High synchrony, rate, and germination of needle palm [Rhapidophyllum hystrix (Pursh) H.A. Wendle & Drude] seeds were achieved only after removing the sclerotesta and embryo cap, which imposed physical dormancy. After scarification, recently harvested seeds or seeds stored for 12 months at 5C and 100% relative humidity had 96% and 98% final germination (G), with 9 to 11 days required to achieve 50% of final germination (T50) at 30C. Germination temperature controlled G, T50, and days between 10% and 90% of final germination (T90-T10) of scarified seeds, with respective values of 98%, 9 days, and 5 days at 30C, and 18%, 31 days, and 12 days at 15C. Seeds with 36% moisture at harvest had no reduction in G until moisture was <14%. Germination of seeds with 19% moisture declined from 80% if stored at 0C to 33% if stored at -10C; no seeds germinated after storage at less than -10C.

High synchrony, rate, and germination of needle palm [Rhapidophyllum hystrix (Pursh) H.A. Wendle and Drude] seeds were achieved only after removing the sclerotesta and embryo cap, which imposed physical dormancy. After scarification, recently harvested seeds or seeds stored for 12 months at 5C and 100% relative humidity had 96% and 98% final germination (G), with 9 to 11 days required to achieve 50% of final germination (T50) at 30C. Germination temperature controlled G, T50, and days between 10% and 90% of final germination (T90-T10) of scarified seeds, with respective values of 98%, 9 days, and 5 days at 30C, and 18%, 31 days, and 12 days at 15C. Seeds with 36% moisture at harvest had no reduction in G until moisture was <14%. Germination of seeds with 19% moisture declined from 80% if stored at 0C to 33% if stored at -10C; no seeds germinated after storage at less than -10C.

Experiments were undertaken to investigate various physical attributes of lentils and to identify physical factors contributing to the quality of lentil and management during harvest, drying and storage. Most of the physical properties of lentil seeds examined, including dimension, density, seed breakage susceptibility, resistance to airflow and specific heat, were affected by moisture content. Field experiments revealed that swathing and chemical desiccation were effective means of reducing seed moisture content. However, artificial drying is still necessary when wet weather prevails for prolonged periods. Moisture content is the most dominant factor in harvest management. To avoid extensive mechanical damage, the crop should be harvested when the seed moisture content ranges from 14 to 20 (wet basis). In artificial drying, the temperature should be kept below 70 to prevent seed browning and loss of germination

Three naturalized grass species widely distributed in the Dominio humedo de Chile were collected and characterized. They correspond to Agrostis tenuis, Holcus lanatus and Bromus unioloides. Vegetative tillers were transplanted into experimental plots to study phenologic development, seed germination and seedling vigour. Physical features of the seed such as size, weight and viability were also determined. The germination test was carried out under controlled conditions of temperature, light and moisture. The test lasted between 14 and 28 days in accordance with the requirements of each species. Simultaneously, the effect of two pregerminative treatments (precooling of seeds at 4 for 7 days and a 0,5% solution of potassium nitrate at the substrate) were tested. Bromus unioloides showed the greater percentage of germination (greater than 95%), and seedling development throughout the germinative process. Agrostis tenuis presented the smaller percentage of germination (50% as average) and a high percentage of latent seeds. Holcus lanatus showed an intermediate performance reaching a final germination great then 75% and a low percentage of latent seeds. Only the pregerminative treatment with potassium nitrate had significant effect upon the germination of Agrostis tenuis. The seedling vigour study lasted for 62 days. Growth and development of the three species was compared with Dactylis glomerata, as control. At the end of the period, the accumulation of dry matter in leaves and roots, and the lamina/sheath ratio were measured. Bromus unioloides showed the greater growth rate, expressed as dry weight of leaves and roots per plant per day. Agrostis tenuis showed the smallest growth rate, but with a better lamina/sheath ratio

Over the past century woody plants have increased in abundance on sites formerly occupied by grasslands in the Sonoran Desert. Woody plant invasion has been associated with a multitude of biological and physical factors. This study was conducted to determine temperature, soil, fire, rodent, and livestock effects on the germination and establishment of whitethorn acacia (Acacia constricta Benth.) and velvet mesquite (Prosopis velutina (Woot.) Sarg.). Optimum termination temperatures for both shrubs ranged from 26 to 31 degrees C, and seedling emergence was greatest from seed sown at 1 to 2 cm depths in sandy loam soil. Merriams kangaroo rats (Dipodomys merriami) fed seeds in the laboratory removed seed coats and planted embryos at 2 to 4 cm depths in a sandy loam soil. Prescribed fire killed 100% of seed placed on the soil surface but had no measurable effect on the germination of seed planted at 2 cm. After passage by sheep, about 6% of the A. constricta and 13% of the P. velutina seeds germinated while after passage by cattle, only 1% of the A. constricta and 3% of the P. velutina seed terminated. Embryo planting by rodents may improve survival efficiencies for these legunminous shrub seedlings, but seed consumption and passage by sheep and cattle appear to adversely affect seed germination. Dipodomys merriami, rather than domestic livestock, may be responsible for the spread of these shrubs in the Sonoran Desert.

