Hypocotyl Diameter Research Articles

Covariate Measurements for Increasing the Precision of Plant Response to O3 and SO2

Abstract Lettuce (Lactuca sativa L. cv. Grand Rapids) and radish (Raphanus sativus L. cv. Cherry Belle) plants growing at baseline environmental conditions were exposed to charcoal-filtered air, 0.40 ppm (v/v) ozone, and 0.80 ppm sulfur dioxide alone or in combination for 6 hours at 14 days from seeding. Analysis of covariance was used to account for significant within-treatment variation in plant growth. Covariates used were: planar leaf area (PLA) at 14 days for leaf area, fresh weight, and dry weight at harvest; plastochron index (PI) at 14 days for PI at harvest; and hypocotyl diameter for hypocotyl weights of radish roots at harvest. The covariates reduced the variability (standard geometric errors) of the response variables and increased the precision of statistical tests substantially for lettuce but much less for radish. For lettuce, the effect of the gas mixture on plant growth and foliar injury was less severe than that of the single gases. Radish plants, in contrast, exhibited no response to SO2 and the effects of O3 and the mixture on foliar injury and plant growth were similar.

低照度がハッカダイコンの初期の肥大生長に及ぼす影響

The effect of low light intensity on the growth and endogenous components (Cytokinin, auxin and sugar) of radish (Raphanus sativusL. radicula group) was investigated. In addition, Kinetin and naphthaleneacetic acid (NAA) was directly supplied to the intact hypocotyl to examine whether the inhibition of thickening growth of hypocotyl under a low light intensity could be overcome by them.Under a low light intensity, abnormal hypocotyl elongation was observed and the thickening of hypocotyl was markedly inhibited, so the T/R ratio became high. The cytokinin, auxin and sugar content of the hypocotyl rapidly increased with the thickneing growth under a high light intensity, but did not increase under a low light intensity.When intact hypocotyl was treated with kinetin or NAA under a low light intensity, NAA did not affect the thickening growth, but kinetin significantly increased the hypocotyl diameter. At the same time, hypocotyl elongation was inhibited by kinetin treatment.These results suggested that a decrease in cytokinin activity is one of the main factors inhibiting thickning growth of hypocotyl under a low light intensity and the inhibited growth can be overcome by a direct application of cytokinin to the intact hypocotyl.

Analytical Prediction of Seedling Emergence Force

ABSTRACT USING brittle plate theory, equations for the seedling emergence force as the seedling penetrates vertically through a crusted soil were developed for (a) grasses and cereals (point load), and (b) dicotyloedonous crops (dis-tributed load over a circle of diameter equal to hypocotyl diameter).

Soil Crusts and Cotton Emergence Relationships

ABSTRACT RAIN-FORMED soil crusts annually necessitate the replanting of thousands of hectares of cotton. Therefore, we studied the relationships of cotton emergence characteristics and soil-crust strength (penetrometer resistance), and the relative crust-breaking efficiencies of two mechanical devices. As penetrometer resistance increased, mean emergence date was delayed, emergence percentage was decreased, emergence rate index was reduced, and seedling hypocotyl diameter was increased. The rotary hoe was superior to the small-disk device only when the crust-breaking operation was delayed until some seedlings had already emerged.

Delayed Emergence and Temperature Influences on Cotton Seedling Vigor1

AbstractQuantitative information relating the effects of delayed emergence caused by soil crusting to cotton (Gossypium hirsutum L.) seedling vigor are needed to improve the technology for stand establishment. A greenhouse study measured the effect of crusted soil (Amarillo fine sandy loam, Aridic Paleustalfs) in delaying emergence for 50, 100, and 150% of normal emergence time for constant soil temperatures of 20, 25, and 30 C. Measurements of maximum emergence, seedling survival, hypocotyl diameter, and root disease rating were used as indicators of seedling vigor. Regression analysis indicated that seedling survival and hypocotyl diameter were minimal at 26 and 24 C, respectively, and root disease rating had a maximum value at 24 C. Seedling emergence and survival were significantly reduced when emergence was delayed between 50 and 100% of the normal emergence period, but almost all increase in hypocotyl diameter occurred in the first 50% delay. Estimates of reductions in vigor for seedlings emerging through crusted soil should be possible by measuring the degree of emergence delay and/ or hypocotyl diameter

