Growth Room Experiments Research Articles

Plant Yield and Nitrogen Content of a Digitgrass in Response to Azospirillum Inoculation

Two Australian soils, a vertisol (pH 6.8, 0.299% N) and a sandy yellow podzol (pH 6.2, 0.042% N), were used with digitgrass, Digitaria sp. X46-2 (PI 421785), in a growth room experiment. Comparisons were made between plants inoculated with live and autoclaved bacterial suspensions of Australian and Brazilian isolates of Azospirillum brasilense. Seedlings were inoculated on days 10 and 35. Acetylene-reducing activity was measured five times during the experiment. Dry matter yields of the digitgrass on the podzol (low N) inoculated with live bacteria were 23% higher than those of the controls. On the vertisol (high N), yield increases from inoculation with live bacteria were 8.5%. The higher-yielding plants had significantly lower percent nitrogen, but when total nitrogen of the tops was calculated, the inoculated plants had a higher total N than did the controls (P=0.04). Acetylene-reducing activity was variable in the experiment, ranging from 0.5 to 11.9 mumol of C(2)H(4) core day. Live bacterial treatment induced a proliferation of roots, possible earlier maturity, higher percent dry matter, and a higher total N in the tops.

The Effects of Position and Temperature on the Expansion of Leaves of Vicia faba L.

The growth in area of the first eight leaves of broad bean plants was investigated in growth room experiments. Plants were grown at either 20 or 14 °C or transferred from 20 to 14 °C. Rates of leaf appearance and unfolding increased with temperature. The duration of growth of a leaf increased with leaf number for the first five leaves and then remained constant. The mean growth rate declined or remained constant with increasing leaf number. Durations of growth were shorter and growth rates larger at 20 °C than at 14 °C. Plants responded immediately to the change in temperature. Final areas of leaves which expanded after transfer from 20 to 14 °C were larger than those grown at 20 °C.

COMPARISON OF THE EFFECT OF NO3- AND NH4-N ONGROWTH, YIELD, AND YIELD COMPONENTS OF MANITOU SPRING WHEAT AND CONQUEST BARLEY

The objective of this study was to compare the effects of NO3 and NH4 forms of nitrogen on the growth and yield of spring wheat and barley. Two growth-room experiments were carried out using spring wheat (Triticum aestivum L. ’Manitou’) in both experiments and barley (Hordeum vulgare L. ’Conquest’) in the second. NO3 or NH4-N plus the nitrification inhibitor nitrapyrin were applied at rates from 23 to 360 kg N/ha. Temperatures were 27/12 °C (day/night) and soil moisture was maintained at between −0.05 and −1.0 bars by frequent watering. NO3-N-treated plants were taller, and had thicker stems and more spikelets/spike than NH4-N-treated plants. The NH4-N-treated plants produced more spikes and matured faster initially, although by anthesis stage there was little difference in maturity between the NO3- and NH4-N-treated plants. There was no differential effect of nitrogen source on total dry matter at maturity, although dry matter increased in proportion to nitrogen rate. Grain yield of the NH4-N-fed plants was higher than that of the NO3-N-fed plants, especially at the higher nitrogen rates. This was due primarily to the effect on number of spikes produced and secondarily on seed set. It is suspected that denitrification losses of nitrogen from the NO3-N-treated soil contributed to the differential response to the two sources, but there was circumstantial evidence to suggest that some of the difference may have been due to the inherent nature of the two sources which might have affected their ease of metabolism by the plant.

