Flowering of Stylosanthes guianensis in Relation to Juvenility and the Long-Short Day Requirement

Seedlings of Stylosanthes guianensis var. guianensis were grownin long (14 h) days in five temperature regimes for varyingperiods before transfer to short (11 h) days at 30 ?C/21 ?C.The juvenile phase before seedlings responded to inductive conditionswas c. 45–50 d, 50–60 d and 60–70 d for cv.Schofield, cv. Cook and C.P.I. 34906 respectively, which ispositively related to their critical photoperiod for flowering.Temperatures favourable for growth (e.g. 30 ?C/26 ?C) reducedthe juvenile phase in C.P.I. 34906 and in Cook, which did notflower in 11 h days unless previously exposed to more than 18long days. In a second experiment cv. Cook was confirmed as a long-shortday plant. Seedlings were grown for 50 d in a glasshouse withnatural daylength extended to 13, 14, 16 or 24 h before transferto 12 h photoperiods. Cook floral development was positivelyrelated to daylength provenance before transfer and plants incontinuous 12 h did not flower. Shortening daylength after 48 cycles of 12 h to 11.75 h didnot result in continued floral development in Cook plants butcv. Graham plants were initiated or transitional by 75 d. Key words: Stylosanthes guianensis, Photoperiod, Temperature, Flowering     

A revised method for the application of API 50 CH carbohydrate kits to yeasts

A revised method is described for the application of the API 50 CH carbohydrate kit to yeasts. The method permits an objective assessment of positive assimilation with a high degree of reproducibility.     

Effects of temperature on the flowering and seed production of Stylosanthes guianensis cultivars

Seedlings of Stylosanthes guianensis var. guianensis were grown for 75 days in 16 h photoperiods and transferred to controlled environment cabinets for a further 112 cycles set at 12 h days and 18, 21, 24 or 27 OC constant temperatures. Floral initiation (FI) occurred in cv. Cook after 21 short-day cycles of 12 h and was independent of temperature. Warm temperatures delayed FI in cv. Schofield and hastened it in cv. Endeavour. Rate of node appearance was positively and the duration of the phase FI to flower appearance negatively related to temperature. Spike production and floret number per spike were maximal for Cook and Endeavour at 24°C; seed setting was independent of temperature above 18°C in Cook. Growth, flowering, and seed production of Endeavour required warm temperatures, but Cook was more versatile in its adaptation to varying temperature regimens.     

Determination of the carbonation tolerance of yeasts

A simple method is described for the determination of the carbonation tolerance of yeasts. Using the method, data are presented for the carbonation tolerance of some common soft drink spoilage yeasts.     

A quantitative analysis of varietal and moisture status effects on the growth of Vicia faba in relation to radiation absorption

Growth of two cultivars of Vicia faba, under various conditions of moisture status, was analysed in terms of solar radiation absorbed by their foliage. The relationship between dry-matter production and absorbed photosynthetically active radiation was linear throughout the growing season for both cultivars (Minica and Alfred) and for all levels of soil moisture status. A straight line was used, the slope of which represented a constant mean seasonal ‘efficiency’ of conversion of radiation into biomass. Moisture stress reduced both the amount of radiation intercepted, by limiting the size of the canopy, and the efficiency of its conversion into dry matter. Efficiency of both cultivars grown under optimal water regimes was similar, however, drought had a more drastic effect on conversion efficiency of Minica. Mean crop growth rates were highly dependent upon both absorption and efficiency, as were maximum crop growth rates during the linear portion of growth. Reductions in seed yield were similar to trends in total biomass production. Harvest index was reduced by moisture stress in Minica, and increased to compensate for dry-matter loss in Alfred.     

Factors contributing to the loss of seed from the seed-bank of Trifolium balansae and Trifolium resupinatum over summer

Abstract The influence of predation, fungi and germination of seed of the annual legumes Trifolium balansae and Trifolium resupinatum was investigated by placing known quantities of seed in bags in the field; combinations of all three factors were imposed. It was found that rainfall was the most important factor contributing to the loss of seed over summer (up to 76%), followed by predation (up to 15%); fungi had only a very small influence (0.1–0.2%). Predation contributed to a larger percentage of loss over summer in T. resupinatum line SA14433 than in T. balansae cv. Paradana, which is attributed to seed size. The effect of summer grazing on the size of the seed-bank was investigated. It was found that summer grazing did not influence the amount of seed present in the seed-bank in March. Removal of all surface material in December resulted in a significant drop in seed reserves compared with the ungrazed or grazed areas. Hardseededness in March was not affected by any of the treatments; the seedling density after regeneration was not affected by summer grazing, but was reduced when all surface material was removed. The data were incorporated in a model to describe seed loss from the seed bank over summer quantitatively; the utility of such models is discussed.     

Development of Floral Apex After Floral Induction in Stylo (Stylosanthes guianensis (Aubl.) Sw. var. guianensis)

The apex morphology of stylo (Stylosanthes guianensis var. guianensis)is described in four developmental phases (vegetative, transitional,initiated and floral) further subdivided into a total of tenstages. The apical dome broadens and flattens as induction proceedsuntil the initiation phase when apical diameter within 0.05mm of the dome apex is 55 per cent greater than in the vegetativeapex. Changes in vegetative morphology during induction aredescribed. Stylosanthes guianensis var. guianensis, stylo, flowering, reproductive anatomy, developmental stages     

Day and Night Temperature Control of Floral Induction in Stylosanthes guianensis var. guianensis cv. Schofield

Floral initiation in seedlings of Stylosanthes guianensis var.guianensis cv. Schofield grown at a photoperiod marginal forflowering (12–11.75 h) was promoted by a combination oflow day (25 °C) and low night (16 or 21 °C) temperatures,and completely inhibited by a 35 °C day temperature. Additionally,earliness of floral initiation under naturally decreasing daylengthwas negatively related to temperature regime over the range35/30 to 20/15 °C (day/night). Stylosanthes guianensis var, guianensis, flowering, temperature, photoperiod, short-day plant