Studies on the Seedling Emergence in Crops : Seed size and elongation force of soybean seedlings

Using an unbonded strain gauge transducer (1 kg) and an automatic balancing null recorder, the vertical elongation force (Ef) exerted by a seedling was measured at 24-26°C in darkness. The materials were thirty-four soybean cultivars (Glycine max (L.) Merr.) and six cultivars of six leguminous species including kidney bean (Phaseolus vulgaris L.), green gram (P. radiatus L. var. typicus Prain), lupin (Lupinus spp.), hyacinth bean (Dolichos lablab L.), asparagus bean (Vigna sequipedalis Wigth) and peanut (Arachis hypogaea L.). One seed was sown in a plastic pot 5 cm in diameter and 10 or 12 cm in depth. The seedbed was made from sandy loam soil which had been sieved through a 2.38-mm screen and which had about 13% moisture by volume. The soil was compacted to about 0.1 kg/cm3. The seeds were covered with 3 to 7 cm of loose, uncompacted soil. The seedlings were then grown in a dark chamber at 24-26°C. When the seedling had grown to 3, 5 or 7 cm in height, just emerging from the soil, the cotyledones of seedlings were attached to the force receptor of the transducer which was adjusted to 0 vertical force. Light effects on seedling growth were minimized byT handling them quickly under dim green light. Hypocotyl diameter was measured for calculation of stem area on seedlings which were grown under the same conditions as those used for the Ef tests. When the seedling had grown to 3 cm in height and was beginning to emerge, the loose surface soil was removed. The diameter at the center portion of the seedling, 1.5 cm above the stemroot junction, was measured to 0.1 mm using a caliper. Five to 16 seedlings of each entry were used for the Ef test, and three seedlings were used in the measurement of the diameter of hypocotyl. The results obtained were as follows. 1. The maximum Ef of 3 cm tall seedling in soybean varied according to seed mass of the same variety. In each material, the maximum Ef increased about 40g in small seed lot and about 10g in large seed lot with increasing 50mg of a seed weight. 2. In 3cm tall soybean seedlings, the mean value for the maximum Ef of a variety was positively correlated with seed mass (h=0.949). The maximum Ef per unit mass of seed was smaller in large-seeded soybean compared to small-seeded soybean. Furthermore, highly positive correlations were found between seed mass and strm area (r=0.952), and stem area and maximum Ef (r=0.934). The results indicate tha the large-seeded soybean produce large stems and therefore a large Ef. 3. In each of 3, 5 and 7cm tall seedlings, when seed mass is the same among soybean variety and another leguminous species which produed a hypocotyl, the mean value for the maximum Ef of a species was almost the same between soybean and green gram or lupin. However, the Ef was less in soybean than in kidney bean, hyacinth bean, asparagus bean and peanut.

Root Characteristics of Black Beans. II. Morphological Differences Among Genotypes1

