Onion Seedlings Research Articles

Isoenzyme Polymorphism in Flowering Plants

AbstractA total of 21 esterase, 3 acid phosphatase and 2 leucinc aminopeptidase isoenzymes, in addition to peroxidases and catalases, were demonstrated in onion seedlings by starch‐gel electrophoresis. In seedlings two weeks old, the root tip and the differentiated zone show very little enzymatic activity, whereas the secondary roots, hypo‐cotyl and cotyledon are enzymatically very active. These differences are correlated with the intensity of cell division. Some esterase isoenzymes are apparently restricted to root, others to shoot tissues. At pH 8.1, anodically moving peroxidases are totally absent from shoot tissues.A developmental study of esterase isoenzyme patterns indicated that no great differences exist between primary root tips from roots 6–18 mm long and seeds germinated for three days, whereas a sudden decrease in enzymatic activity occurs in root tips after seven days' germination when the roots are about 25 mm long. This coincides with the decrease in mitotic Frequency.Actinomycin D and gamma irradiation decreased mitotic frequency almost to zero but did not significantly affect the esterase isoenzyme pattern in root tips. This shows that the activity of these isoenzymes, at least, is not necessarily dependent on cell division but may well be a prerequisite for it.

Efeito do herbicida ramrod em canteiros de semeação de cebola

Experimentos foram conduzidos, em solo areno-argiloso da formação Glacial, em Campinas, para estudar os efeitos da aplicação do herbicida «Ramrod» em canteiros para formação de mudas de cebola. Foram testadas as doses de 1,30, 1,95, 2,60, 3,90 e 5,20 kg/ha de ingrediente ativo. Em relação ao combate às ervas más dicotiledôneas, apenas a dose de 1,30 kg/ha não foi superior à da testemunha. Para qualquer das doses utilizadas não se verificaram sintomas visuais de fitotoxicidade nas plantas. Pequeno efeito residual do produto foi constatado em todas as doses, aos 50-60 dias após a aplicação.

Pleospora herbarum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Pleospora herbarum . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On a wide range of hosts including apple, ash, broad bean, clover, endive, gladiolus, gramineae, lettuce, lupin, muskmelon, onion, Onobrychis, Medicago sativa , mangold, tomato, Trifolium, Vicia (40: 230). DISEASES: Leaf spot of mangold, clover ( Trifolium ), lucerne ( Medicago sativa ), endive, lettuce, onion seedlings and gladiolus, net blotch of field and broad bean ( Vicia ), ring spot of sanfoin ( Onobrychis ) foot rot of tomato. Severe leaf spot on muskmelon may cause leaf fall and sun scald of fruit (37: 625). Lesions caused by other fungi may also be colonized as on lucerne (38: 11) or be associated with some other disease complex such as Pseudomonas savastanoi on ash (36: 144). GEOGRAPHICAL DISTRIBUTION: World-wide; very common in temperate and sub-tropical regions. TRANSMISSION: Generally air-borne as ascospores or conidia. These penetrate the leaf or petiole via stomata (37: 365). May also occur on seeds (38: 146) and in soil.

Physiological studies on the bulbing and dormancy of onion plant. XI

This paper reports the physical factor in onion juice.1. It was clearly shown that ether-insoluble fraction in onion juice remarkably depressed the seed germination.2. It was also shown that the same concentration of NaCl or KNO3 solutions as that of onion juice inhibited both germination of seeds and growth of onion seedlings, and that the addition of ether extracts obtained from onion juice to Nacl solution enhanced the inhibition of seed germination more than NaCl solution only.3. Refractometer index of onion juice increased with bulb thickening and reached a maximum value a month later followed by a gradual decline.The inhibition of seed germination by onion juice was significantly correlated with the refractometer index of it.4. Ohshu, a late variety, showed higher value in refractometer index of juice and more strong inhibition of seed germination than Senshu-Ki, a middle one.5. The effect of concentration of reducing sugar and sucrose as substrate on the respiration metabolism of terminal part of stem disk or crude enzyme with Warburg manometer suggested that the same concentration of substrate as that of onion juice depressed considerably the respiration.6. On the basis of foregoing results it was concluded that sugar accumulation accompanied with bulbing induces the depression of respiration metabolism, resulted in rest in bulb, and that the gradual decline in sugar concentration by respiration in bulb during storage allows the terminal bud to renew the growth.

