Cassava growth and yield depend on the chemical as well as physical properties of the soil. The physical properties are determined by the inherent characteristics of the soil, but are also affected by tillage practices. This study was conducted to determine the effect of various land preparation techniques on cassava germination and yield in addition to its effect on soil physical characteristics. Cassava (Rayong 1) was planted in the early rainy season of 1991 in Sri Racha, Chonburi province and was harvested at 5, 7.5, 10 and 11 months. Six treatments consisted of: (1) no-tillage; (2) plowing; (3) plowing and harrowing; (4) plowing and harrowing followed by soil compaction; (5) plowing and harrowing followed by ridging; and (6) subsoiling. There were three replications. No differences in germination percentage due to treatments were observed. But there were significant differences in top weight and root weight between the soil compaction and various other treatments, because of excessively high bulk density, high penetrometer resistance, low water infiltration rate and low hydraulic conductivity of the compacted soil at all (3, 6, 9 and 12 months) times of measurement, both at 10 and 30 cm depth. However, for this soil with loamy sand texture, the various tillage treatments had no significant effect on cassava root yield as compared with the no-tillage treatment due to their similar effects on soil physical properties. Soil compaction was the only treatment which significantly affected both the various soil physical characteristics as well as all cassava growth parameters.

Unlike most of the hydrolytic enzymes that participate in endosperm mobilization, beta-glucosidase of barley (Hordeum vulgare) seeds does not increase during germination, even in the presence of exogenously added gibberellic acid. However, the germination process affects the physical properties of beta-glucosidase in terms of charge and apparent molecular weight. Analysis of developing barley grains shows that the enzyme is synthesized two weeks before maturation and is stored in the endosperm of the dry dormant seed. Partial amino acid sequencing of the purified beta-glucosidase demonstrates significant similarity between the barley enzyme and beta-glycosidases that belong to family 1 of glycosyl hydrolases.

Aspergillus niger (strain UUF9202) significantly reduced the dormancy period and boosted aggregate germination percentage (AGP) in seeds of Tetrapleura tetraptera. A net reduction in mean germination time (MGT) to 12 days and an increase from 0 to 42% AGP were obtained in 32 days. The optimal spore inoculum of the fungus was 8.5 X 10(10) ml(-1) per 100 seeds in 96 h pregermination incubation. The potential of some physical factors in combination with this fungal concentration in enhancing AGP was evaluated. The treatments were as follows: (i) hot water scarification at 30 degrees C, 50 degrees C, 80 degrees C and 100 degrees C plus A niger; and (ii) nicking by decoating at either the micropylar or chalazal ends plus A niger. Micropylar scarification plus A niger gave the highest AGP (94%) followed by chalazal scarification plus A niger (86%) and hot water dip at 80 degrees C + A niger (82%). The control seeds which were soaked in presterilized (by autoclaving at 121 degrees C for 15 min) A niger spore suspension at 30 degrees C gave zero germination.

1. Bryophytes played a dominating role in recolonizing bare surfaces left by severe fires which destroyed the vegetation and variable amounts of peat on parts of the North York Moors in the dry summer of 1976. Ashed peat (AH) was normally first colonised by Ceratodon purpureus, followed by Polytrichum piliferum with dominance later tending to pass to P. commune. Charred surfaces and progressively granulating peat (GP) remained largely bare except for patches of Dicranella heteromalla, Pohlia nutans and Polytrichum spp. 2. On charred surfaces recreated in this study and GP bryophyte cover was < 10% after one year, compared with 22% on ash. Shelter and lime treatments resulted in nearly 100% cover on some charred peat and ash, but superficially charred peat and GP still had < 50% cover. 3. Glasshouse trials confirmed that charred surfaces and GP had some residual chemical deficiency or toxicity even when physical conditions were improved. 4. In hanging-drop cultures, Pohlia nutans germinated well on extracts of all surface-types and Funaria hygrometrica germinated well on extracts from AH and GP; Polytrichum commune gave about 10% germination on AH, and D. heteromalla about 10% germination on AH and GP. Germination of C. purpureus on all the burnt surfaces, and of F. hygrometrica on the charred surfaces appeared to be nutrient or pH-limited. Germination of F. hygrometrica, D. heteromalla and the Polytrichum species was apparently inhibited to varying degrees by water-soluble extracts from the charred surfaces. 5. Protonema of Pohlia nutans grew well on extracts from all surfaces. D. heteromalla grew well on AH and to some extent on GP; F hygrometrica showed some growth on extracts from AH and GP. Growth of C. purpureus and D. heteromalla appeared to be nutrient- or pH-limited on some or all of the burnt surfaces. Extracts from the burnt surfaces reduced growth of F. hygrometrica and almost or completely suppressed growth of Campylopus pyriformis and the Polytrichum species. 6. The pH appeared to be an important factor affecting germination and growth for most species; there was a significant positive correlation between germination and pH of the culture solution (range 3.5-6.4) for all species but Ceratodon purpureus and Pohlia nutans. 7. In glasshouse trials, toxicity from lichen/alga crusts on intact peat surfaces reduced germination of D. heteromalla by c. 50%: the similar effect on germination of Polytrichum piliferum was not statistically significant. 8. Wind-tunnel experiments showed that the surface of charred peats and GP dried quicker than AH under high-radiation conditions. Except for Campylopus pyriformis, which survived to 390 MPa, the protonema of all the mosses was killed by 24h exposure at -23 MPa: protonema of Polytrichum commune was the most sensitive to slight desiccation. 9. Ash is chemically and physically favourable for moss establishment. Freshly charred surfaces are chemically unfavourable. Establishment on these surfaces can only occur if there is an adequate interval between amelioration of chemical conditions and the onset of physical instability and granulation of the peat surface.