Total root biomass of two black bean (Phaseolus vulgaris L.) cultivars, ‘Black Turtle Soup’ (BTS) and ‘Strain 39,’ and four black‐seeded lines (70001, 70002, 70003, and 70004) was partitioned into adventitious, basal, and taproot components at several growth stages under both greenhouse and field conditions. Basal root weights were significantly higher for the four lines in the field and for 70001 and 70002 in the greenhouse than for BTS and Strain 39. Genotypes did not differ for adventitious root weights in both environments. Taproot weights were higher for all the lines compared with BTS; and for 70001, 70003, and 70004 compared with Strain 39 in the field. Genotypes did not differ for taproot weights in the greenhouse.Stem, hypocotyl, and taproot diameters were significantly higher for all the lines than for the two cultivars in the field. Hypocotyl and stem diameters of all lines were higher than for the two cultivars, except for stem diameter of 70002 when compared with BTS in the greenhouse. Taproot diameters of 70001, 70002, and 70004 were significantly higher than for Strain 39 under greenhouse conditions. Basal root diameters (sum of individual basal root diameters) of the four lines were significantly higher than for BTS or Strain 39 in both experiments. Genotypes did^ot differ in the number of basal roots under field conditions.In the field, most root parameters increased up to the seed initiation stage, followed by a significant decrease or no further increase at the pod fill stage. Significant stage ✕ genotype interactions occurred for basal root diameter and hypocotyl diameter in the field and for taproot weight, stem, hypocotyl, and basal root diameters in the greenhouse. The erect plant type of the lines may be attributable to larger basal roots.

Associations Among Seed Weight, Seedling Emergence, and Planting Depth in Cicer Milkvetch1

AbstractThere is a great need for forage legumes that can emerge from deep depths of planting in semiarid environments because deep depths provide a greater cushion against the fluctuating moisture conditions found near the soil surface. Therefore, the objectives of this study were to compare selected progenies of cicer milkvetch, Astragalus cicer L., with seed weights of 3.2, 3.6, 4.0, 4.4, 4.8, 5.2, and 5.6 g/1,000 seeds for seedling traits that might be related to emergence and for ability to emerge from 1.3, 2.5, and 3.8‐cm depths of planting in the field.Seedlings from the seven seed classes differed significantly for hypocotyl diameter, hypocotyl length, radicle length, total length, and dry weight when grown in a dark germinator for 7 days at 25/15 C. In a greenhouse study the seed classes differed significantly for cotyledon dry weight, but not for cotyledon area, when sampled at the earlyprimary leaf stage. In both studies the values for the various characters generally were greater for the highseed‐weight classes than for the low.Although there were large differences between dates of planting both within and between years for seedling emergence in the field, the trends were similar with the high‐seed‐weight classes giving the greatest average emergence. The greatest difference among seed classes occurred at the 3.8‐cm depth, where seedling emergence of the 5.6‐g class was about twice that of the 3.2‐g class. Seedling emergence was similar for the 1.3 and 2.5‐cm depths of planting and generally was much higher for these two depths than for the 3.8‐cm depth. Correlation coefficients between seed weight, the various seedling traits, and seedling emergence at the 3.8‐cm depth were generally significant except for those involving hypocotyl length.

Selection indices using plant type characteristics in Navy beans (Phaseolus vulgaris L.)

SummaryA replicated trial of 18 families of Navy-bean breeding lines in the F4 generation was grown at Cambridge. The selection-index technique was used to investigate means of improving the efficiency of simultaneous selection for four criteria, namely yield, seed shape (numerical scores from ‘good’ to ‘poor’), early maturity and increased height of pod tips. Relative economic weights were chosen. The yield components and a range of characters describing plant type were measured making 15 characters in all, and combinations of these were included in 32 indices.It was predicted that simultaneous selection would be limited by adverse correlations between some of the four selection criteria, especially early maturity and height. The estimated efficiency of selection would hardly be improved by including information on the yield components. Combinations of the plant type characters, on the other hand, were predicted to provide considerable additional advance amounting to a 10% improvement when information on total number of nodes and inflorescences and hypocotyl diameter was included.It was concluded that the time involved in collecting yield component data would be better spent collecting information on a limited number of plant type characteristics in future trials, and that an ideal plant was one with reduced branching and a few heavily podded inflorescences borne on a tall plant with a strong base.