Alteration in the Geotropic Response of Allium Seedlings by Growth Regulators

AbstractIndoleacetic acid (1AA) brings about a striking alteration in the normal geotropic response in the seedlings of onion and several other species of Allium. The seedlings which are normally positively geotropic, become ageotropic. Besides IAA several other auxins like IBA, NAA and 2,4‐D also showed a similar response. An anti‐auxin like triiodobenzoic acid (TIBA) enhanced the auxin‐effect instead of reversing it. A marked enhancement of the auxin‐effect was also brought about when sucrose (in the culture medium) was replaced by L‐arabinose which appeared to act synergistically with the auxin.

Physiological studies on the bulbing and dormancy of onion plant. IX.

The relationship between dormancy of bulb and the properties of its juice was pursued by using the general methods available for study on the seed dormancy.1. The color reaction to tetrazolium was observed only on the terminal part of stem disk in rest bulbs and on the all part of section in sprouted ones. This result suggests that the terminal bud is active and the other part of bulbs inactive during rest. Consequently it appears that rest is a suspension of growth of terminal bud caused by either the shortage of substances available for growth or excess of growth inhibiting substances translocated from thickened leaf sheaths.2. Fresh juice from rest bulbs remarkably inhibited both germination of various seeds and growth of onion seedlings. This inhibiting action of onion juice was not so severe with water-imbibed seeds as with dry seeds. And further it was removed by washing them with running water, but their germination percentage was still low as compared with that of water-incubated seeds.The inhibiting action and pH of onion juice did not change by heat treatment.These results showed clearly that the inhibiting action of onion juice is due to both chemical and physical properties of it.3. It was shown that the inhibiting action of onion juice gradually decreased with increase in number of days after harvest during storage at room temperature, that is, the seed germination was remarkably inhibited with each juice prepared from various part of rest bulbs, but was slightly inhibited only with juice from inner part of sprouted ones.This tendency was promoted by unfavorable storage conditions, i.e. wet moisture and oxygen supply.4. Onion juice prepared from Ohshu, a late variety, showed stronger inhibiting action than that of Senshu-ki, a meduim variety.5. It may be safely concluded from these results that the lowering of inhibiting action of onion juice significantly correlates with earliness of sprouting in bulbs.

Soil potassium and the growth of vegetable seedlings. II.—Effect of potassium and ammonium salts on the growth and composition of seedlings

AbstractThe effects of applications of potassium nitrate, potassium sulphate with ammonium nitrate, and farmyard manure (FYM) with ammonium nitrate on the growth and mineral composition of seedlings of lettuce, cabbage, onion and carrot were measured. The main purpose of the experiment was to find whether the sulphate in potassium sulphate supplying 400 lb. of K per acre damaged seedling growth; the results show that it did not.The FYM applications increased the cation‐exchange capacity of the soil (by 27%) and the amount of exchangeable potassium in the soil but had little effect on the exchangeable calcium and magnesium contents. The effects of these changes and of the added fertilisers on the availability of soil potassium and on the concentrations of the major cations in an ‘equilibrium soil extract’ are considered.Seedlings grown in soil with a given Na+/K+ ratio in the ‘equilibrium soil extract’ took up much less Na+ than seedlings grown in sand culture where the Na+/K+ ratio in the nutrient solution was the same as that in the ‘equilibrium soil extract’.

Auxin-induced Reversal of Geotropic Response in Onion Seedlings

IN the course of an investigation concerning the germination of onion seeds and subsequent growth of seedlings in aseptic cultures, a striking and unique response to auxin was observed. In normal germination, as observed in Nature or on the basal medium (comprising Heller's minerals and 5 per cent sucrose solidified with 0.7 per cent agar), there is an intercalary elongation of the cotyledon resulting in the emergence of the root and the shoot apex. Due to a curving of the cotyledon the radicular end is carried downward and thus the seedling is established in the soil or on a synthetic nutrient medium. The free end of the cotyledon remains inserted in the seed coat and, as it elongates farther, the seed coat is lifted from the substratum (Fig. 1A).

Population increase of Ditylenchus dipsaci (Kühn) in the narcissus and the spread of the nematode through the soil

SUMMARYA bioassay technique, using forty onion seedlings per pot, was used to determine the soil population of the narcissus race of Ditylenchus dipsaci.In experiments with narcissus, a progressive increase of D. dipsaci populations was shown, reaching a peak at the end of the growing season. This rise in population in May/June was associated with a rise in temperature. Increase in inoculum gave a significantly larger population in the foliage but not in the bulbs. Nematodes moved actively and were transported passively both up and down within the host plant. The presence of spikkels was associated with nematodes in the active intercalary meristem.Migration from the plant into the soil and back into the plant, mostly via the base of the bulb, was continuous throughout the growing season and related to the population increase within the plant. Migration of nematodes from wetted dried leaf tissue continued over 60 days. Spread of the nematode through the soil was slow in the absence of external agencies, such as water run‐off and methods of cultivation.