Effect of Stage of Growth, Temperature, and N and P Levels on the Hydrocyanic Acid Potential of Sorghums in the Field and Growth Room1

Variation in hydrocyanic acid potential (HCN‐p) was studied in three sudangrass [Sorghum sudanense (Piper) Stapf] strains and S. almum Parodi. Under field conditions, nitrogen application did not result in a significant change in HCN‐p, but strain and stage of growth when sampled had highly significant effects. ‘Sweet’ sudangrass and S. almum were high in HCN‐p, while ‘Piper’ and Line 109 (L109) sudangrasses were low in HCN‐p. Forty‐five days after planting HCN.p peaked, then dropped sharply during the following 15‐day interval.In the first experiment performed under controlled environmental conditions, HCN‐p differences among the four strains were highly significant. When P concentration in Hoagland’s solution was increased from 0.0 ppm to 31.0 ppm, HCN‐p was reduced significantly. Lowering the temperature from 30 C day/20 C night to 20/10 C resulted in a highly significant increase in HCN‐p. In the second growth room experiment, a low HCN‐p strain, L109, was significantly lower in HCN‐p than the cultivar, Piper, under three N levels. HCN‐p was associated with N‐level, being lowest at the low N rate. Under both 30/20 C and 20/10 C temperature regimes, HCN‐p was higher when the plants were 30 days old, than when they were 45 days old. Also, HCN‐p was lower at 30/20 C than at 20/10 C. When both temperature regimes were lowered to 10/10 C for 10 days, the HCN‐p in 55‐day old plants was greater than in the 45‐day old plants. On the other hand, further reduction of temperature to −5/−5 C for one day at day 55, resulted in the lowest HCN‐p 56 days after planting.

Relationships between Fusarium nivale and other micro-organisms on seed of wheat and barley

Relationships among common saprophytes of the field microflora of wheat and barley seed and the pathogens Fusarium nivale (Fr.) Ces. and Septoria nodorum Berk. were studied. Relationships at the seed germination stage were examined in growth room experiments by observing the effects of inoculating seed with mixtures of organisms on development of seedling disease. Alternaria was the saprophytic fungus most antagonistic to F. nivale, but different isolates of Alternaria and Epicoccum affected both pathogens differently. Relationships during colonization of seed on the ripening ear were studied in glasshouse experiments. F. nivale was generally inhibited by Alternaria.

Abscisic Acid and the Photoperiodic Induction of Dormancy in Salix viminalis L

A series of growth room experiments was carried out aiming to establish the role of abscisic acid on dormancy of Salix viminalis L. The inhibitor content and abscisic acid levels of extracts from roots, sap, leaves, and apical tissues of willow were measured using biological assay and gas-liquid chromatography.No evidence was obtained that photoperiodically mediated dormancy is associated with changes in abscisic acid levels or beta-inhibitor activity.

Effects of organomercury treatment of wheat seed on Fusarium seedling disease in inoculated soil

SUMMARYIn growth room experiments, treatment of wheat seed with phenyl mercuric acetate significantly reduced seedling disease caused by soil‐borne Fusarium culmorum, F. nivale and F. avenaceum in inoculated soil. Seed treatment improved the low germination caused by F. culmorum, but did not affect the reduced seedling vigour caused by F. nivale. Seed treatment was normally as effective in conditions favouring disease as it was in less favourable conditions. Conditions favouring disease in soil inoculated with F. culmorum were high inoculum level, deep sowing and dry soil.

Seedling vigour and grain yield of cereals grown from seeds of varying protein contents

SUMMARYThe effect of seed protein content on grain yield has been studied in varieties of spring barley, oats and wheat grown under differing cultural conditions. Grain yield was affected by seed protein content in one experiment where very low yields were attained, but the effects were inconsistent. No effect was observed in two other experiments made in a glasshouse and the field. In a growth-room experiment, seed with high protein content produced more vigorous seedlings than low-protein seed; these differences were accentuated by increasing seedling age at very low nutrient levels, but decreased with seedling age at normal nutrient levels. It is concluded from the results that variations in seed protein content are unlikely to have a significant effect on yield under practical conditions.

