Regulation of assimilate partitioning in flowering plants of the monopodial orchid Aranda Noorah Alsagoff

Abstract

SII M M A R YRadiocarbon dosing of leaves and source-sink manipulation treatments were used to clarify how assimilate partitioning is regulated in flowering plants of a monopodial Aranda orchid. The inflorescence was the dominant sink for all test leaves that were selected to determine patterns of "C-assimilate partitioning. Defoliation treatments had only minor effects on the distribution of '^C-assimilate between the inflorescence and vegetative apical shoot. Excision of the inflorescence resulted in greater proportions of '''C-assimilate being sent to all other sinks. Loss of the vegetative apical shoot had a quite different effect in that greater proportions of ^*C-assimilate were exported only to the inflorescence. Rates of '''C assimilation of remaining leaves were often raised in defoliated plants although this effect was not consistent for a single, residual leaf unless the vegetative apical shoot was also excised. Our results highlight the complexity of source-sink relationships in indeterminate plant types showing simultaneous vegetative and reproductive growth. We suggest that inflorescence growth in monopodial orchids such as Aranda is primarily source-limited although significant sink limitations for assimilate gain by the inflorescence exist because of a modulating effect of the vegetative apical shoot on inflorescence sink strength and the ability of source leaves to respond positively to increased sink demand.

Dynamics of Mineral Uptake and Plant Function during Development of Drug-Type Medical Cannabis Plants

“…Toward the end of the reproductive development, it is inevitable that source-sink relationships and resource partitioning in the plant will change, and the translocation of nutrients and carbohydrates from vegetative to reproductive organs will increase, to support inflorescence and seed development. This mechanism, which has already been demonstrated in other plant species [67][68][69], correlates with the substantial increase in inflorescence production (Figure 3D) and the cessation of leaf production (Figure 3A) in the second half of the reproductive phase. Taken together, these data suggest that the leaves' physiological function decreases by the end of the reproductive growth phase on account of divergence of resources to the reproductive inflorescences, as can be seen for the RM cultivar (Figures 3 and 4).…”

The physiological ecology of vascular epiphytes: current knowledge, open questions

“…carbon gainuloss) of one particular organ (mostly leaves), and at one particular time scale (mostly short term). The integration of various processes within the organism (Clifford et al, 1995;Yong and Hew, 1995), and particularly long-term trade-offs between vegetative and reproductive function, have received much less attention. As pointed out repeatedly throughout this review, there is still a long way to go towards linking the physiology of single organs to the comportment of entire individuals, let alone to the structure and dynamics of populations and communities.…”

Resource re‐allocation following fruit removal in cucurbits: patterns in cantaloupe melons

“…Overall, the pattern of resource allocation is believed to be integrated throughout a plant (Wardlaw, 1968;Clifford, Neo & Hew, 1995). The various theories proposed to account for patterns of resource allocation in plants all assume that vegetative and reproductive processes compete for a common pool of resources and that an increase in one activity necessarily results in a proportional decrease in the others (Reekie & Bazzaz, 1987;Stearns, 1989;Ashman, 1994).…”