Growth and Mineral Composition of Vegetable Seedlings

Seedlings of eight species of vegetables were grown in John Innes seed compost. Differences between the mean dry weights of seedlings of the different species shortly after emergence were directly related to differences in mean seed size between species; differences in mineral composition, however, were much greater for the seedlings than for the seeds. Chemical analysis of seedlings of cabbage, lettuce, onion and carrot grown in sand culture confirmed this finding.In sand culture, the dry weight per seedling increased as the K+ concentration in the nutrient medium increased from zero to 8−0 m.equiv.K+/l. although for cabbage and onion the increase was small over the range of 3-5 to 8−0 m.equiv.K+/l. The % K in the dry matter of the seedlings increased with increasing concentration of K+ in the nutrient medium. Both these effects were apparent 3 days after emergence of the seedlings.At about 20 days after emergence, seedlings of lettuce, onion and carrot grown in John Innes compost were smaller and had a lower % potassium content than those grown in sand culture at a K+ concentration of 8−0 or 3−5 m.equiv.K+/l. Cabbage seedlings grown in compost and in sand at the 3−5 m.equiv.K+/l. level were similar in size and composition. It is concluded that seedlings of lettuce, onion and carrot did not take up sufficient amounts of potassium from John Innes compost to sustain optimal growth.

Soil potassium and the growth of vegetable seedlings

AbstractThe rate of growth and the potassium content of seedlings of carrot, lettuce and onion was greater on plets which had received applications of farmyard manure (FYM) than on those which had received only mineral fertilisers (including potassium sulphate at 150 Ib. of K per acre).To find the reasons for these differences the effects of applications of potassium sulphate at rates of up to 800 lb. of K per acre on the availability of potassium in the soil, and on the growth and mineral composition of the seedlings, have been studied.The exchangeable potassium content and the energy of exchange for the replacement of calcium with potassium (ΔF value) after application of 400 lb. of K per acre were similar to those in soil which had received FYM annually for 8 years.Seedlings took up similar amounts of potassium whether the soil had received FYM or 400 lb. of K per acre. Growth of seedlings on the fertiliser‐treated soil was adversely affected when the rate was more than 200 lb. of K per acre. The interactions K/Ca and K/Mg are discussed in this connexion.Fixation of added fertiliser‐K could explain the relatively poor growth response of crops at Wellesbourne to rates of application of fertiliser‐K of about 100 lb. of K per acre.The need to maintain soil‐potassium reserves at a high level for vegetable growing is emphasised.

Modified Bio-assay for Growth Substances in Bulbing Onions

THE onion seedling section assay developed by Clark and Heath1,2 estimated the effectiveness of known and unknown growth substances extracted from onion plants, both before and after photoinduction, and separated by paper partition chromatography; it depended on bulb development in isolated 13-mm. sections cut from onion seedlings at the second leaf (6-wk.) stage. The special significance of this bio-assay was that it tested the ability of these substances to produce the effect under investigation, namely, bulbing, in standard onion tissue maintained under otherwise non-inductive conditions. Clark and Heath showed that indolyl-3-acetic acid (IAA) supplied externally to the sections, as a 1 × 10−4 M solution in the presence of 1 per cent sucrose, caused a significant increase in bulbing ratio (that is, ratio of maximum diameter of base to minimum diameter of neck) after periods of exposure to the test solutions for as long as nine days. No significant changes were found in sucrose alone. The variety used by them, Unwin's Reliance, proved to give rather variable and small responses, and we decided that a more uniform test material was required.

Studies in the Physiology of the Onion Plant: V. AN INVESTIGATION INTO THE GROWTH SUBSTANCE CONTENT OF BULBING ONIONS

Extracts have been prepared from induced and non-induced onion plants. These extracts have been fractionated and the ether-soluble, acidic components investigated using the wheat coleoptile straight-growth assay, colorimetric determination of 3-indolylacetic acid (IAA), and a new bioassay which has been introduced and modified to give reproducible results. This last is an assay of substances which will cause ‘bulbing’ (swelling of the leaf bases) of onion plants, and it has been used to demonstrate a number of factors which influence the initiation of bulbing in the onion. It has been shown that substances are present in extracts of onion tissue which will cause an increase in the ‘bulbing ratio’ of test onion seedling sections. Results indicate that there is an increase in the IAA content to a very high level during the first week following induction—before there is any visible sign of swelling of the leaf bases—but that this falls off rapidly after 5–7 days and eventually falls below the level found in non-induced plants.

