Side Shoots Research Articles

Apex Removal and Single-harvest Yield of Side Shoots of Broccoli1

Abstract Hand pinching of newly initiated central heads of two cultivars of broccoli (Brassica oleracea L. Italica group) resulted in uniform development of several side shoots, enabling a single harvest of high-quality side shoots. The yield of side shoots of ‘Waltham 29’ was higher than the yield of central heads of nonpinched plants. For ‘Green Duke’, no difference in yield was found due to treatment. The time of pinching was crucial with ‘Waltham 29’ but not with ‘Green Duke’.

Growth of side shoots in brussels sprout plants as influenced by GA3 and defoliation.

Field-grown brussels sprouts were either treated once with GA3 at 0-27 mg/plant or were defoliated on 10 fortnightly dates between 25 May and the end of September. GA3 markedly stimulated side shoot growth at most application dates, the maximum effect being obtained with the highest rate applied on 8 June. Defoliation on most dates had little stimulating effect on side shoot growth, but when carried out on 3 August the effect was marked. [For previous related work see HcA 41, 8833.]. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The Effect of Environmental Parameters on the Germination, Growth, and Development of Suaeda depressa (Pursh) Wats

A study was made to determine the effect of environmental parameters on the germination, growth, and development of Suaeda depressa (Pursh) Wats. Germination tests showed that seeds germinated in solutions containing up to 4 % NaCl with no toxic effects indicated after treatment with distilled water. The rate of germination and the percentage germination decreased with increased salinity. The effect of environmental parameters on growth was measured by shoot height, side shoot development, leaf length, and dry weight. Growth was greatest in 1 % NaCl solutions with adequate available nitrogen. With increased salinity and low available nitrogen levels plant growth decreased. A 10-hr photoperiod stimulated immediate floral induction. Although flowering and completion of the life cycle occurred in solutions containing up to 4 % NaCl, increased salinity decreased the rate of floral induction and the dry weight of flowers and fruit produced. This study indicates that environmental parameters such as salinity, available nitrogen, and photoperiod can create a variety of growth forms, causing taxonomic confusion.

THE EFFECT OF ENVIRONMENTAL PARAMETERS ON THE GERMINATION, GROWTH, AND DEVELOPMENT OF SUAEDA DEPRESSA (PURSH) WATS

A study was made to determine the effect of environmental parameters on the germination, growth, and development of Suaeda depressa (Pursh) Wats. Germination tests showed that seeds germinated in solutions containing up to 4 % NaCl with no toxic effects indicated after treatment with distilled water. The rate of germination and the percentage germination decreased with increased salinity. The effect of environmental parameters on growth was measured by shoot height, side shoot development, leaf length, and dry weight. Growth was greatest in 1 % NaCl solutions with adequate available nitrogen. With increased salinity and low available nitrogen levels plant growth decreased. A 10‐hr photoperiod stimulated immediate floral induction. Although flowering and completion of the life cycle occurred in solutions containing up to 4 % NaCl, increased salinity decreased the rate of floral induction and the dry weight of flowers and fruit produced. This study indicates that environmental parameters such as salinity, available nitrogen, and photoperiod can create a variety of growth forms, causing taxonomic confusion.

Effects of nutrition and hormones on growth and apical dominance in tea (Camellia sinensis(L.) O. Kuntze)

SummaryThe effects of three levels of a widely used tea nursery fertilizer mixture containing थ, ऩ,ρढ, Mg and SO4 and hormones on growth and apical dominance were studied using free-growing plants of two vigorous TRI clones.At the highest level of fertilizer (F2) the plants showed earlier bud-break and an increase in the number and duration of active phases, with a reduction of the dormant phases. These resulted in more growth and dry matter accumulation and in more lateral shoot growth than was obtained with lower levels of fertilizer (FO and Fl). Leaf production on both main and side shoots was increased at the higher levels of nutrition. The results showed that vigorous clones may benefit from higher levels of fertilizer application than the presently recommended rates.Gibberellic acid (200 ppm) alone or with benzyl adenine (25 ppm) tended to cause earlier bud-break at FO and Fl but not at F2. The percentage bud-break obtained at F2 was, however, similar to that obtained at FO and Fl with the above hor...

Growth retardation in side shoots of brussels sprout plants.

