Do larger plants produce more and better seeds and seedlings? Testing the hypothesis in a globose cactus, Wigginsia sessiliflora

CEBALLOS, C.; LAS PEÑAS, M.L.; ALISCIONI, N.L.; FERRERO, M.C.; GURVICH, D.E.

BOTANY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

Año: 2022

1916-2790

In iteroparous plants, an increase in allocation to reproduction is expected with increasing plant size. The aim of this studywas to analyze how plant diameter is related to total produced seed mass, seed number, mean seed mass, percentage andmean germination time (MGT), and seedling size and shape in Wigginsia sessiliflora (Hook.) D.M. Porter (Cactaceae), a slowgrowingglobose species from central Argentina. Plant diameter was measured in a population of 185 individuals, and fruitswere collected. We counted all seeds to obtain seed number, and weighed them to get seed mass and total seed mass. Seedswere germinated and data of germination percentage and MGT were collected. We also measured the size (height and width)and shape of seedlings (height/width relationship). Fifty-four percent of the plants did not produce fruits. Plant diameter wasunimodally related to fruit number, total seed mass, and seed number, i.e., intermediate-sized plants presented the highestvalues. Height and shape of seedlings were positively related to plant diameter. Surprisingly, plant diameter was related in aunimodal way to reproductive outputs. As plants grow, surface–volume ratio decreases, meaning that respiratory losses wouldbe higher than the increase in photosynthetic capacity; therefore, fewer resources may be available for reproduction.