Absorption of Foliar-Applied 32P by Successive Leaves, and Distribution Patterns in Relation to Early Fruiting and Abscission in the Cowpea (Vigna unguiculata L.)

Publisher Website
Google Scholar
Abstract
In controlled environment experiments, the uptake and distribution patterns of 32 P were studied in relation to flowering and fruiting in the cowpea. Absorption by the plant, retention by the fed leaf, and translocation to various plant parts depended on the position and age of the fed leaf. At the 4-leaf stage, when the terminal leaflet of the first trifoliate (oldest) was fed 32 P, the plant absorbed 43 per cent of total radioactivity supplied in 24 h. The percentages resulting from the feeding of trifoliates 2, 3, and 4 (youngest) were 58, 71, and 73 respectively. Trifoliate 1 retained 34 per cent of the total radioactivity, while trifoliate 4 retained 68 per cent. Of the plant tissues, the root accumulated the greatest amounts of the P exported by the fed leaflet, with the feeding of trifoliates 1, 2, or 3. With the feeding of trifoliate 4, however, the root imported only 0.2 per cent of total radioactivity. When the plants had one set of flowers fully open at raceme 1, the flowers imported 0.19 per cent of total radioactivity in the cultivar Adzuki, and 0.36 per cent in the cultivar Early Ramshorn. When the raceme 1 flowers developed into fruits while the raceme 2 flowers were fully open, the raceme 1 fruit import of radioactivity was 2.61 per cent in Adzuki and 14.21 per cent in Early Ramshorn. Raceme 1 fruits of Early Ramshorn thus accumulated five times as much P radioactivity as those of Adzuki. When racemes 1 and 2 both bore fruits, removal of the raceme 1 fruits just prior to 32 P feeding, led to the import by the raceme 2 fruits of 0.25 per cent in Adzuki and 0.09 per cent in Early Ramshorn. The raceme 1 fruits constituted a more potent sink for 32 P in Early Ramshorn than in Adzuki. The results are discussed in relation to the known patterns of premature abscission of flowers and young fruits in the two cultivars.

This publication has 0 references indexed in Scilit: