Based on physiological and molecular differences associated with the germination of after-ripened and dormant caryopses and excised embryos, it has been hypothesized that various methods of after-ripening are the only treatments that facilitate the transition of dormant wild oat embryos to a non-dormant state. To further investigate this hypothesis, analytical methods were used to evaluate physical and temporal changes associated with germination and subsequent growth of after-ripened and dormant excised embryos (AR-embryos and D-embryos, respectively) induced to germinate with fructose (Fru) and/or gibberellic acid (GA). While chemical treatments of Fru, GA, and Fru + GA have little effect on the germination and short-term growth of AR-embryos, they do induce germination of D-embryos. Growth following germination of D-embryos varied according to treatment with the combination of Fru + GA inducing the greatest growth over the duration of the experiment. Even considering differences in the time to complete germination, growth of D-embryos was not comparable with that of AR-embryos. This provides physical evidence that chemical treatments induce germination without fulfilling the requirements for normal after-ripening-enhanced germination/growth, and indicates that fructose and/or gibberellic acid do not remove the dormancy-block or rate limiting step in the same manner as after-ripening.

Pot-culture experiments were conducted to evaluate the effect of ash incorporation in soil on germination and stand establishment of wheat (Triticum aestivum L.), chickpea (Cicer arietinum L.), mustard (Brassica juncea L.) and lentil (Lens esculenta Moench.) during the winter season of 1995, and rice (Oryza sativa L.) and maize (Zea mays L.) during the summer season of 1996. Ash levels tested were 0, 10%, 20%, 30% and 40% for winter-season crops, and 0, 5%, 10%, 15% and 20% for summer-season crops. Changes in soil physical and chemical characteristics due to ash addition were analyzed. Germination time, defined as the time taken for 75% germination (60% in case of mustard), and delay index, a normalized parameter, were introduced to evaluate ash-incorporation effects on germination of crops. Ash addition in soil delayed germination of crops due to the increased impedance offered by the soil matrix to germinating seeds. Rice and maize were relatively less sensitive to ash for germination than winter-season crops Mustard was most affected for germination and stand establishment. The delay index showed variations between crops as well as for ash levels within a crop.

Physical treatments on Redhaven dormant peach seeds were carried out for two succcessive years 1993 and 1994 in greenhouse and laboratories were complied to detect two superior treatments in breaking dormancy and imroving germination ability as well as subsequent seedling growth. The result indicated that the same treatments had a higher rate for consumption of certain nucleosides along with cAMP + CMP, GMP and ADP nucleotides in nucleic acids synthesis or in other metabolism processes lead to breaking seed dormancy

Red raspberry (Rubus idaeus L.) seeds germinate only after seed coats are degraded. In nature this happens slowly. Seeds from recently collected fruit (fresh to four years old) germinated only after scarification of the seed coat by 20-minute soaking in concentrated sulfuric acid. Germination was not enhanced by: (1) short-term intermittent soaking, up to 81 hours, in dilute (0.01 normal) hydrochloric acid; (2) passage through the digestive tracts of bears, coyotes, or birds; (3) physical perturbations such as nicking, mechanical scarification, repeated freezing and thawing and/or four years of exposure in the field; (4) exposure to light; (5) increased temperatures or temperature fluctuations; or (6) addition of nitrogen (ammonium nitrate, urea).