In 2-year studies bud cuttings were taken from Sandra brussels sprouts plants at 2-week intervals from 19 May to 6 October and grown in continuous light at 15 degrees C. The stem length of 12-week-old plants declined progressively with successive plantings up to 11 August and thereafter increased progressively. With field-grown plants (planted on 10 May) the growth rate of a long side shoot (assessed at intervals between 14 July and 15 December) was slow until the end of July, increasingly rapid until 22 September and thereafter progressively slower.-Agric. Univ., Wageningen. (Abstract retrieved from CAB Abstracts by CABI’s permission)

SEGREGATION OF COMPACT GROWTH TYPES IN CERTAIN APPLE SEEDLING PROGENIES

Two-year-old apple seedlings of six progenies resulting from crosses between cultivars of standard growth or their compact mutants were classified for standard or compact growth type. A natural compact mutant of McIntosh (Wijcik) in combination with Golden Delicious transmitted compact growth habit to 43.9% of its progeny, whereas the radiation-induced compact mutant of McIntosh (8F-2-27), in the same combination did not transmit this characteristic. Number of side shoots, internodal length, and the ratio of length to diameter of one-year-old shoots were useful characteristics in distinguishing between the standard and compact growth types in two-year-old seedling trees. As the segregation of seedlings of compact growth habit is of great interest both from theoretical and practical aspects, a careful assessment of the transmissibility of compactness by mutant and non-mutated cultivars in various cross-combinations is suggested.

Graft-transmissio of male sterility in sugar beet (Beta vulgaris L.)

Cytoplasmic male sterility in sugar beet was successfully transmitted across the union where male sterile and equivalent O-type plants were reciprocally grafted. Two experiments are described. In the first, 30 pairs of developing flowering stems were exchange-grafted between male-sterile and O-type plants. Fifteen O-type scions exhibited full or partial male sterility when grafted to male-sterile stocks and sterility was observed in progeny from these in eleven cases. In flowers from side shoots of O-types grafted with male-sterile scions eight cases exhibited some male sterility and progeny from four of these retained the sterility. In the second experiment O-type seedlings were grafted to male-sterile seedlings and out of the 22 success-fully raised to flowering, male sterility was exhibited in 12 of them. Male sterility occurred among progeny of all 22, even where the sterility could not be detected in the scions. In six cases where the scion appeared fully male-sterile no pollen was produced in any of the progeny.

The Gametophore and Sporophyte of Mittenia plumula (Mitt.) Lindb

An account is given of the gametophore and sporophyte of Mittenia plumula, stressing those features which have not previously been described. The moss has a highly refractive lenticular protonema. There is variation in the arrangement of leaves on sterile and fertile shoots, a shoot may develop one or more side shoots at its base, and hairs are present in the axils of leaves. The capsule has a few small stomata at the base, and the inner peristome consists of 28-32 processes. The double peristome of Mittenia plumula originates from three concentric layers of cells, the two innermost layers of the amphithecium and the outermost layer of the endothecium. In all other members of the Bryales whose examination has included early development, the peristome has been found to develop from amphithecial tissue only. The 16 outer peristorno teeth are forined on the periclinwl walls separating the two outer peristome layers, thickening being laid down on the inner walls of the outer layer, which is composed of 16 cells, and in adjoining posit'ions on tho outor walls of the middle layer, which is composed of eight cells. The inner peristome processes are formed on the periclinal walls separating the middle from the inner peristome layer (the latter being endothecial in origin). Thickening is laid down on the inner walls of the middle layer at positions contiguous with the junctions of the anticlinal walls of the inner layer, which is composed of 24-28 cells. Extra processes usually develop where the anticlinal wall is part of the original quadrant wall of the embryo. A smaller amount of thickening is then contributed to the processes from the inner peristome layer. Variations in the development of the inner peristome are discussed, and a comparison is made with development of the double peristome of other members of the Diplolepideae.

Studies on udo, Aralia cordata THUNB. III

Stocks of domestic and wild udos (Aralia cordata THUNB.), collected from various districts in Japan, have been cultivated in Sakai, Osaka Pref., and studies were made chiefly on their morphological characters with regard to the variations among the domestic and wild udos. Wild udos showed a wide range of variations as a whole, and their geographic variations seemed to be related to the latitude or altitude. They can be grouped into two types; the northern type and the southern type. The plants of the northern type, which are found in Hokkaido and Tohoku districts, have shorter hairs on their stems, less developed stipules, and less numbers of nodes, side shoots, and leaflets of the compound leaves, owing to their earlier blooming, than the plants of the southern type, which are growing in Kansai and western districts of Japan. In domestic udos, however, the range of varietal variation is not so wide, and all varieties observed are found to resemble to the wild udos of the sou-thern type. “Kan-udo”, which has short rest period and can be easily forced early in the season, was said to be introduced from Hokkaido. Our observations, however, revealed that it belonged to the southern type, basing on its morphological characters.