Seed disinfection

Tests were carried out to investigate the effect of various fungicides on viability of onion seed in storage, and on emergence of onion seedlings in glasshouse and outdoor soils.

Observations On the Life Cycle of Ditylenchus Dipsaci On Onion Seedlings

Ditylenchus dipsaci was raised on onion seedlings and its life cycle investigated in detail. A suitable technique was evolved by which the different stages of the nematode could be inoculated inside the plant tissue to observe their development. The total duration of the life cycle ranged from 19 to 23 days, with four moults and four larval stages. The egg stage lasted 7 days, first-stage larvae inside the egg from 5-51/2 days, second-stage 2-21/2days, third-stage 3-31/2 days, and fourth-stage 4 to 5 days. The first moult takes place inside the egg and the hatching larva is the second-stage larva. The various larval stages are distinguishable by their total length and by the nature and location of the genital primordium. The sexes can be differentiated in the third and fourth-stage larvae as well as adults. Mating is necessary for reproduction and the female starts deposition 4 days after the final moult. A single male was able to fertilize more than one female. Egg-laying capacity of individual females ranged from 207 to 498 eggs. Longevity of both the males and females was observed to be 45 to 73 days.

Effects of nitrogen supplied for the various stages of growth, on the growth and yield of onions in the sand culture

Experiment were carried out to clarify the effects of nitrogen supplied for the various stages from transplanting to harvesting time, on the growth and yield of onions in the sand culture. In both 1952 and 1955, onion seedlings (Yellow Danvers sown early in September) were transplanted late in No-vember and harvested late in next June, Results obtained were as follows. 1. The bulb yields of plants which were stopped nitrogen supply since middle or late in May (completing stage of top growth) were equal to, or rather exceeded that of control plants supplied with nitro-gen until harvesting time. Plants which were dis-continued nitrogen supply since middle or late in April (beginning stage of bulb thickening), were decreased to some degree in both top growth and bulb yield. And in the treatments in which nitrogen sup-ply were discontinued on and before middle or late in March (beginning stage of top growth), top growth and bulb yields were reduced remarkably, and their bulbs were round-shaped in contrast with flatshaped in the control. 2. Plants which were withheld nitrogen supply until late in February or early in March, and since then supplied with nitrogen, recovered their retar-dation of top growth rapidly and their bulb yields made no great difference compared with that of control. But when nitrogen supply was withheld until late in March, or late in April, bulb yields in these treatments could not catch up with that of control until harvesting time. 3. The treatments of cutting off the nitrogen sup-ply for about one month in the various stages of growth, had no effect on bulb yields at harvesting time. 4. In the tops of control plants, nitrogen and dry matter contents were lower until late in Febru-ary, and increased from Mach to May, especially the increment in April was remarkable. In the bulbs, nitrogen contents increased rapidly together with dry matter contents from middle or late in April, and continued to increase until harvesting time. 5. From results obtained, it is concluded that nitrogen supply from middle or late in March to middle or late in May is most important for growth and yield of onion, while nitrogen supply after late in May, or before early in March is not so import-ant as that for the above-mentioned period.

The Effects of Chlordane and Toxaphene on Mitosis in Roots of the Onion (Allium CepaL.)

Experiments were carried out with technical chlordane and toxaphene to ascertain whether, employed as insecticides, they had any effect on cell division. Root-tips of onion seedlings were used as test material and the doses used were equivalent to 20 and 200 lb. per acre of 10 per cent, dusts on gypsum. By germinating onion seeds in direct contact with the insecticide under investigation, it was shown that neither chlordane nor toxaphene affected germination, but chlordane reduced the growth rate. The frequency of nuclear divisions was unaffected by toxaphene, but reduced by chlordane. Both compounds affected the dividing cell by causing a delay in pro-metaphase and preventing nuclear reconstruction in telophase. In addition, chlordane had a lethal effect on the resting cell. The effect on telophase was evident for a period of at least four days after removal from the insecticides.Pot experiments showed that the low dose of toxaphene had little effect on cell division, but the low dose of chlordane and th...

