Astragalus is the largest genus of seed plants with 3000 or more species that occurs naturally on several continents. The genus has some use as a forage and medicine and in industry, and many of the species are rare endemics threatened with extinction. The seeds are reported to be dormant at maturity, and various treatments have been used in an attempt to germinate them. Our primary aim was to determine via a meta-analysis the most effective way(s) to break dormancy in seeds of this species-rich genus. Mechanical and chemical (conc. sulphuric acid) scarification were by far the best of 12 treatments for breaking seed dormancy of the 40 species included in our meta-analysis, whereas prechilling, gibberellin and smoke were ineffective. These results along with those of imbibition tests confirm that seeds of the examined Astragalus species have physical dormancy (PY). Further, PY in these 40 species and (its documented occurrence) in 118 species that could not be included in our meta-analysis transcends climatic and geographic boundaries, edaphic conditions, life cycle/life form types and infrageneric phylogeny. Thus, it seems likely that most species of Astragalus have PY. However, in addition to PY, physiological dormancy (PD), that is, combinational dormancy (PY + PD), has been reported in a few species of Astragalus. This study should be useful to both basic and applied scientists who want to germinate seeds of Astragalus.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/F3DCEB9EBE08E931AE1987701CA6FA25/S0960258520000318a.pdf/div-class-title-a-meta-analysis-of-the-effects-of-treatments-used-to-break-dormancy-in-seeds-of-the-megagenus-span-class-italic-astragalus-span-fabaceae-div.pdf

A meta-analysis of the effects of treatments used to break dormancy in seeds of the megagenus Astragalus (Fabaceae)

One of the fundamental difficulties in Iranian rangelands is the existence of wide area of poor condition rangelands that their grazing capability is low due to continuous livestock grazing pressure. Astragalus flexilipes is one of the palatable plant species of rangelands in Iran, while its distribution is being decreased due to improper grazing. The aim of this study was to evaluation the sowing season and cultivation methods of Astragalus flexilipes in dryland farming using split plot design based on completely randomized block with three replications in Meleh-Kabud, Gahvareh, Kermanshah, Iran over two years of 2016-17. The first factor was sowing seasons (spring and autumn) and the second one was cultivation methods (row sowing and scatter sowing). Data were collected for seedling emergence, survivor rate and growth condition in the second year. Result showed significant effect of cultivation method on seedling emergence and survival rate and significant effect of sowing date on growth condition (P<0.01). The sowing date by cultivation method interaction was significant for seedling emergence and survival rate (p<0.05). The highest values of the latter traits were obtained in spring season coupled with row cultivation method. In autumn sowing the highest growth scores of 3.74 and 3.15 (out of 5) for row sowing and scatter sowing, respectively. It was concluded that the highest establishment was achieved in spring cultivation, but the vigorous plants was observed in the autumn cultivation. Thus, early spring cultivation of Astragalus flexilipes using row-sowing method was recommended for rehabilitation of the poor condition rangeland in similar climate area having relatively lower temperature.

http://www.rangeland.ir/article_671694_16bf7760cea9fb0046c4130b6048d13e.pdf

Effects of Sowing Season and Cultivation Methods on Seedling Emergence, Survivor Rate and Growth of Astragalus flexilepes L. in Rangelands of Kermanshah Province, Iran

The species Astragalus podolobus is one of the endemic species of winter pastures that grows in arid and semi-arid areas in the north of Gonbad-e Kavous. To investigate effective methods of breaking seed dormancy of Astragalus podolobus, an experiment was carried out in the framework of a completely randomized design with 15 treatments and 3 replications. Treatments included controls, 98% sulfuric acid, dry chilling for 10 and 15 days, wet chilling for 10 and 15 days, and boiling water 1, 3, 5, 10 and 15 minute, respectively. Analysis of variance showed that the percentage and speed of germination were significant in different groups while the average time of germination in different treatments was not significant. The results of comparing mean values showed that the percentage and the speed of germination in boiling water treatments were best in comparison with other treatments with significant differences. The results of this experiment also showed that reducing the exposure time of seeds to boiling water increases the germination percentage and speed, consequently, the highest percentage and speed of germination was observed in boiling water 1 minute. Boiling water 1 minute treatment can increase the germination percentage up to 47% and the seed germination speed from 0.43 to 3.09 seeds per day.

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Razavi Seyed Hadi

Papers

Planting methods effect on Astragalus cyclophyllon establishment.