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1.
Physical conditions of propagation media and their influence on the rooting of cuttings 总被引:1,自引:0,他引:1
Hans R. Gislerød 《Plant and Soil》1983,75(1):1-14
Summary The formation and subsequent growth of roots by cuttings of poinsettia, hydrangea, rose and azalea in various propagation media, Jiffy-7, Jiffy-9 and Grodan under different conditions of aeration was investigated. The interrelationships of the effects of air content of the media, temperature and light intensity on the rooting of poinsettia cuttings was also studied.With low air contents (0 cm moisture tension) in the propagation media the formation and growth of roots was strongly inhibited. The rooting performance of rose appeared to be less affected by the poor aeration. Increasing air content improved rooting but best results were obtained at moisture tensions of 4 to 8 cm. Rooting seems to be better correlated with oxygen diffusion rate (ODR) than with air content.For poinsettia cuttings the optimum temperature for rooting was 24 to 28°C. At low temperatures rooting was delayed while at higher temperatures it was almost completely inhibited. Callus formation increased with temperature but decreased with increasing moisture tension. Conditions which induced large callus formation inhibited root formation.High light intensity during rooting reduced overall rooting performance and the inhibition was most pronounced in conjunction with high moisture tensions.Report No. 255. 相似文献
2.
3.
Summary The concentration, uptake and element use efficiency of N, P and K in one C3 annual (Polypogon monspeliensis) and two C4 (Echinochloa colonum, an annual, andDichathium annulatum, a perennial) grasses were determined during winter and summer seasons in monocultures raised in field plots at three moisture
levels,viz. full, half and one-fourth of field capacity. At each moisture regime the plants were clipped thrice at moderate and severe
levels corresponding to 40 and 80% of live green. The concentration of these elements was characteristic of the growth habit
of these plants;e.g. the build up of concentration was maximum in leaf of the annuals while it was comparable in crown and leaf of Dichanthium.
The N level was maximum in Polypogon. The nutrient use effiency was comparable in the two annuals and maximum K and N use
were obtained in Polypogon and Dichanthium, respectively. 相似文献
4.
Hans R. Gislerød 《Plant and Soil》1982,69(3):445-456
Summary The air content in three types of propagation media, Jiffy-7 and Jiffy-9 which are Sphagnum peat and Grodan which is rockwool,
were investigated when they were held at moisture tensions of 0,6 and 12 cm measured from the base of the media. At 0 cm tension
the air content (vol. %) was highest in Jiffy-9 and lowest in Jiffy-7. At 12 cm tension the air content was higher in Grodan
than in Jiffy-9 and Jiffy-7.
Oxygen diffusion coefficients (ODC) and oxygen diffusion rates (ODR) were measured at the different air contents. At air contents
below 20 vol. % ODC was about the same for Jiffy-9 and Grodan but at air contents above 20 vol.% it was larger for Jiffy-9
than for Grodan. The oxygen diffusion rate was measured at 0, 4 and 8 cm moisture tension. At all tensions it was approximately
20% higher in Jiffy-9 than in Grodan and Jiffy-7. The ODR in Jiffy-7 and Grodan were affected equally at the same tension,
although Grodan contained more air.
Report no 253 相似文献
5.
P. SOMAN 《The Annals of applied biology》1990,116(2):357-364
The ability of crops of sorghum (Sorghum bicolor (L.) Moench) to establish in farmers' fields depends largely on its capacity to germinate and emerge under limited soil moisture conditions. Studies on germination under moisture stress have been previously conducted using osmotic media which do not wholly reproduce the conditions of the seed bed in the field. Hence the need for a field screening technique. A line source irrigation system was used to provide five moisture regimes ranging from -0.08 MPa to -0.92 MPa. The drying rate of the soil and the soil temperature depended largely on incident radiation, and the relationship between the moisture content and daily soil temperature and daily radiation was consistant. Total porosity of the seed bed, derived from bulk density measurements and particle density ranged from 43.8% to 45.3%, which would allow sufficient aeration when as in the experiments conducted here, water content was low (> 0.14 g/g). Under these seed bed conditions the pattern of response of emergence to the moisture gradient was linear or curvilinear. Genotypic differences existed for emergence and its response to water level. The field method developed is useful for identifying genotypes able to germinate and emerge under conditions of low seed bed moisture. 相似文献
6.
Summary The effect of soil moisture stress on growth, nodulation and nitrogenase activity of two tropical forage legumes,Macroptilium atropurpureum cv. Siratro andDesmodium intortum cv. Greenleaf was studied in a pot experiment. After ten weeks growth, the highest moisture stress (20 per cent water holding capacity) significantly reduced only the top weight of both plants. Moisture stress progressively retarded top growth in the two legumes. Similar trends were also observed in defoliated plants. Moisture stress had little or no effect on the nodulation or nitrogenase activity of the plants. 相似文献
7.