METHYL BROMIDE AS A SOIL FUMIGANT FOR CONTROLLING SOIL-BORNE PATHOGENS AND CERTAIN OTHER ORGANISMS IN VEGETABLE SEEDBEDS

The effectiveness of methyl bromide (Dowfume MC-2, 98% methyl bromide and 2% chloropicrin) as a fumigant for controlling diseases in seedbed soils used for the production of vegetable seedlings under glass was studied. A differential response of the microfloral components of a sandy loam compost soil to the lethal action of methyl bromide was observed. In general, fungi were destroyed at lower concentrations than were bacteria and actinomycetes. Of the pathogenic fungi tested, Fusarium oxysporum f. niveum and a Fusarium sp. causing root decay of onion seedlings were found to be the most resistant to the lethal action of methyl bromide. Whereas the former was destroyed by a dosage of [Formula: see text]. per 100 cu. ft. in sandy loam soil and the latter by a dosage of 2 lb. in muck soil, Pythium sp. Rhizoctonia solani, and several other pathogenic fungi were destroyed by a much lower dosage, namely, that of [Formula: see text]. per 100 cu. ft. Bacteria showed a broader range of variability than the fungi in their tolerance of methyl bromide. Whereas Xanthomonas vesicatoria and Rhizobium trifolii were destroyed at dosages of 1–2 lb. per 100 cu. ft., Pseudomonas tomato occurring in shallow lesions on tomato fruits and several spore-forming bacteria occurring in the soil were not destroyed at dosages of 4 lb. per 100 cu. ft. The benefits derived from the fumigation of a sandy loam compost soil with methyl bromide were reflected not only in the freedom of vegetable seedlings from disease but also in their increased and uniform growth. Some vegetables showed greater growth in fumigated than in steam-sterilized soil, whereas others showed the opposite effect.

The Effect of Hexachlorocyclohexane on Mitosis in Roots of the Onion (Allium Cepa) and Strawberry (Fragaria Vesca)

Experiments were carried out with a proprietary flea beetle dust containing crude BHC to ascertain whether, employed as an insecticide, it has any effect on cell division. Root-tips of onion seedlings and strawberry runners were used as test material and the doses were equivalent to 40–200 pounds per acre of flea beetle dust. By germinating onion seeds in direct contact with the insecticide it was shown that it has two effects on the chromosomes. The frequency of nuclear divisions was unaffected, but low doses may lead to the exclusion of nuclear fragments in subsequent cell divisions and higher doses may lead to polyploidy. Both effects were produced by the dust and the gamma and delta forms of BHC when used separately. The alpha and beta forms were only slightly active in high concentrations. The milder effect was particularly evident for a period of at least four days after removal from the insecticide.In a series of pot experiments it was shown that relatively high doses had only a slight effect on ce...

Test on the weed control on the upland field by the use of I. P. C. (1)

(1) Effects of I. P. C., a chemical herbicider of graminous weeds, have been tested since the spring in 1949. (2) Although the tests were ended in failure frequently at summer season. In October when seedling of onion, spinach and graminious weeds grew up about 3∼7 cm in height, water solution ot 0.67% I.P.C. at the rate of 15∼22.5 liter per are (100∼200g of I.P.C. was used per are) were sprayed over the field. It was proved that this water solution was so effective a selective weed killer that raminous weed were all killed ter solution was so effective a selective weed killer that raminous weed were all killed within 2∼3 days without damage to seedlings of onion and spinach, and no weeds grew there after. (3) However, oil solution of 4% I.P.C. at the rate of 0.75∼1.5 liters per are (30∼60 g of I.P.C. was not only weeds but also the crop all together, therefore oil solution of of I. P. C. was not recognized to act selectively. (4) It is noted also that the effect of I.P.C. is not remarkable for the grown up graminous plants. (5) On November 18th, immediately after the seeds of pea, broad beans, rape, wheat and barley were sown, 100∼150 g of I.P.C. water emulsion and 30∼60 g of I.P.C. oil solution per are were sprayed over the field. (6) In this series of experiments, it was found that in plot where more than 60 g of I.P.C. was used, no weed was seen for 40 days and after 135 days, the quantity of weeds was only 1/5∼1/(50) as compared with that of the untreated plot. There was no damage on the germination and the growth of pea, broad bean and rape, while barley and wheat grew very sparsely. (7) It was concluded from the results that I.P.C. was a effective weeder acting selectively on the Graminious plants only. It was also noted that pretreatment of soil with I.P.C. was most effective and its application to young weeds also gave considerably good results.