It is possible to induce the formation of epidermal meristems in the hypocotyl of non-injured and non-hormone-treated plantlets of flax, by combining various sorts of physical stimulations with a transient depletion of calcium. The characteristic times for the decrease of the tissue concentration of calcium during calcium depletion and for the recovery of the normal tissue concentration of calcium after resupplying the latter ion, are close to 1 day. The stimuli may correspond to wind or drought or even to the manipulation stress occurring when the plantlets are transferred from their germination to their growth vessel. Meristem production is increased by combining several physical stimulations. When calcium depletion is delayed relative to the application of the physical stimulation(s), the production of meristems is delayed accordingly. This means that the signal induced by the physical stimulation(s) may be stored within the plants, without apparent effect, until a calcium depletion finally allows the stored signal to take effect (formation of meristems). For storage periods of up to 8 days no loss of the potency of the stored signal was observed. A few other examples of storage of morphogenetic signals in plants have been described in the literature. The mechanism involved in signal storage is still not clearly understood. However, it seems that the sensing andlor storing of the signals require that the plant tissues are sufficiently rich in calcium, whereas the licensing of the plants for the translation of signals into the final response (meristem production) is done by a transient calcium depletion.

Glasshouse and field trials were conducted to select plant species suitable for revegetation of waste fly ash lagoons. Species which demonstrated potential for growth on fly ash or ameliorated fly ash in glasshouse trials were subsequently tested by direct seeding in situ at the Port Augusta power station in South Australia. Xero- and halophytes from the families Aizoaceae, Chenopodiaceae and Zygophyllaceae performed optimally in both sets of trials, and species most suited for revegetation and regeneration included Mesembryanthemum aitonis, M. nodiflorum, Atriplex holocarpa, A. lindleyi, A. vesicaria, Enchylaena tomentosa, Halosarcia halocnemoides, H. pergranulata, Scaevola collaris and Nitraria billardierei. A range of surface amelioration treatments for fly ash lagoons designed to overcome the chemical and physical limitations of fly ash to plant growth, and to reduce the effects of high temperatures, strong winds and low rainfall in the region were also tested. A 50-100-mm surface cover (overlay) of either local sandy topsoil or compost, stabilized with coarse organic mulch, hydromulch or erosion control fabric supported good germination and plant growth. The soil or compost overlay provided a seed bed for initial germination away from the toxic elements of the ash, while the stabilization treatment prevented wind-blown removal of both seed and seed bed, while also conferring some protection to germinating seedlings. | Manfred Jusaitis and Anne Pillman

Peanut pod wart is a new disease in Israel that causes ugly warts on the pod. The causal agent, Streptomyces sp., contaminates seed during mechanical cracking of pods. Low-volume application of 3% iodine dissolved in glacial acetic acid resulted in effective pod disinfection and reduced the surface pods microflora by 4 log orders, but this mixture causes eye irritation and has an unpleasant smell. A 4 s exposure of the pods to a butane-air flame at 740 degrees C eradicated the pathogen and even a 6 s exposure did not affect seed germination or yield. This physical treatment also reduced significantly the incidence of other feedborne fungi, e.g. Aspergillus niger and Rhizopus stolonifer, in the laboratory and in a largescale field test. Flaming enables the treatment of large quantities of pods prior to cracking.

Study on relationships between physical characteristics and quality of seed in vegetable soybean KPS 292 and grain soybean i.e. CM 60, NS 1, AGS 129, ST 1, KUSL 20004, SJ 4, SJ 1, SJ 2 and SJ 5 was conducted in early and late rainy season 1994 at Kasetsart University, Kamphaeng Saen Campus. The seeds were subjected to standard germination test, field emergence test, accelerated aging test and electrical conductivity test. The results revealed that the seeds of KPS 292 showed lower quality and deteriorated more rapidly than other varieties. Path-coefficient analyses for the relationships between the physical characteristics of soybean seed and seed quality in early rainy season showed the significant direct effects of percent embryonic axis and eccentricity (seed roundness) on the field emergence test. In late rainy season, percent seed coat and percent embryonic axis demonstrated high direct effects on field emergence test. For the 9 grain soybean varieties, percent embryonic axis and percent seed coat had direct effects on field emergence and seed dry weight had indirect effect through these 2 characters. For late rainy season, percent seed coat, seed density, seed dry weight and percent embryonic axis of the vegetable soybean KPS 292 showed direct effects on field emergence, while other grain soybeans all characters did not show significant effects on field emergence.