Germination success under different treatments and pod sowing depths in six legume species present in olive groves

Abstract

This study analysed the germination success of pods of six annual native legumes species: Astragalus hamosus, Medicago minima, Medicago orbicularis, Medicago polymorpha, Medicago rigidula and Scorpiurus muricatus. The use of these species has been proposed as a means of generating and improving herbaceous cover in olive groves. Germination success was studied in terms of the variability in the number of seeds germinated per pod after 18 months at two different sowing depths, on the surface (S) and buried 10 mm (B). Pods were subject to five different pre-germination treatments: chemical scarification, consisting of immersion in sulphuric acid for 15 min (S_15) and 20 min (S_20), immersion in water for 48 h (W_48), pod precooled to -18ºC for one month (P_18º) and untreated pods (Con). The results showed that the effectiveness of the different treatments and sowing depths depended on the species, and that there were no problems of 'sibling-competition' in any of the treatments or at any of the sowing depths. Species with larger, non-spiralled pods, such as A. hamosus or S. muricatus, or with very loosely spiralled pods such as M. orbicularis, had greater germination rates when buried, mainly in the case of untreated pods and pods that were immersed in sulphuric acid for 20 minutes.Additional keywords: burial depth; spontaneous cover; scarification Abbreviations used: B (buried); Con (untreated pods); Dmax (maximum diameter); GEE (generalized estimating equations); GS/P (germinated seeds per pod); P_-18° (precooled to -18 °C for one month); S (surface sowing); S_15 (soaking pods in 95% concentrated sulphuric acid solution for 15 min); S_20 (soaking pods in 95% concentrated sulphuric acid solution for 20 min); SPE (seed production efficiency); SPP (seed production potential); W_48 (soaking pods in distilled water for 48 h).

The suitability of native flowers as pollen sources for Chrysoperla lucasina (Neuroptera: Chrysopidae)

“…Although several grass and wildflower seed mixtures are currently available to farmers to increase arthropod abundance and diversity [ 15 ], commercial seed mixtures are less adapted to Mediterranean climates [ 23 , 24 ]. The use of native species could have a beneficial impact on ground cover while avoiding the disadvantages of non-native plant species [ 24 – 27 ]. Thus, knowledge of the ways in which different native plant species attract natural enemies and pollinators and of how their floral resources are used could contribute to the development of more effective mixtures and to the promotion of effective landscape management practices [ 28 – 31 ].…”

Attraction of green lacewings (Neuroptera: Chrysopidae) to native plants used as ground cover in woody Mediterranean agroecosystems

“…There is a great diversity of native plant 69 species which are adapted to the climate conditions of orchards (Castroviejo, 1986-70 2012), and the use of native species is a novel strategy to ensure the success of ground 71 cover restoration for crops. In addition, sowing these conservation seed mixes could 72 help to establish and maintain seed banks without the need for re-sowing and defend 73 against invasion by non-native species and to reduce farming costs (Araj and Wratten,74 2015; Siles et al, 2017). Additionally, regional native species contribute to increasing .…”