EVALUATION OF TWO METHODS OF GERMPLASM COLLECTION IN MEXICO SOUTHEAST

The implementation of good farming practices in seed collecting is fundamental key to guarantee the physiological and genetic quality of forest seeds. The objective of this work was to evaluate the implementation of two methods to collect seedsfrom Cedrelaodorata L.toguarantee seeds of high physiologicalquality. Seeds from 40 superior phenotypically trees of Cedrelaodorata L. in Yucatan Mexico peninsula region were collected from March to May 2019.The collect methods applied in this research werethe traditionalcollectand the climb trees. The physiological quality of seeds wasevaluated by germination and tetrazolium test. The laboratory analysis confirmed 88% of seeds pure with 94% of germination in climbing trees method, in contrast in the traditional method showed 66% of seeds pure with 72% of germination. The results by conventional germination it was not showed significative statistical differences. These results are part of novel contributions in collectmethodology using tools to climb on trees which to be complement of superior phenotypically trees selection, contribute comprehensively to obtain physiological and genetic quality forest seeds.

Investigation of two native Australian perennial forage legumes for their potential use in agriculture: Indigofera australis subsp. hesperia and Glycyrrhiza acanthocarpa

In order to investigate the potential for domestication of native pasture legumes, a seed collecting mission was undertaken between Kalbarri and Esperance in the south of Western Australia followed by establishment of a field nursery at Northam, Western Australia. Indigofera australis subsp. hesperia Peter G.Wilson & Rowe was collected from eight sites, Indigofera brevidens Benth. from one site, and Glycyrrhiza acanthocarpa (Lindl.) J.M.Black from six sites. The field nursery was an irrigated, replicated trial designed to produce seed for future field testing and to provide preliminary information on plant agronomic characteristics. Over 12 months, I. australis produced herbage dry matter (DM) of 2.1–4.4 t/ha compared with 3.4 t/ha for a composite line of tedera (Bituminaria bituminosa C.H. Stirton vars. albomarginata and crassiuscula) and 1.0 t/ha DM for G. acanthocarpa. Most lines had digestibility and crude protein (15–25%) values that would support moderate growth of sheep or cattle. The best line of G. acanthocarpa produced >400 kg/ha of seeds, whereas I. australis had poor production most likely due to poor adaptation to the nursery site. The severity of cutting of I. australis plants had no significant effect on visual assessments of herbage growth. Most plants of I. australis died within 3 years, whereas most plants of G. acanthocarpa, I. brevidens and tedera survived for 3 years. Both I. australis and G. acanthocarpa have potential for use in broadacre agriculture as grazing plants, most likely in niches specifically suited to each, and demonstrate that native plants can contribute to pasture production currently dominated by exotic species.

Acid and Temperature Treatments Result in Increased Germination of Seeds of Three Fescue Species

Efficient germination of fescue seeds is essential for successful establishment of meadows and pastures. This research was conducted to ascertain the effects of various acid and temperature treatments on seed germination in three fescue species: Festuca rubra, F. ovina, and F. pratensis. Seeds from different cultivars, populations, or lots were exposed either to four concentrations of sulfuric acid at three different time intervals (12 treatments) or six different temperatures at three different time intervals (18 treatments). Despite all belonging to the genus Festuca, the seed from different species responded differently to the treatments. The three optimum treatments for F. rubra seed involved soaking in a 75% solution of sulfuric acid for 20 minutes (improved the germination rate by 19%), soaking in a 50% solution of sulfuric acid for 30 minutes (improved the germination rate by 18%) and exposure to either 60°C or 70°C for 90 minutes (improved the germination rate by 17%). For F. ovina seed, optimal treatments included soaking seeds for either 10 or 20 minutes in a 50% sulfuric acid solution (both treatments improved germination rates by 13%) or exposing seeds for 30 minutes in a 25% sulfuric acid solution and 80°C for 60 minutes (improved germination rate by 12%). Two optimal treatments were identified for F. pratensis seed. Whereas the first involved soaking the seeds in a 75% sulfuric acid solution for 30 minutes (improved germination rates by 22%), the second involved either exposing the seeds to 90°C for 90 or 60 minutes, or exposing the seeds to 80°C for 90 minutes (improved germination rate by 21%). Our findings indicate that if fescue seed is to be sown during the autumn (two to three months after seed collecting), treating it with acid and temperature can significantly enhance its germination.

Response of Sorghum halepense L. (Pers.) populations to nicosulfuron, rimsulfuron and prosulfuron+primsulfuron-methyl

The effects of herbicides nicosulfuron, rimsulfuron and prosulfuron+primsulfuronmethyl on eight populations of Sorghum halepense L. (Pers.) under controlled conditions were investigated. The herbicides were applied at different rates (0x; 0,5x; 1x; 1,5x; 2x; 3x recommended application rate for field use) when plants reached the height of 20-25 cm. The parameters measured seven days after treatment were leaf surface and fresh and dry mass of plants; the obtained results were then used for ED50 calculations. The response of Sorghum halepense populations to nicosulfuron, rimsulfuron and prosulfuron+primsulfuron-methyl varied from population to population, and depending on the applied rate and the measured parameter. Resistance development was not observed in any of the populations that survived herbicide treatment before seed collecting. Only the population P2 showed somewhat decreased susceptibility to nicosulfuron, which can be regarded as an early stage of resistance development.

Seed quality for conservation is critically affected by pre-storage factors

The quality of seed-conservation collections, and hence their value for species reintroduction or restoration, is critically dependent on factors operating in the period between the point of collection and arrival at environmentally controlled processing and storage facilities. The timing of the acquisition of desiccation tolerance and seed longevity in air-dry storage, in relation to mass maturity and the time of natural seed dispersal, varies across species. In some wild plant species, seed quality continues to improve up to, and possibly beyond, the point of dispersal. Holding immature berries of Solanum dulcamara L. and capsules of Digitalis purpurea L. under natural conditions enabled comparison of seed quality between seeds stored under natural conditions and those dried rapidly under seedbank dry-room conditions. While seeds from fully ripe (post-mature) capsules of D. purpurea were insensitive to different post-harvest drying treatments, seed quality declined when mature berries of S. dulcamara were held under natural conditions. These results emphasise that the selection of post-harvest treatment will not only depend on the maturity of collected seeds but also may vary across species depending on the fruit type. Except for subtropical and tropical coastal locations, ambient daytime conditions during the main seed-collecting season (November–February) across Australia can be expected to result in tolerable rates of seed deterioration for the duration of seed-collecting missions. However, because seed moisture levels can be considerably higher than when equilibrated with ambient relative humidity, post-harvest handling decisions should ideally be informed by measurements of seed moisture at the time of collection, and subsequently seed moisture should be monitored during transit.