When the shoot apical meristem of plants is damaged or removed,fecundity and/or plant growth may suffer(under-compensation),remain unaffected(compensation)or increase(overcompensation).The latter signifies a potential...When the shoot apical meristem of plants is damaged or removed,fecundity and/or plant growth may suffer(under-compensation),remain unaffected(compensation)or increase(overcompensation).The latter signifies a potential‘cost’of apical dominance.Using natural populations of 19 herbaceous angiosperm species with a conspicuously vertical,apically dominant growth form,we removed(clipped)the shoot apical meristem for replicate plants early in the growing season to test for a potential cost of apical dominance.Clipped and unclipped(control)plants had their near neighbours removed,and were harvested after flowering production had finished but before seed dispersal.Dry mass was measured separately for aboveground body size(shoots),leaves,seeds and fruits;and number of leaves,fruits and seeds per plant were counted.We predicted that:(i)our study species(because of their strong apically dominant growth form)would respond to shoot apical meristem removal with greater branching intensity,and thus overcompensation in terms of fecundity and/or biomass;and(ii)overcompensation is particularly enabled for species that produce smaller but more leaves,and hence with a larger bud bank of axillary meristems available for deployment in branching and/or fruit production.Widely variable compensatory capacities were recorded,and with no significant between-species relationship with leaf size or leafing intensity—thus indicating no generalized potential cost of apical dominance.Overall,the results point to species-specific treatment effects on meristem allocation patterns,and suggest importance for effects involving local variation in resource availability,and between-species variation in phenology,life history traits and susceptibility to herbivory.展开更多
It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperio...It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperiod-sensitive maize cultivars. The objective of this study is to determine the photoperiod-sensitive inductive phase using reciprocal transfer between long- day （LD） （15 h d^-1） and short-day conditions （SD） （9 h d^-1）. For Huangzao 4 and CML288, days to tassel and pollen shedding were recorded, and stem apical meristems （SAM） were observed by a laser scanning confocal microscope. The results show that the seedlings are insensitive to photoperiod when they are very young （juvenile）. However, after this period, LD delays flowering and increases the leaf numbers below the inflorescence, and the length of the interval of the photoperiod-sensitive inductive phase is longer under LD conditions than under SD conditions. Transferred from SD to LD, plants show a sudden decrease in leaf numbers once sufficient SD has been received for flower commitment. While transferred from LD to SD, plants have a continuous increase in leaf numbers during the photoperiod sensitive inductive phase under LD conditions. At the same time, when plants are competent to flowers, the obvious morphology is the elongation of maize SAM. There is an obvious variance of the photoperiod sensitive phase under LD and SD conditions in different maize.展开更多
基金This work was supported by a Natural Sciences and Engineering Research Council of Canada research grant to L.W.A.
文摘When the shoot apical meristem of plants is damaged or removed,fecundity and/or plant growth may suffer(under-compensation),remain unaffected(compensation)or increase(overcompensation).The latter signifies a potential‘cost’of apical dominance.Using natural populations of 19 herbaceous angiosperm species with a conspicuously vertical,apically dominant growth form,we removed(clipped)the shoot apical meristem for replicate plants early in the growing season to test for a potential cost of apical dominance.Clipped and unclipped(control)plants had their near neighbours removed,and were harvested after flowering production had finished but before seed dispersal.Dry mass was measured separately for aboveground body size(shoots),leaves,seeds and fruits;and number of leaves,fruits and seeds per plant were counted.We predicted that:(i)our study species(because of their strong apically dominant growth form)would respond to shoot apical meristem removal with greater branching intensity,and thus overcompensation in terms of fecundity and/or biomass;and(ii)overcompensation is particularly enabled for species that produce smaller but more leaves,and hence with a larger bud bank of axillary meristems available for deployment in branching and/or fruit production.Widely variable compensatory capacities were recorded,and with no significant between-species relationship with leaf size or leafing intensity—thus indicating no generalized potential cost of apical dominance.Overall,the results point to species-specific treatment effects on meristem allocation patterns,and suggest importance for effects involving local variation in resource availability,and between-species variation in phenology,life history traits and susceptibility to herbivory.
文摘It is vital to determine the effective photoperiods of maize for making full use of tropical germplasm, which is the foundation for determining the effect of latitude and planting date on the development of photoperiod-sensitive maize cultivars. The objective of this study is to determine the photoperiod-sensitive inductive phase using reciprocal transfer between long- day （LD） （15 h d^-1） and short-day conditions （SD） （9 h d^-1）. For Huangzao 4 and CML288, days to tassel and pollen shedding were recorded, and stem apical meristems （SAM） were observed by a laser scanning confocal microscope. The results show that the seedlings are insensitive to photoperiod when they are very young （juvenile）. However, after this period, LD delays flowering and increases the leaf numbers below the inflorescence, and the length of the interval of the photoperiod-sensitive inductive phase is longer under LD conditions than under SD conditions. Transferred from SD to LD, plants show a sudden decrease in leaf numbers once sufficient SD has been received for flower commitment. While transferred from LD to SD, plants have a continuous increase in leaf numbers during the photoperiod sensitive inductive phase under LD conditions. At the same time, when plants are competent to flowers, the obvious morphology is the elongation of maize SAM. There is an obvious variance of the photoperiod sensitive phase under LD and SD conditions in different maize.