Development of a seedling screening test for predicting relative grain protein content in oats

Growth room experiments were conducted to study associations of grain protein content with properties of seedling leaf sections of oats (Avena sativa L.) using (1) 10 cultivars differing genetically in grain % protein, and (2) 10 populations of a single high protien cultivar (Hinoat) differing phenotypically in grain % protein. These populations, which were derived from a nitrogen fertilizer experiment, had grain protein concentrations which varied over the whole range displayed by the high and low protein cultivars when the latter were tested in a conventional field trial.

Effects of chloromequat chloride on related tall and dwarf rice varieties

SUMMARYThe effects in growth room experiments of three levels of 2‐chloroethyltrimethylammonium chloride (chloromequat chloride; CCC) at two nitrogen levels were studied on a tall rice variety and a mutant dwarf derivative. CCC was found to reduce plant height in both varieties, to increase tiller number and spikelet number on the main panicle or in total but to delay flowering. Chemical dwarfing cannot be regarded as an alternative to genetic dwarfing since mutants may be shorter than chemically treated tall genotypes and may themselves respond favourably to further treatment.

EFFECTS OF NITROGEN AND MOISTURE ON YIELD AND PROTEIN IN FIELD PEAS

When averaged over a wide range in soil nitrogen and moisture conditions, cultivar differences in yield and protein content of non-inoculated field peas (Pisum sativum L.) were relatively small. The inherent differences in seed weight were responsible for most of the variations in yield among the three cultivars. Nitrogen fertilization in the growth room experiment markedly increased plant weight, seed yield and protein content, and water-use efficiency was substantially improved. When maintained within the upper half of the available range, soil moisture supply had only a limited influence on plant growth. Periodic wilting did cause a severe reduction in plant weight and seed yield, but there was little change in protein content. For these fertilizer and moisture treatments, responses in seed yield were primarily due to changes in number of pods per plant; the seeds per pod and seed weight were relatively stable. It appeared that field peas were efficient converters of soil nitrogen to seed protein and, in the absence of nitrogen-fixing bacteria, nitrogen fertilization was the principal factor influencing the protein content of field peas. The correlation coefficient between yield and protein content was very low.

Effect of temperature on the expression of the naked grain character in oats

The effect of temperature on the expression of the naked grain character in oats was studied in a growth room experiment which compared eight naked oat genotypes grown at temperatures of 15, 20 and 25°C. Expression of grain nakedness and temperature level were positively associated and a genotype x temperature interaction was shown.

Corn Emergence in Relation to Soil Temperature and Seeding Depth1

AbstractField and growth room experiments at Mandan, N. D., evaluated the effects of seed depth and soil temperature on corn (Zea mays L.) germination and emergence. In the growth room, from 4 to 24 days were required to achieve 80% emergence, depending upon soil temperature and seed depth. Increasing soil temperature from 13.3 to 26.7 C reduced the time for 80% emergence. Temperature had a much greater effect than seed depth on emergence. A highly significant linear relationship existed between percent emergence and cumulative degree‐days above 10 C.In field treatments with adequate soil water for germination, 8 to 13 days were required for near 80% germination. About one additional day was required for each 2.5‐cm increase in depth of planting. For corn placed at 7.6 cm, about 10 days and 68 cumulative degree‐days were required for emergence. Similar degree‐day requirements occurred for the 12.7‐cm depth. Degree‐day requirements for field experiments agreed very well with those obtained in the growth room.

MOVEMENT OF PHOSPHORUS TO BARLEY ROOTS GROWING IN SOIL

A plant growth room experiment was conducted using seven soils of Alberta with a treatment of 300 ppm of P on four of the soils. The contributions to the movement of P to the roots were calculated according to the method of Barber and co-workers, with some modifications. Results of the experiment showed clearly that movement by mass flow was the most important process of P transport to roots in soils treated with 300 ppm of P. Apparent diffusion was found to be the major process of P movement to roots in untreated soils, which included two soils with naturally high levels of available P. Root interception was found to be of least importance in P movement to roots. Since the concentration of P in soil solution affected the amounts of P reaching the roots by diffusion, mass flow or root interception, the importance of the determination of soil solution P is emphasized. A correlation of 0.86 was obtained between the yield and soil solution P concentration of the untreated soils.