It has been found that the pre-sowing electro-physical treatments with equal values of the controllable factors of action, carried out in different months of the year, affect in different ways the cotton seed properties. The selected values of the controllable factors produce a positive effect from the treatment (an increase in the germination capacity of the seeds and cotton yield growth) when it is conducted in the first ten days of April.

The stability and maturity of compost prepared from municipal solid waste (MSW) at a full-scale composting plant was assessed through chemical, physical, and biological assays. Respiration bioassays used to determine stability (O₂ and CO₂ respirometry) were sensitive to process control problems at the composting plant and indicated increasing stability with time. Radish (Raphanus sativus L.) and ryegrass (Lolium perenne L.) growth bioassays revealed that immature compost samples inhibited growth. Growth of ryegrass in poring mix prepared with cured compost not amended with fertilizer was enhanced as compared to a peat control. Garden cress (Lepidium sativum L.) seed germination, used as an indicator of phytotoxicity, revealed inhibition of germination at all compost maturity levels. The phytotoxicity was thought to be salt-related. Spearman rank-order correlations demonstrated that 0₂ respirometry, water-soluble organic C, and the water extract organic C to organic N ratio, significantly correlated with compost age and best indicated an acceptable level of stability. Oxygen respirometry also best predicted the potential for ryegrass growth, and an acceptable level of compost maturity.

Corn at 30% moisture was air-dried at 25-100 degree C. Drying times to 12% final moisture ranged from 1 hr at 100 degree C to 38 hr at 25 degree C. Chemical composition was unchanged by drying temperature. Increasing drying temperature decreased test weight, germination, nitrogen solubility index, and it increased kernel breakage susceptibility and percentage of floating kernels. Because breakage susceptibility, but not stress-cracking, increased upon high-temperature drying, some chemical or physical change other than stress-cracking in the kernel cell-wall matrix or in the starch granules may have affected breakage susceptibility. Isoelectric focusing showed decreasing protein bands at pi 4.0-6.6 as corn-drying temperature increased from 70 to 100 degree C. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that proteins with molecular weights of 21,000-97,000 decreased after treatment at 70 degree C; they cannot be observed in corn dried at 85-100 degree C. Prolamin levels also decreased as air-drying temperature increased. Thus, corn density, breakage susceptibility, and germination may change upon drying because of changes in albumins and prolamins. These relationships may provide new or improved methods for identifying grain that is damaged or of lower quality due to high-temperature drying.

Small scale farmers use vegetative barriers (live fences) because they are found to be cheap and easily manageable. The cholla cactus (Opuntia exaltata) is a barrier that is commonly used as a live fence. In order to gain a better understanding of the growth and use of the cholla cactus as a wildlife barrier, an investigation was conducted in 3 areas namely Nakuru, Laikipia and Taita Taveta districts. The study was conducted with the following objectives: 1. To conduct a survey in Nakuru, Laikipia and Taita Taveta districts to determine the methods of planting, problems and use of cholla cactus as a live barrier, 2. To investigate the physical and chemical characteristics of soil on the growth and height of the cholla cactus in the 2 main areas: Naivasha (Nakuru district) and Laikipia district, 3. To determine the viability and germination of cholla seeds.

Non-Peer Reviewed | Producers in the Canadian Prairies are increasingly adopting conservation tillage systems. A large part of the success of conservation tillage rests on the availability of equipment able to seed into standing stubble. In semiarid environments, wheat yields are often limited by poor stand establishment and low plant density. Consequently, furrow openers and packing systems that promote complete and rapid germination and emergence improve the odds of obtaining good yields. A series of field studies are being conducted at Swift Current to develop protocols for the evaluation of furrow openers and packing systems for reduced tillage systems. The testing protocol consisted of a number of measurements to evaluate the physical properties of the soil within the furrow (bulk density,aggregate size distribution, penetration resistance), estimators of the shape and conformation of the furrow (volume of soil disturbed by the opener, perimeter length, surface roughness, measurement of water status of the soil surrounding the seed (volumetric water content and evaporation rate) estimators of seedling emergence and speed of emergence, measurements of aboveground biomass accumulation by the plants up to the 3 leaf stage, and measurements of the depth of seeding and dispersion of seeds in the furrow area. This presentation will discuss the merits and limitations of the protocol based on the results of an exploratory test of a number of furrow opener-packer combinations.

Previous studies suggested that the CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) gene product represses photomorphogenic development in darkness and that light signals reverse this action. In this report, we used genetic analysis to investigate the regulatory hierarchical relationship of COP1 and the loci encoding the photoreceptors and other signaling components. Our results showed that cop1 mutations are epistatic to the long hypocotyl mutations hy1, hy2, hy3, and hy4, suggesting that COP1 acts downstream of the phytochromes and a blue light receptor. Although epistasis of a putative null cop1-5 mutation over a hy5 mutation implied that COP1 acts downstream of HY5, the same hy5 mutation can suppress the dark photomorphogenic phenotypes (including hypocotyl elongation and cotyledon cellular differentiation) of the weak cop1-6 mutation. This, and other allele-specific interactions between COP1 and HY5, may suggest direct physical contact of their gene products. In addition, the synthetic lethality of the weak deetiolated1 (det1) and cop1 mutations and the fact that the cop1-6 mutation is epistatic to the det1-1 mutation with respect to light control of seed germination and dark-adaptative gene expression suggested that DET1 and COP1 may act in the same pathway, with COP1 being downstream. These results, together with previous epistasis studies, support models in which light signals, once perceived by different photoreceptors, converge downstream and act through a common cascade(s) of regulatory steps, as defined by DET1, HY5, COP1, and likely others, to derepress photomorphogenic development.