Plantago lanceolata is it gynodioecious species: In natural populations male steriles (MS) coexist with hermaphrodites (H). Since male steriles have a reproductive disadvantage, without any compensation for their loss in male function by an increase in female function, they are expected to disappear from the population. In this study we investigated the possibility that differences in ecologically important photosynthetic characteristics, between MS and H lines of P. lanceolata, play a role in maintaining gynodioecy. One MS line and two H lines were grown under conditions of high N and light availability, as well as under either N limitation or light limitation, to investigate whether the sex types respond differently to environmental constraints. Photosynthetic light-response and CO2-response cut-yes were made, together with leaf organic N and chlorophyll determinations. There were only few small differences between the lines and since the MS line did not differ in any of the determined photosynthetic characteristics from either H line, it is unlikely that these differences are involved in maintaining male sterility in populations of P, lanceolata. The low-light-grown plants showed a high degree of acclimation its shown by a two-fold higher leaf area to leaf weight ratio (SLA), a two-fold higher investment of N in light harvesting, and higher net photosynthetic rates under low-light conditions, as compared to the high-light-grown plants. The low-N-grown plants used their organic N more efficiently in photosynthesis compared to plants grown at an optimal N supply. This was mainly due to the N-limited plants having leaves with a lower organic N content and thus lower photosynthetic capacities. To a lesser extent it was due to the higher value for the curvature factor of the light-response curves of the N- limited plants, to their decreased rates of photorespiration and possibly to their relatively higher allocation of organic N to photosynthetic functions. [KEYWORDS: chlorophyll; CO2-response curve; electron transport; gynodioecy; light-response curve; male sterility N limitation; photosynthesis; photosynthetic nitrogen use efficiency; Plantago lanceolata; Rubisco; shade acclimation Gas-exchange; response curve; respiration; acclimation; assimilation; nutrition; gradients; nitrate; carbon; model]
Original languageEnglish
JournalPhysiologia Plantarum
Journal publication date1996

ID: 116365