What substance normally controls a given biological process?: II. The relation of auxin to apical dominance

1. 1. Reviewing the literature on apical dominance in the light of the “PESIGS” rules formulated in the preceding paper (Jacobs, 1959) made clear that earlier researchers had never demonstrated exact substitution of synthetic auxin for the native auxin of the apex. 2. 2. Our clone of Coleus blumei Benth. shows apical dominance: excising the top of the main shoot induces greater growth of the younger side shoots. 3. 3. One per cent indoleacetic acid in lanolin exactly substitutes for the top of the main shoot in providing auxin through node 2, in causing faster abscission through node 4, and in causing xylem regeneration in internode 2. And yet this 1% IAA in lanolin has no inhibiting effect on the growth of the side shoots. 4. 4. We conclude that contrary to the classic theory, apical dominance in Coleus is not controlled by auxin from the apex.

SEPTORIA CANKER OF INTRODUCED AND NATIVE HYBRID POPLARS

Studies have shown that Septoria musiva Peck, a North American fungus which occurs commonly as a leaf-spotting parasite on native poplars, produces cankers, in addition to leaf injury, on certain introduced poplars (Populus Rasumowskyana Schneid., P. Petrowskyana Schneid., and P. berolinensis Dipp.), and the native hybrids, Northwest and Saskatchewan poplar.Field observations and inoculation experiments demonstrated that most of the inoculum for spring infection arises from ascospores of a Mycosphaerella stage, and that the fungus enters the stems through mechanical wounds uninjured lenticels, leaf petioles, or stipules. Incipient cankers occur in the bark of the current year's wood, soon girdling leading and side shoots. They later spread from lateral branches into the main stem, developing into perennial cankers which ultimately girdle and kill the trees.

Influence of Sulphur Deficiency on the Metabolism of the Soy Bean

1. The effects of sulphur deficiency were studied in the soy bean. It took considerable time for symptoms of sulphur deficiency to become apparent, but they were beginning to show in four weeks' time and had become pronounced in six weeks. 2. The main symptoms were the yellow-green color of the leaves, the smaller leaflets, and the thinner stems. These symptoms are similar to those that have been noted for other elements, for example, nitrogen, potassium, and phosphorus. This no doubt indicates a similar cause, namely, poor nitrate assimilation. 3. The upper leaves become yellow first. This is similar to the effect of sulphur deficiency in the tea bush and to calcium deficiency in the tomato, but is in contrast to deficiency of nitrogen, potassium, or sulphur in the latter plant. In the case of the latter elements, the lower leaves become yellow first. 4. Stem elongation was a prominent feature of both plus and minus sulphur plants because of the use of electric lights for part of the light period. Omitting sulphur from the nutrient solution caused some reduction in the height of the plants, but still the stems elongated remarkably. This is in contrast to the deficiency of other elements and is no doubt correlated with the ability of these plants to break down and reutilize proteins. 5. Sulphur deficiency affected the tops of the plants more than the roots. This is similar to the effects of nitrogen deficiency and also to some of the results reported for phosphorus deficient plants. 6. The stems of the minus sulphur plants were harder than those of the plus sulphur plants. Cell wall thickness has been found correlated with an accumulation of carbohydrates. In the case of the soy bean, it seems more correlated with the accumulation of starch and hemicelluloses than with all forms of carbohydrates. 7. Characteristic symptoms of boron deficiency appeared in a number of the plants grown in 1933. The numbers of plus sulphur and minus sulphur plants showing this injury were about equal. The addition of boron caused the quick formation of side shoots. It is not thought that boron deficiency affected the differences in the plus and minus sulphur plants. 8. The plus sulphur plants were more succulent than the sulphur deficient plants. In this they were like plants grown with plenty of nitrates in the nutrient solution. 9. Nitrates accumulated in the minus sulphur plants. This was because of poor nitrate assimilation. Deficiency of other elements may also cause this. It would be expected that in such circumstances carbohydrates would also accumulate. Starch and hemicelluloses were higher in the sulphur deficient plants, but sugars accumulated in the plus sulphur plants. Sulphur deficiency apparently affects the form of carbohydrate accumulation in the soy bean. This is in contrast to the tomato, in which all forms of carbohydrates accumulate in the minus sulphur plants. 10. There is some evidence that hemicelluloses serve as reserve food materials in the soy bean. 11. The soluble organic nitrogenous fractions were higher in the minus sulphur plants, especially in the stems. This was at least partly due to proteolysis, and is important in accounting for the stem elongation of the minus sulphur plants. When proteolysis occurs, there is usually also a decrease in carbohydrates. The sulphur deficient plants were higher in starch and hemicelluloses but lower in sugars; therefore the proteolysis which occurs is of a special type. But since the minus sulphur plants are lower in sugars, these plants may perhaps be regarded as more in accord with the usual situation accompanying proteolysis than sulphur deficient tomato plants, in which all forms of carbohydrates accumulate. 12. Accumulation of the soluble organic nitrogenous fractions in the minus sulphur plants no doubt was partly due to the new synthesis of these compounds and the failure of the completion of protein synthesis because of the lack of sulphates, for nitrate reduction may no doubt go on slowly in sulphur deficient plants. This may have a bearing in explaining the somewhat abnormal situation in regard to the accumulation of carbohydrates during proteolysis. 13. Similar symptoms of sulphur deficiency were noted in the sunflower, kale, rape, and mustard. The influence of sulphur deficiency in reducing the mustard oil content was definitely evident in the mustard. The leaves of the minus sulphur plants were not nearly so acrid in taste as those of the plus sulphur plants.