Effects of Temperature and Light Intensity on the Growth of Scrophularia Marilandica

The effects of temperature and light intensity on the growth of Scrophularia marilandica L. were studies under artificial, semi—natural, and natural environmental conditions. The plants in the controlled environment rooms were grown under 10 different combinations of temperature (48°/58°—63°/73°F) and light intensity (24—123 cal/cm2/day). The plants in the semi—natural experiment were grown outdoors on prepared plots representing seven levels of average radiation ranging from 20.4 to 405.7 cal/cm2/day. Net assimilation rate (NAR) was proportional to light intensity up to 123 cal/cm2/day in the growth rooms. In the semi—natural studies, it was proportional up to 150 cal/cm2/day and from this point up to 300 cal/cm2/day, NAR increased but not proportionally. Above 300 cal/cm2/day NAR was independent of solar radiation. Under controlled conditions NAR decreased slightly with age at the highest light levels. The length of the vegetative phase, the specific leaf area, and the leaf—area ratio were sharply decreased at higher light intensities. The dry weight of all plant organs was augmented by high light intensities. Roots and axillary shoots were especially sensitive. In the growth—room experiments, temperature effects were more pronounced than were light effects. Stem elongation was completely inhibited at temperature regimes below 63°/73°F, and leaf expansion was markedly diminished below 57°/68°F. Consequently the shoot developed a rosette habit and flowering was inhibited. Decreases in temperature to 48°/58°F had little effect of root growth. The net effect of low temperatures was to depress the shoot—root ratio. However, NAR was increased by a reduction in temperature from 63°/73° to 48°/58° at all intensities. The shoot—root ratio of shaded plants was increased to a greater extent by a rise in temperature than was that of the unshaded plants. Regardless of light level, plants at 48°/58°F consistently had a smaller shoot—root ratio than did those at 63°/73°F. Inhibition of stem elongation and subsequent rosette development at low temperatures were not affected by changes in light intensity. The usual development of greater leaf areas by plants growing under lower light intensities was partially reversed at low temperatures. In early spring shoots of native Scrophularia marilandica sprouted from crown buds attached to perennial roots. The timing differential between leaf expansion in April and shoot elongation in May appears to be a temperature—photoperiod interaction. In early spring and autumn cool temperatures which repressed shoot growth had little effect on root growth. Roots increased greatly in size through late summer into early autumn.

Saline soils under dryland agriculture in southeastern Saskatchewan (Canada) and possibilities for their improvement

Yields of wheat, when grown on saline soil under dryland conditions were increased by treatments such as mulch, manure, high rates of nitrogen and phosphorus fertilizers in combination or alone and by Krilium. On the other hand, all treatments, with the exception of Krilium, had no effect on the salinity concentrations of the 0–6 inch soil layer. It was concluded that all three factors, namely fertility improvement, structure improvement, and moisture perservation contributed towards higher yields on saline soil. The return, however, as evidenced from field and growth room experiments, was decreasing with increasing salinity. This reduction in responsiveness, which is significant for practical agriculture, was ascribed mainly to a reduction in the availability of nutrients to plants when grown on saline soils.

Observations on the influence of plant illumination on the fungal flora of roots.

Greenhouse and plant growth room experiments showed that shading of plants had no appreciable effect on the vegetatively active fungi colonizing the primary roots of wheat and soybean seedlings growing in fertile, disease-free soil. Although marked differences in plant development were obvious, the general pattern of root colonization was essentially the same for the two levels of illumination used. The results suggest that the saprophytic fungi which normally colonize the roots of healthy plants may also colonize roots of abnormal plants providing that the soil is relatively free from plant pathogenic forms.Species of Phoma accounted for a much higher proportion of the isolates from wheat roots than from soybean roots, whereas the majority of cultures from soybeans proved to be species of Fusarium.