The impact of fire on hard-coated Cistaceae (Halimium ocymoides, Cistus ladanifer, and C. salvifolius) soil seed banks in a Mediterranean 'maquis' shrubland, and its effect on seed germinability were studied. The study also contrasts the effectiveness of two widely used techniques for quantifying seed banks, the seedling emergence and the physical separation methods, in relation to fire. The null hypothesis that a massive enhancement of physically-dormant Cistaceae seed germination by fire would make use of the time-consuming physical separation technique unnecessary was tested. Fire reduced Cistaceae seed banks in the 0-2 cm deep soil layer by both seed fire consumption and lethal temperatures, revealed by the significant decreasing of the seed bank density and by the increase of apparently-intact but soft-unviable seeds, respectively. In contrast, no damage was recorded in the 2-5 cm soil layer. A dramatic seed bank depletion (> 90%) in both soil layers was recorded one year after fire in the burnt area, coinciding with a significant increase of seedling density confined to the first post-fire year. The ecological consequences of this massive post-fire seed bank input are discussed. A germinability test revealed that germination of surviving Cistaceae seeds was significantly enhanced in all cases except for the C. salvifolious seed bank in the deeper soil layer. However, final germination levels (60-75%) did not correspond to the magnitude of seed bank depletion, especially for C. salvifolious, which suggests that other environmental factors not exclusively associated with fire may also be important in softening Cistaceae seeds. Germination enhancement by fire soil-heating was not high enough to reject the physical separation technique, at least in the deeper soil layer. The simultaneous use of both seedling emergence and physical separation is recommended for reliable seed bank estimates when a physically-dormant hard-seeded component can be expected in the soil, as in many Mediterranean ecosystems, regardless of fire occurrence.

The physicochemical properties of eight hydrocarbon-contaminated soils were used to predict toxicity to earthworms (Eisenia fetida) and plants. The toxicity of these preremediated soils was assessed using earthworm avoidance, survival, and reproduction and seed germination and root growth in four plant species. No-observed-effect and 25% inhibitory concentrations were determined from the earthworm and plant assays. Physical property measurements and metals analyses of the soils were conducted. Hydrocarbon contamination was characterized by total petroleum hydrocarbons, oil and grease, and GC boiling-point distribution. Univariate and multivariate statistical methods were used to examine relationships between physical and chemical properties and biological endpoints. Soil groupings based on physicochemical properties and toxicity from cluster and principal component analyses were generally similar. Correlation analysis identified a number of significant relationships between soil parameters and toxicity that were used in univariate model development. Total petroleum hydrocarbons by gas chromatography and polars were identified as predictors of earthworm avoidance and survival and seed germination, explaining 65 to 75% of the variation in the data. Asphaltenes also explained 83% of the variation in seed germination. Gravimetric total petroleum hydrocarbons explained 40% of the variation in earthworm reproduction, whereas 43% of the variation in plant root growth was explained by asphaltenes. Multivariate one-component partial least squares models, which identified predicators similar to those identified by the univariate models, were also developed for worm avoidance and survival and seed germination and had predictive powers of 42 and 29%, respectively.

To determine the factors affecting the germination, early germ-tube growth (collectively called 'germination') of chlamydospores of Fusarium oxysporum f. sp. cubense and the severity of Fusarium wilt in banana plantlets, we varied chemical and physical factors in a suppressive and conducive soil. Soil temperature (4-40 degrees C), water content (40-80% field capacity), and pH (4-10) were varied, and various amounts of CaCO(3), Ca(OH)2 and Fe-EDDHA were added to the soils. The suppressive soil had higher populations of actinomycetes and bacteria than the conducive soil that had higher populations of filamentous fungi and yeasts. The suppressive soil reduced germination of chlamydospores by 41 +/- 4%, and more than halved disease severity in banana plantlets (Musa spp., AAA, Cavendish subgroup, cv. Williams). Soil water content, from wilting point to 80% field capacity, had little effect on germination of chlamydospores in either soil. In contrast, a water content of 40% field capacity promoted disease severity in both soils, compared with wetter soil. Increasing the temperature from 20 to 30 degrees C in the conducive soil increased chlamydospore germination by 1.9 fold, but in the suppressive soil it had a much less effect (1.2 fold increase). This indicated that a physical process, such as diffusion, is likely to limit germination in the suppressive soil. An increase in temperature from 24 to 34 degrees C increased disease severity in both suppressive and conducive soils. At 14 degrees C no wilt symptoms were evident but the pathogen was recovered from within the plant. Chlamydospore germination was greatest in both soils at their natural pH of 8. A similar pattern existed for disease severity in the conducive soil. However, in the suppressive soil pH had little effect on disease severity. Adding CaCO(3), Ca(OH)2, CaSO(4) or Fe-EDDHA to the soil reduced germination and disease severity by one-third to one-half in both soils. Smaller amounts had the greatest effect and the amounts of Ca compounds used were insufficient to change soil pH. The effects of manipulating soil pH, Ca and Fe content, temperature and water content on disease expression in the field need to be demonstrated.