En este trabajo se pone de manifiesto la aptitud de los residuos de la industria del corcho como sustrato, alternativo a la turba rubia, para el cultivo de diversas especies vegetales. Se consideran y discuten los resultados obtenidos en diferentes ensayos, tras cuatro años de trabajo en esta línea, que han permitido caracterizar el producto desde el punto de vista físico, químico y biológico, así como realizar un seguimiento de los procesos de germinación, enraizamiento y" desarrollo de distintas plantas, en dicho residuo. | It has been studied the waste of the cork industry as a new horticultural substrat. Results about physical, chemical and biological analyses of cork are presented. Also it has been studied germination, rooting and growth of different horticultural and ornamental plants on cork as potting media.

Survey on the quality of mungbean and soybean seed used by farmers in some areas of Phitsanulok province in dry season 1989/90 was found that 5 out of 15 of the seed samples were poor in quality which were lower than the minimum standard set forth in the seed legislations. Three out of 8 of the mungbean seed samples contained bruchids resulting in reduced seed germination from 75-91 percent to 21-45 percent within 3 months. 2 out of 3 of the soybean seed samples should not be used as planting materials and 2 out of 4 samples of blackgram were low in physical purity. Most of the farmers on this area normally keep their own seeds from the previous harvest or purhase from the local dealers.

Pasture improvement of the Ragusa plateau requires establishment of desirable forage species from seeds. In particular, the germination and establishment of legume species can be limited by seed dormancy due to hard seeds, or impermeability of the seed coats to water. Experiments were conducted to identify the factors which determine this dormancy and the actions required to remove it. Seeds of the two annual leguminous species (Medicago ciliaris (L.) All. and Medicago rugosa Desr. were exposed to several mechanical (scarification by hand and within a scarifier), physical (high temperature in hot water or ultra-low temperature in liquid nitrogen) and chemical (sulfuric acid) treatments being the most effective in breaking dormancy. Scanning electron microscopy of the seed coats of the two species indicated that the differences in responsiveness to the treatments may be related to the Malpighian cell layer of the seed coat, which was thicker in M. ciliaris (82.3 micron)

Numerous areas of biological research (e.g., control of seed dormancy and protein synthesis, and development of cell-free translation systems) are greatly aided by the use of large quantities of viable cereal embryos. The utility of a method that employs a commercial food blender for embryo isolation was assessed for mature caryopses of various grain lots of wheat (Triticum aestivum L. em Thell.), rye (Secale cereale L.), triticale (× Triticosecale Wittmack), barley (Hordeum vulgare L.), oat (Avena saliva L.), rice (Oryza saliva L.), pearl millet [Penniselum glaucum (L.) R. Br.], grain sorghum [Sorghum bicolor (L.) Moench.], and maize (Zea mays L.). The yield, physical condition, and morphology of embryos and embryonic axes were characterized using light and scanning electron microscopy. Viability of embryonic axes was assessed by germination assay. Intact embryonic axes free of damage and adhering tissues (i.e., scutellum and pericarp) were easily isolated from wheat, rye, triticale, and oat. The highest yield was obtained with wheat (≈10–15%). In hulless barley, pericarp always remained attached and covered the radicle portion of the embryonic axis. Embryonic axis isolation from hulled barley was poor. Rice embryos with adhering scutellum and pericarp were isolated as a unit with 2% yield, similar to rye, triticale, and oat. Intact axes of millet, sorghum, and maize were isolated infrequently and with difficulty. Viability of embryonic axes selected visually for intactness and lack of physical damage was similar to the viability of the parent grain lot.

A unique nuclease is released by Fusarium solani f. spp. pisi and phaseoli macroconidia during germination on pea pod endocarp tissue. This Fsp nuclease is produced in greater amounts by macroconidia germinating on pea pods than in Vogel's rich medium or in water. We have characterized the enzymatic activities, and physical properties of this enzyme. Fsp nuclease makes randomly situated single stranded nicks in single- or double-stranded DNA, leaving a 5' phosphate group and a 3' hydroxyl group on the nicked DNA strand. This nicking activity is stimulated by divalent cations over a range of 2-10 mM, with Mn2+ > Ca2+ > Co2+ > Mg2+. Zinc inhibited the nuclease, even in the presence of stimulatory divalent cations. Fsp nuclease is susceptible to treatment with proteinase K or SDS, indicating a proteinaceous identity, but surprisingly, is resistant to boiling. A 22 kDa molecular weight was estimated by renaturing the enzyme following denaturing electrophoresis. The possible role of this nuclease in virulence is being investigated.