liter of nutrient solution. Fully ripened fruit were picked and rated internally and externally for abnormal pigmentation. Total carotenoids were analyzed and the extract fractionated into 3 groups: hydrocarbon, monohydroxy and polyhydroxy. The hydrocarbon fraction was further separated chromatographically into 6 individual pigments. Most of the carotenoids, lycopene in particular, generally increased with increasing K concn. A notable exception to this pattern was β-carotene which decreased with increasing K concn. Possible modes of action of K are discussed.
Abstract
The effects of growth retardants succinic acid 2,2-dimethylhydrazide (SADH), (2-chloroethyl) trimethylammonium chloride (CCC) and 2,4-dichlorobenzy 1-tributylphosphonim chloride (CBBP) on growth and flowering of Brassica oleracea var. italica, cv. ‘Waltham 29’ (broccoli) were investigated. All 3 compounds reduced plant height. At higher concn SADH reduced the no. of plants flowering in both cold and non-cold treated plants. Neither floral induction nor leaf no. was significantly affected by CBBP or CCC. Leaf no. increased with increasing conc of SADH, as a probable result of the increased inhibition of floral initiation.
Abstract
Floral induction of broccoli (Brassica oleracea italica) ‘Waltham 29’ at low temp (5°C) was associated with increasing levels of starch and sugar in the shoot tip. This same relationship was found in experiments concerning plant age, duration of cold treatment, leaf removal before and during cold treatment, and treatment with succinic acid 2,2-dimethylhydrazide (SADH) or gibberellic acid (GA3).
Greenhouse experiments with plants grown continuously at 16-21°C or 21-27°C indicated that high carbohydrate levels are not necessarily associated with flowering. Flowering was delayed at the higher temp with little difference in carbohydrate level.
Abstract
Research related to plant growth and development over the past 75 years has brought us to a point where the vegetable plants we grow today have been developed to fit the needs of the home gardener, the greenhouse grower, the large scale fresh market grower and the vegetable processing industry. Through this research, changes have come about that contribute to a better understanding of the basic genetic and physiological mechanisms that control plant habit, sex expression, flowering, and fruit type. These four broad areas will be covered to demonstrate the diversity and scope of knowledge concerning growth and development that has accumulated in the 20th century. This knowledge opens doors for further work on the major crops and for beginning work on crops that hold promise for the future. The flexibility and complexity of plants and plant processes allow us to look at plants the way we find them, envision them the way they can be changed to best serve us and plan our procedures for developing them for the future.
Abstract
The distribution of l4C-assimilates was examined in pot-grown ‘Redkote’ and ‘Michelite-62’ bean plants in which a lower or upper leaf was dosed with 14CO2 at flowering, pod expansion, or pod maturation. Assimilates from the leaf at node 4 moved primarily to the roots at flowering, but were translocated to actively growing pods at later stages. Dosing of the terminal trifoliate of ‘Redkote’ resulted in radiocarbon transfer exclusively to the subtending pods during pod expansion and maturation. Distribution from leaves on branches of both varieties was restricted to pods on the branch. When the main-stem node-7 leaf of ‘Michelite-62’ was dosed, 51% of the activity was recovered from node-7 axillary pods, and less from pods at nearby nodes. Thus middle and lower main-stem leaves of beans generally supply assimilates to several centers of active growth, while distribution from upper mainstem and branch leaves is more restricted.