Hypocotyl Diameter as a Predictive Selectin Criterion in Sugarbeet1

Investigations concerning sugarbeet (Beta vulgaris L.) seedling characters and field root yield suggested a relationship between seedling hypocotyl diameter and root yield. This report deals with the hypocotyl diameter character and its relation to root yield, its genetic characteristics and its use as a selection criterion.The hypocotyl diameter of 3‐week‐old seedlings was measured with a micrometer caliper (graduations of 0.01 mm). Seedlings were grown in vermiculite in growth chambers and watered daily with equal amounts of nutrient solution. Hypocotyl diameter measurements were significantly correlated with root yield (0.70, 0.73, and 0.76) in three separate field trials. Significant heterosis for this character was observed in 14 of 18 crosses. In a six‐female ✕ three‐male sib analysis, general and specific combining ability and estimates of the proportion of additive to non‐additive genetic variance were similar for root yield and hypocotyl diameter. Selection of individual plants in heterozygous populations significantly increased the hypocotyl diameter of 3‐week‐old seedlings. The expected rate of increasing root yield (relative selection efficiency) when selecting for this character was 1.46 relative to selecting for root weight of space‐planted beets. These data suggest that this character could be an effective selection criterion for increasing root yield in sugarbeet.

Concentration Dependencies of Some Effects of Ethylene on Etiolated Pea, Peanut, Bean, and Cotton Seedlings

The effects of a series of concentrations of ethylene (10, 20, 40, to 10,240 nl/l) on elongation, diameter, and geotropism of the stems and roots of etiolated seedlings of Pisum sativum L., Arachis hypogea L., Phaseolus vulgaris L., and Gossypium hirsutum L. were measured or observed. Of the 24 possible responses, 4 were unaffected at the concentrations used, 5 were affected slightly, and the remaining responses exhibited a 14-fold range of apparent half-maximum concentration dependencies (i.e. 95 nl/l for the effect on pea epicotyl geotropism to 1350 nl/l for the promotion of cotton hypocotyl diameter). Six or possibly eight of these responses appear to have the same concentration dependencies while the others fell in pairs or as individual responses. The data, if interpreted in a manner analogous to enzyme kinetics, are indicative of more than one primary mechanism for ethylene action in plants.

Role of Ethylene in Induction of Flooding Damage in Sunflower

AbstractThe possibility that symptoms of flooding damage in plants are primarily caused by an accumulation of ethylene was investigated using pot‐grown sunflower (Helianthus annuus) plants.When plants were flooded to the basal pairs of leaves, ethylene in roots and stems below the water line began to increase. This coincided with the start of hypocotyl hypertrophy and new root formation in hypocotyls, which continued for 14‐16 days. There were highly significant correlations between ethylene concentration and number of roots and hypocotyl diameter.After approximately 4 days of flooding, ethylene concentrations in stems between nodes for the 1st and 3rd basal pairs of leaves started to increase, coinciding with initiation of chlorophyll breakdown and epinasty of the 2nd basal pairs of leaves. Thus, there were correlations between ethylene concentration and chlorophyll breakdown and epinasty. The lower the leaves, the more chlorophyll breakdown among 1st, 2nd, 3rd, and 4th basal pairs of leaves. The longer the flooding, the more severe the flooding damage; and even when returned to normal condition, plants flooded longer than 3 days were not able to recover from flooding damage.A gas chromatographic study revealed that Ethephon was absorbed by roots and decomposed to ethylene in the plant. Damage symptoms caused by soil application of Ethephon, such as reduced stem height, chlorophyll breakdown, epinasty of the 2nd basal pairs of leaves, and hypocotyl hypertrophy, were almost identical with those caused by soil flooding treatment.Microscopic studies revealed that radially enlarged cells and increased intercellular spaces in the cortex were the major contribution to the increased hypocotyl diameter in both flooded and Ethephon‐treated plants.It is concluded that the increase in ethylene concentration in flooded plants is largely, although not exclusively, responsible for flooding damage symptoms.