Spinach (Spinacia oleracea L.) seed germination can be inhibited by high temperatures. An understanding of thermoinhibition in spinach is critical in predicting germination and emergence events. The purpose of this study was 3-fold: 1) to determine seed germination percentage and rate of spinach genotypes--'Cascade', 'ACX 5044', 'Fall Green', and 'ARK 88-354'--exposed to constant and alternating temperatures; 2) to determine the nature and extent of inhibition imposed by the pericarp; and 3) to investigate leachate and oligosaccharide involvement in thermoinhibition. Germination inhibition began at >20 degrees C constant temperature and was totally suppressed at 35 degrees C. Alternating temperatures at 30/15 degrees C (12-hour day/12-hour night) resulted in greater germination than a constant 30 degrees C. The genotype sensitivity to supraoptimal temperatures was in the order of 'ARK 88-354' less than or equal to 'Fall Green' < 'ACX 5044' < 'Cascade', but the highly thermoinhibited 'Cascade' seeds retained the ability to germinate when shifted to lower incubation temperatures. The pericarp inhibited germination, since seeds deprived of the pericarp had approximately equal to 90% germination at 30 degrees C. 'ACX 5044' and 'Cascade' had higher ABA content in the pericarp than 'ARK 88-354' and 'Fall Green'. Before imbibition at 30 degrees C, raffinose levels in each genotype were in the order of 'ARK 88-354' > 'Fall Green' > 'Cascade'. After 48 hours of imbibition, sucrose and glucose levels were highest and raffinose levels were lowest in 'ARK 88-354' and 'Fall Green' seeds, while 'Cascade' seeds remained less active metabolically. These data suggest that the pericarp apparently acts as a physical barrier as well as a source of inhibitors during thermoinhibition.

Study on physical characteristics of seed coat in relation to seed quality in soybeans was conducted with 40 lines/varieties under 2 seasons i.e. dry season 1995 and rainy season 1996 at Kasetsart University, Kamphaeng Saen Campus. The seeds were subjected to standard germination test, accelerated aging test, field emergence test, electrical conductivity test and also counted hard seed percentages. The results revealed that seed quality differed among lines/varieties. In dry season, hard seed percentages were higher than those in rainy season. The physical characteristics significantly correlated with quality i.e. seed weight, seed volume, surface area, eccentricity, seed coat percentage, seed coat thickness and seed colour. Lines/varieties with small seed, thicked-seedcoat, oblong-seed shape and seed coat with black colour gave higher quality than large seed, thin seed coat, round-seed shape and yellow colour. Path-coefficient for standard germination and field emergence of soybean in rainy season 1996 was analysed. The physical characteristics of soybean seed that showed the significant direct effects and indirect effects were seed weight, seed volume, surface area, seed gravity, eccentricity, seed coat percentage and specific weight of seed coat. The physical characteristics that showed indirect effects by other characteristics were seed weight, seed size and seed shape (eccentricity). In the study of seed coat under scanning electron mocroscope of 6 soybean varieties i.e. Chiang Mai 60, Williams, SJ 4, Utsaha A, Sukhuthai 1 (SSR DMR 34) and SSR 8502-2-2. The results revealed that Chiang Mai 60, Williams and Sukhuthai 1 (SSR DMR 34) had larger pore size comparing to SJ 4, Utsaha A and SSR 8502-2-2. Physical characteristics that plant breeders should consider for selecting varieties with high seed quality were seed size, seed coat thickness, seed shape (eccentricity) and seed colour.