Principal component analysis (PCA) was used to determine the effects of infestation of bulk stored wheat by multiple species of insects at 30±2°C for 60 wk. Eight 204-liter drums containing wheat at 15.5% moisture content were used as three distinct man-made ecosystems: (a) Control system (2 drums), insect-free; (b) RST system (3 drums), artificially infested with Rhyzopertha dominica (F.),Sitophilus oryzae (L.), and Tribolium castaneum (Herbst ); and (c) COT system (3 drums), infested with Cryptolestes ferrugineus (Stephens ),Oryzaephilus surinamensis (L.), and Tribolium castaneum. The variables measured tri-weekly within each system included carbon dioxide, oxygen, temperature, grain moisture, seed damage, grain weight and volume, dust weight and volume, fat acidity values (FAV) of the wheat, seed germination, microflora including Alternaria alternata(Fr.) Keissler ,Aspergillus glaucus group, Aspergillus candidusLink , and bacteria, insects and the mite Tarsonemus granariusLindquist . PCA provided multivariate synopsis of the data quantifying several important relationships among the variables monitored. Tri-weekly and cumulative 60-wk analyses of each system showed that high bacterial counts were associated with high FAV levels;Tarsonemus numbers were positively related to Aspergillus; Alternaria and seed germination were negatively related to FAV, bacteria and grain damage; and that the number of insects was related to the presence of Aspergillus and negatively related to the presence of bacteria. Seed germination and Alternaria infection often decrease rapidly presumably because of infection by fungi of the Aspergillus glaucus group. The combined action of R. dominica and Aspergillus spp. enhanced seed damage and increased grain moisture content thus promoting bacterial growth which in turn inhibited insect and mold growth. Fat acidity values increased with time unless seed damage and bacterial infection were extensive as in the RST system. 相似文献
8.
Carboxymethyl chitosans (CM-chitosan) of various degrees of deacetylation (DD 28-95%) and substitution (DS 0.15-1.21) were successfully prepared from N-acetylchitosans in NaOH of varying concentrations. Infrared spectroscopy (IR), elemental analysis, potentiometric titration, 13C NMR, X-ray diffraction and gel-permeation chromatographic (GPC) techniques were used to characterize their molecular structures. The moisture-absorption (R(a)) and -retention (R(h)) abilities of CM-chitosan are closely related to the DD and DS values. Under conditions of high relative humidity, the maximum R(a) and R(h) were obtained at DD values of about 50%, and when the DD value deviated from 50%, R(a) and R(h) decreased. Under dry conditions, when the DD value was 50%, the R(h) was the lowest. With the DS value increasing, R(a) and R(h) increased. However, further increase of the DS value above 1.0 reduced the increasing tendency of R(a) and R(h), and even some decreases in R(a) and R(h) were observed. Intermolecular hydrogen bonds play a very important role in moisture-absorption and retention ability of CM-chitosan. 相似文献
9.
This experiment tested the hypothesis that using near-infrared (IR) imaging spectrometry on tablets through blister packs
permits the identification and composition of multiple individual tablets to be determined simultaneously. Aspirin was selected
for this study because its breakdown mechanism is well understood. Near-IR cameras were used to collect thousands of spectra
simultaneously from a field of packaged aspirin tablets. Tablets were selected by a principal component analysis selection
alogorithm. Graphs of the columns of the transformation matrix showed that salicylic acid and acetylsalicylic acid in the
samples were modeled by the principal components. The bootstrap error-adjusted single-sample technique chemometric-imaging
algorithm was used to draw probability-density contour plots that revealed tablet composition. Choice of color was used to
represent constituent identity, whereas intensity represented concentration. The percentage of usable pixels in the indium
antimonide (InSb) array was 99.9%. The SEP was 0.06% of the tablet mass for both water uptake and salicylic acid production.
The number of tablets that a typical near-IR camera can currently analyze simultaneously was also estimated to be approximately
1300. 相似文献
10.
光照、湿度和培养基对苎麻疫霉卵孢子产生量的影响 总被引:1,自引:0,他引:1
采用3因素随机区组设计研究了光照、湿度和培养基对苎麻疫霉(hytophthoraboehmeriae)卵孢子产生量的影响。结果表明,各因子对卵孢子产生量的影响效应大小次序为培养基>光照>湿度,其中培养基和光照两因子影响均在0.01水平上显着。在供试的4种常用培养基上,卵孢子产生量的大小次序为:SLA培养基(SLA)>利马豆培养基(LBA)>V6汁培养基(V6A)>澄清的V6汁培养基(V6B).在设置的3种光照条件中,卵孢子产生量以连续黑暗处理最高,连续光照最低,光照与黑暗交替处理居中。3个试验因子间的所有互作对卵孢子产生量均有极显着的影响。在不同光照、湿度、培养基组合中,卵孢子产生量以低湿+连续黑暗+SLA组合最高,低湿+连续光照+V6B组合最低。 相似文献