Effect of Picloram on Germination and Seedling Development of Four Species

Laboratory and greenhouse studies were conducted to determine the response of four plant species to 4-amino-3,5,6-trichloropicolinic acid (picloram). Germination of soybean (Glycine max(L.) Merr., var. Lee) seeds was inhibited, step-wise, by 10−8to 10−3M concentrations of picloram. Safflower (Carthamus tinctoriusL.) germination was inhibited at 10−3M; however, radish (Raphanus sativusL.) and barley (Hordeum vulgareL.) were not affected by any concentration studied (10−6to 10−3M). Measurement of several parameters of growth such as fresh and dry weight, shoot height, number and dimensions of leaves, percent necrosis, hypocotyl or epicotyl length, and hypocotyl diameter revealed that picloram was both growth promotive and inhibitory to safflower, radish, and barley. Levels of picloram required for growth promotion or inhibition varied with the species, stage of plant growth, herbicide concentration, the specific tissue, and the parameter being measured. Typical malformations such as twisting of stems, death of growing points, and occurrence of callus growth (depending on the species and herbicide dosage) were observed in picloram-treated seedlings. Studies on water loss by evapotranspiration suggested that picloram caused a possible alteration of stomatal behavior and/or a disturbance of water metabolism in plants under appropriate conditions.

Effects of Plant Population on Castorbean Yield1

AbstractPlant population effects on yield and growth of irrigated and non‐irrigated castorbeans (Ricinus communis L.) was tested for 3 years. The optimum plant population of irrigated dwarf‐internode castorbeans was about 58,000 plants per ha. Row spacings from 0.5 m to 1.0 m did not significantly affect yields, if plant population was held constant. The optimum plant population for nonirrigated castorbeans was near or higher than the highest population in our tests. It was clearly higher than the current recommendation of 20,000 plants per ha. Linear regression of yield on plant population was significantly different among cultivars and among tests for the nonirrigated castorbeans. Cultivars with bushy growth and small racemes had greater yield depression from low populations than did more erect cultivars with large racemes. Plant population effect on yield was reduced as the yield level of the nonirrigated tests decreased.Low plant population in nonirrigated tests increased plant height, hypocotyl diameter, length of primary raceme, number of racemes per sequential set, and yield of all sets of racemes. Low population reduced height of the primary raceme from the soil. Population had no effect on nodes to the primary raceme. Oil content of the seed or test weight were not affected by plant population of nonirrigated castorbeans.

Influence of Planting Date on Certain Morphological Characteristics of Castorbeans1

AbstractCastorbean (Ricinus communis L.) plants were taken from irrigated and nonirrigated date‐of‐planting tests for 3 years to determine the effect of planting date on plant morphology. Planting date had no effect on plant height, except where drought was a factor. Hypocotyl diameter at harvest was significantly smaller with later planting dates. The number of nodes below the primary raceme, the distance from soil surface to primary raceme, length of primary raceme, and yield of primary raceme were significantly higher on June 13 planting date for three of the four varieties for all years. Morphology of the fourth variety, ‘Cimarron Hybrid’, was not affected greatly by planting date. Morphology of secondary and subsequent racemes was not affected greatly by planting date.

Castorbean Production as Related to Length of Growing Season. II. Date of Planting Tests1

AbstractYield of irrigated castorbeans (Ricinus communis L.) in Nebraska was highest when planted the first 2 weeks of May, particularly when Alternaria leaf spot [Alternaria ricini (Yoshii) Hansford] was not a factor in the results. for nonirrigated castorbeans there was little difference in yield for any May plantings. April and June plantings were lower in yield. The time required for emergence was correlated with soil temperature and decreased with later plantings. Total emergence increased from 55% for March planting to 75% for June plantings. Lodging was inversely correlated with hypocotyl diameter within but not between varieties. Weight per 100 seeds in most cases was highest for primary racemes and progressively lower for secondary, tertiary, and quaternary racemes. Seed from racemes, particularly tertiary and quaternary, rapidly decreased in weight with later plantings. A positive and significant correlation coefficient of 0.88 was found between weight per 100 seeds and germination percentage. Seeds from earlier planting dates tend to have higher germination.