The purpose of this study was to examine whether rate of tomato seed germination under non-stress, cold-stress and salt-stress conditions was under similar genetic control by identifying and comparing quantitative trait loci (QTLs) which affect germination rate under these conditions. A fast-germinating accession (LA722) of the wild tomato species Lycopersicon pimpinellifolium Jusl. and a slow-germinating cultivar (NC84173, maternal and recurrent parent) of tomato (Lycopersicon esculentum Mill.) were hybridized and BC1 and BC1S1 progeny produced. The BC1 population was used to construct a linkage map with 151 restriction fragment length polymorphism (RFLP) markers. The BC1S1 population (consisting of 119 BC1S1 families) was evaluated for germination under non-stress (control), cold-stress and salt-stress conditions and the mean time to 50% germination (T50) in each treatment was determined. Germination analyses indicated the presence of significant (P < 0.01) phenotypic correlations between T50 under control and cold stress (r = 0.71), control and salt stress (r = 0.58) and cold stress and salt stress (r = 0.67). The QTL analysis indicated the presence of genetic relationships between germination under these three conditions: a few QTLs were identified which commonly affected germination under both stress- (cold-, salt- or both) and non-stress conditions, and thus were called stress-nonspecific QTLs. A few QTLs were also identified which affected germination only under cold or salt stress and thus were called stress-specific QTLs. However, the stress-nonspecific QTLs generally exhibited larger individual effects and together accounted for a greater portion of the total phenotypic variation under each condition than the stress-specific QTLs. Whether the effects of stress-nonspecific QTLs were due to pleiotropic effects of the same genes, physical linkage of different genes, or a combination of both could not be determined in this study. The results, however, indicate that the rate of tomato seed germination under different stress and nonstress conditions is partly under the same genetic control.

The chosen physical and chemical parameters of kernels of winter wheat and winter triticale from plants infested by cereal aphid (S. avenae), thrips (Tripidae) and cereal leaf beetles (Lema sp.) were investigated. The feeding of chosen pest species decrease weight of thousand kernels and contents of albumen and amino acids. In relation to the control higher water absorbing capacity was observed. Investigated pests did not have an influence on germination power of kernels

A field survey at three cities in West Java Province to get samples of certified rice seeds from 2 producers and followed by seed quality evaluation has been conducted from May 1995 to January 1996. The purpose of the experiment was to evaluate the quality of certified rice seeds sold in West Java during marketing periods, from sampling to expiration date that lasted for 6 months. Evaluation of seed quality consisted of: physical quality, germination percentage and vigor. Vigor was evaluated with first count test and accelerated again test. Result indicated that all seed lots passed the standard of Indonesian certified rice seed (germination rate was 80 percent and moisture content was 13 percent) at time of sampling (1-3 month old seed). After 3 months of storage, quality of rice seed varied between producers and among sampling locations (seed lots). Based on the standard of certified rice seed, five of six lots from producer A and three of six lots from producer B passed the standard of certified rice seed until the expiration date. However, some of the certified seed lots showed low vigor although the germination rate was 80 percent

Study on possibility of water convolvulus seed production in Phitsanulok Province was conducted at Buengpra District, Amphoe Muang during September 1997-February 1998. It was found that seed yield (120 kg/rai) was rather low compared to the average seed yield of the country (175 kg/rai). The quality of seed was acceptable; 96.24 percent of physical purity, 12.14 percent of moisture content and 82.50 percent of germination. The total production cost per rai was 2,390 Baht. The net return per rai was 4,810 Baht when the price of seed was 60 Baht a kilogram.

A pot experiment was conducted to observe the response of maize and wheat crops to inorganic fertilizers and organic manure application on an eroded soil. Four treatments (Control, N P, FYM, and N P + FYM) were applied. Maize and wheat crops were sown during kharif 1997 and rabi 1997-98 respectively. The soils which did not receive farm yard manure (FYM), delayed germination, decreased crop growth due to poor soil physical conditions but later inorganic fertilizer application performed slightly better than the organic manure alone. Maximum increase in plant growth parameters, was also recorded in pots receiving both organic and inorganic fertilizers in case of both crops e.g. in NP+ FYM treatment, the wheat yield was 4408.3 kg per hector as compared to 3350.0 kg hector for control. Incorporation of FYM alone and along with chemical fertilizers also improved the physical characteristics of eroded soil besides increasing organic matter and nutrient contents.