The effect of Achene heteromorphism on progeny traits in the shaggy soldier [Galinsoga ciliata (Rafin) S. F. Blake]

Abstract

A b s t r a c tThe shaggy soldier [Galinsoga ciliata (Rafin) S. F. Blake], family Asteraceae] is an invasive species that poses a growing threat to crop production. This annual plant produces heteromorphic achenes in a capitulum type inflorescence. The objective of this study was to compare selected morphological and phenological parameters and the success of generative reproduction in plants developed from peripheral and central achenes of the capitulum. The somatic variability of G. ciliata diaspores contributed to differences in the growth rates, development and fertility of the resulting populations. The progeny of central diaspores developed at a slower rate than the individuals derived from peripheral achenes, but at the end of their life cycle, the offspring of dimorphic achenes formed homogenous groups as regards height values. On average, the initial phenophases of G. ciliata plants derived from central achenes began one day later, and they entered the flowering stage eight days later than the individuals developed from peripheral seeds. At the initial growth stage (experimental day 65 to 83), the progeny of central achenes produced fewer capitula. On day 133, the individual fertility of the plants derived from central diaspores was 10% higher on average in comparison with the offspring of peripheral achenes.

Comparative Anatomy of Ovules in Galinsoga, Solidago and Ratibida (Asteraceae)

“…The success of Galinsoga is most probably associated with its extremely efficient reproduction; even 8 to 9 weekold plant can produce 3,000 flower heads and a huge number of seeds, up to over 7,000 (Kagima, 2000). Galinsoga is also a very flexible weed because it produces heteromorphic achenes in a capitulum-type inflorescence, which probably supports survival under variable environmental conditions (Kucewicz et al, 2010). Galinsoga species occupy fields, gardens, railways and ruderal sites and may also invade seminatural habitats such as forest paths, clearings and margins in woodlands (Tokarska-Guzik, 2003Chmura, 2004;Kabuce and Priede, 2010a;Trzcińska-Tacik et al, 2010).…”

Influence of achene heteromorphism on life-cycle traits in the annual weed gallant soldier (Galinsoga parviflora Cav.)

“…In other species, Crepis aspera, C. sancta, Galinsoga ciliata, no differences in height and/or in reproductive ability were observed between the offspring of various morph types (El Keblawy, 2003;Imbert et al, 1996;Kucewicz et al, 2010). Several studies have shown that the morphological and phenological differences between plants raised from different morphs are manifested at various stages of life (El Keblawy, 2003;Kucewicz et al, 2010;Ruiz De Clavijo, 2001).…”

“…Like G. parviflora, the adult plants of Crepis aspera and Galinsoga ciliata (shaggy soldier) from different morph types showed no difference in their height (El Keblawy, 2003;Kucewicz et al, 2010). However, individuals of G. ciliata from dimorphic achenes developed at different rates, but formed homogeneous groups as regards height values at the end of their life cycle (Kucewicz et al, 2010 between individuals from peripheral and central achenes were found in Hedypnois cretica and Bidens pilosa (El Keblawy, 2003;Forsyth and Brown, 1982). Plant height is a very variable feature of individuals and is regarded as a measure of living conditions of plant populations (Moles et al, 2009).…”

“…Plant height is a very variable feature of individuals and is regarded as a measure of living conditions of plant populations (Moles et al, 2009). The diversity of architecture, and thus the differentiation of G. ciliata offspring from different morphs (Kucewicz et al, 2010), allows better use of natural resources such as space and light. Both Galinsoga species are invasive and harmful to crops.…”

“…There are also species where differences between the seedlings of heteromorphic seeds have not been reported (Brändel, 2007;Van Mölken et al, 2005), or differences in the initial period of growth are leveled at the adult stage (Ruiz De Clavijo, 2001). Morphological traits (growth rates, height, leaves, rootstock diameter, and biomass), reproductive effort and phenological parameters have been analyzed at different developmental stages of plants raised from heteromorphic achenes (El Keblawy, 2003;Forsyth and Brown, 1982;Imbert et al, 1996;Kucewicz et al, 2010;Ruiz De Clavijo, 2001, 2005. However, these studies focused on divergent traits.…”