The occurrence of Microsporon gypseum (Bodin, Guiart & Grigorakis) in soil nematodes
The author gives a brief survey on the prevailing statements of today's soil biology on the occurrence of nematodes in soils, further on their conditions of living and on those of the rapacious fungi as well. On the basis of his own investigations carried out mainly in garden soils of the Hungarian Plain being dressed and undressed with manure, he comes to the conclusion that the occurrence ofM. gypseum cultured by means of the To-Ka-Va method, and on the presence of the nematodes in the soil admit the assumption that the frequent infection of persons engaged in gardening which is generally caused byM. gypseum, is likely to be in correlation with the abundance of nematodes in these soils.
Some Hyphomycetes that Prey on Free-Living Terricolous Nematodes
In several preliminary summaries (12, 13, 14) published a few years ago, were set forth synoptical ly the morphological features of 16 fungi observed to subsist by the capture of free-living nematodes infesting old agar plate cultures started from various decaying plant materials. Little attention was then given to the relationships of the different fungi to species previously described, only one among them, the widely familiar and well characterized Arthrobotrys oligosfora Fres., whose predacious behavior had been impressively recorded by Zopf (72) nearly a half century earlier, being mentioned by name. In a subsequent paper (15), consideration of special organs developed by nematode-capturing ftmgi entailed identification of two other of the 16 forms; one being recognized as Dactylaria Candida (Nees) Sacc, the other as Dactylella ellipsospora Grove. The remaining 13 fungi, with the exception of two species belonging in the Phycomycetes, could be referred to (16, 18, 20) only rather cumbersomely as members of an interrelated series of Hyphomycetes distributed in large part among the genera Trichotkecitim, Arthrobotrys, Dactylella (including Monacrosporium), Dactylaria and Pcdilospora. Although some of the mucedinous forms known to capture nematodes are dealt with under established binomials, usage regarding these binomials has not always been consistent. The
Temperature effects on lily development rate and morphology from the visible bud stage until anthesis.
Day (DT) and night temperatures (NT) influenced Lilium longiflorum Thunb. 'Nellie White' stem elongation and development rate from the visible bud stage (VB) until anthesis. Plant height increase after VB was a function of the difference (DIF) between DT and NT (DT-NT). Plant height increased 90% as DIF increased from - 16 to 16C. A cubic model described bud development rate as a function of temperature from 14 to 30C. A linear model adequately described bud development rate as a function of average daily temperature from 14 to 21C. Based on the linear model, bud development rate increased 0.05 per day for each 1C increase in average daily temperature. The base temperature for bud development, i.e., the temperature at which bud development rate was 0, was calculated as 3.5C. Greenhouse forcing of vernalized Easter lilies is commonly divided into three phases: I) placement of vernalized bulbs in the greenhouse to flower initiation, II) flower initiation to VB, and III) VB to anthesis (De Hertogh and Wilkins, 1971). Plant morphological development differs during each of the forcing phases (De Hertogh and Wilkins, 1971). Growth during phase I is vegetative and consists of stem elongation and leaf expan- sion. Flower initiation, leaf expansion, and stem elongation oc- cur during phase II. Inflorescence expansion and stem elongation occur during phase III. Lily responses to temperature during phase III differed from those during phases I and II (Wang and Roberts, 1983). Lily development rate, quantified as days to unfold a leaf, is a de- creasing linear function of average daily temperature between 14 and 30C during phases I and II (Karlsson et al., 1988). Lily development rate during phase III is a nonlinear function of temperature (Healy and Wilkins, 1984). The effect of temper- ature on the rate of lily development decreases as DT and/or NT increase during phase III (Rob and Wilkins, 1973; Healy and Wilkins, 1984). Easter lily morphological development is thermomorpho- genie. For instance, internode length increases as the DIF be- tween DT and NT increases (Erwin et al., 1989). In addition, leaf orientation, leaf length, and flower length are also influ- enced by diurnal changes in temperature.