摘要:

Germination and seedling emergence increased with increasing caryopses weight inScolochloa festucacea. Maximum seedling survival occurred when caryopses were planted 1 cm deep. Simulation of anaerobic conditions by soaking caryopses increased seedling emergence. Seedling emergence increased after imbibed caryopses were treated in a N2atmosphere. Emergence also was increased by soaking caryopses in 95% ethyl alcohol up to 60 min. Stratification apparently improved germination but was not a requirement.Scolochloa festucaceacaryopses were more tolerant of MgCl2than NaCl in the germination media. Optimum seedling growth occurred at 20C.

ISSN:0008-4026    

DOI:10.1139/b72-270

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Germination of conidia ofCurvularia geniculatafrom 20-, 40-, and 60-day-old cultures increased as temperature was increased to 15C. At 25C, maximum germination occurred among conidia from 20-day-old cultures, but germination from 40- and 60-day-old cultures decreased at and above 25C. Number and length of germ tubes and primary germ-tube branches increased on all conidia as temperature was increased from 5C to 25C and decreased above 25C. Germination also was influenced by culture age. Total and rate of germination decreased among conidia from older cultures at all temperatures; number and length of germ tubes and germ-tube branches also decreased on conidia from older cultures. Pathogenicity ofC. geniculatawas not clearly established.

ISSN:0008-4026    

DOI:10.1139/b72-271

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The development of microsclerotia ofVerticillium dahliaefrom a few swollen hyaline cells on a hypha to a multicellular, pigmented "mature" structure is described and illustrated. A method for quantitatively estimating the amount of pigmented microsclerotial material in pure cultures was developed to study quantitative relations between mycelial growth and production of microsclerotial material in media containing different concentrations of glucose. At low glucose concentrations (0.6 to 10 mg/ml) microsclerotial material continued to increase after total dry weight of the cultures had reached a maximum, suggesting conversion of hyaline to pigmented material. At high glucose concentrations (20 to 60 mg/ml) the patterns of increase in total dry weight, microsclerotial material, and hyaline material were similar over a 4-week incubation period. Maximum production of both pigmented and hyaline materials occurred at a glucose concentration of 30 mg/ml (carbon/nitrogen ratio of 50/1).

ISSN:0008-4026    

DOI:10.1139/b72-272

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Calcium, magnesium, potassium, sodium, and phosphorus concentrations were measured in the shoots of aPhragmites communiscommunity and its natural substrates during the growth season of 1969. Shoot length and shoot moisture were determined as indicators of physiological age. In addition, organic decay was followed by determination of the soil organic matter content and cation exchange capacity. Of the ions studied, calcium apparently increased in the shoot tissue, and magnesium, potassium, and phosphorus apparently decreased in the shoot tissue during the course of the growing season. Some speculations regarding the direction of net nutrient on flow in this community are advanced.

ISSN:0008-4026    

DOI:10.1139/b72-273

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In 1968–1970Pleurotus ostreatussporophores produced most spores in the afternoon during late fall and winter, when production increased with daily increases in temperature and decreases in relative humidity. In late summer and fall, production peaked between late afternoon and midnight. Diurnal production patterns did not occur in the laboratory at constant temperature, light, and relative humidity. At 85–95% relative humidity, sporulation increased exponentially with temperatures from 1 to 25C. Production ceased at less than 1C and above 27–30C. Alternating temperatures of 5 and 25C at 12-h intervals resulted in corresponding periods of high and low spore production which continued for up to 24 h after treatment ceased. At 17C, sporulation was higher at 30% relative humidity than at 90% relative humidity. Sporulation was unaffected by alternating light and darkness at constant temperature and relative humidity.

ISSN:0008-4026    

DOI:10.1139/b72-274

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In a comparative study of embryo development in intraspecific (U6 × K5/353) and interspecific (U6 × T33) crosses ofTheobroma, the development of the embryo sac as described by previous authors was confirmed. Disintegration of synergids showed that the growth of the pollen through the style was slightly quicker in intraspecific than in interspecific crosses, but the number of embryo sacs which had received male nuclei 3 days after pollination was about the same. Although gametic fusion and endosperm formation in the intraspecific cross was in advance of those in interspecific cross, the major blockage in species hybridization occurred subsequent to fertilization, and in most instances, well after the proembryo stage. Abnormal cell division and cell differentiation were contributory factors to poor seed formation. Possible causes of the abnormality have been discussed.Autonomous enlargement and the binucleate appearance of the egg cells in the unpollinated flower suggested a tendency to parthenogenesis and diploidization of the egg cell, under special conditions. Although a large proportion of thecacaoseeds observed in the species crosses are most probably intraspecific seedlings arising from contamination after controlled pollinations, the occurrence of a small number of true maternal seeds cannot be ruled out altogether.

ISSN:0008-4026    

DOI:10.1139/b72-275

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Experiments done with the modified soil perfusion apparatus indicate the potential capacity of the zoospores and cysts ofPhytophthora drechsleriandP. megaspermavar.sojaeas inoculum units in soil. The results indicate that although zoospores/cysts do not retain infectivity for months, those ofP. drechslerido not lose it very rapidly. Experiments done to find out the period of motility of zoospores have shown that somezoosporesofP. drechsleriandP. megaspermavar.sojaeremained motile for up to 30 and 24 h respectively. Saprophytic behavior of the two species ofPhytophthorahas been studied with the help of a fluorescence microscope and using a fluorescent dye. Cysts ofP. drechsleriandP. megaspermavar.sojaegerminate to a moderate degree in natural non-amended soil. Germination ranged from 30 to 50% in the case ofP. drechsleriand 15 to 25% inP. megaspermavar.sojae. Amending the soil with 0.4% glucose, 0.4% asparagine increased the percentage germination of cysts in natural soil. Germ tubes of a small percentage of cysts in the two species terminate in miniature sporangia-like structures.

ISSN:0008-4026    

DOI:10.1139/b72-276

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The taxonomy ofSaxifraga marshalliiandS. occidentalisis reviewed. On morphological, cytological, and distributional evidence, the new combinationS. marshalliissp.idahoensisis proposed for the taxon originally referred to asS. idahoensis. Keys to the taxa, synonomy, distributional records, maps, and chromosome numbers are presented.

ISSN:0008-4026    

DOI:10.1139/b72-277

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Seeds ofArceuthobium pusillumwere exposed to water, to various relative humidities, and to water followed weekly by various periods of dryness. With water, the seeds germinated more rapidly and produced longer radicles than with water in vapor form at any of the relative humidities used. At relative humidities between 90 and 100%, most of the seeds eventually germinated but the radicles remained short. Below 90% relative humidity, only a few seeds germinated. Some seeds germinated and produced radicles if exposed to weekly dry periods of up to 4 days.It is concluded that the distribution of the parasite is affected directly by water in liquid form, and indirectly by water in vapor form.

ISSN:0008-4026    

DOI:10.1139/b72-278

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Callus cultures were obtained for cyanide toxicity studies fromPrunus persicaL. (peach) and two grafting understocks,P. tomentosaThunb. (Nanking cherry) andP. besseyiBailey (sand cherry), which are used to dwarf peach.P. tomentosaandP. besseyicallus cultures were faster growing and more friable thanP. persicacallus. The callus derived fromP. persicawas more tolerant of high cyanide concentrations, whereas callus cultures from the two understocks were more sensitive to cyanide. The results suggest a detoxication system may exist in peach.

ISSN:0008-4026    

DOI:10.1139/b72-279

出版商:NRC Research Press    

年代:1972

数据来源: NRC