A TRANSMISSIBLE VIRUS DISEASE OF THE EASTER LILY

Summary. A summary is given of the history of the Bermuda Easter lily (Lilium longiflorum var. eximium Baker), known to the trade as “Lilium Harrisii.” It is known that about 1893 “a peculiar sickness” appeared in the lily fields of Bermuda, which caused a very marked decline in the yearly amount of bulbs exported from the Colony. Subsequent to 1919 a resuscitation of the industry has taken place, and especially in recent years, when the chief cause of its failure has been ascertained. A summary of the methods of cultivation in Bermuda is given. Theories as to the cause of the disease were put forward by Woods, Bishop, and others. It is shown that there were two types of disease, one resembling a mosaic, the other characterised principally by very marked stunting and downward curling of the leaves. The latter is here dealt with. Photographs taken in the United States Department of Agriculture greenhouse at Washington in 1915 show clearly examples of the disease. The disease came prominently to the notice of the writer in 1925 when certain aspects of it suggested that it was a virus disease. It was called “yellow flat” by the grower who first observed it. The general appearance of a plant grown from an infected bulb is a flat rosette or cylinder. The leaves are very markedly curled downwards and are slightly chlorotic in colour, but without streaks or spots. In current season infection the leaves which are mature at the time of infection do not show the symptoms. The young leaves show considerable twisting besides curling. Plants from affected bulbs do not show the symptoms till about 4 weeks after coming above ground. Transmission experiments are described in which positive results were secured by the use of Aphis gossypii Glover. Experiments with the following were unsuccessful: Aphis Ogilviei Theob., Macrosiphum gei Koch., Neotoxoptera violae Perg., and Pseudococcus citri Risso. Attempts at mechanical transfer were also unsuccessful. There is no evidence that the disease is carried in the soil. Aphis gossypii is described. Its biology is discussed. It is parasitised by Lysiphlebius (Aphidius) testaceipes Cress, and attacked by certain Coccinellids, larvae of Syrphids, etc. Spread of the disease takes place mainly early in the season. Affected plants occur in patches in the fields, the average number of infected plants round a bulb‐infected plant being about 15.It appears that the disease is transmitted to the scales and side shoots of affected plants.Affected plants begin to die down about flowering time, about two months before healthy plants.The root system is affected and is attacked by secondary organisms, fungi and the bulb mite.Bulbs from affected plants are flat, small and compact, and resemble bulbs of poor types of Lilium longifiorum.There is a marked tendency to splitting of the bulbs, so that in successive years smaller and smaller bulbs are produced. Amongst weeds or in shady situations the affected plants are not so markedly stunted.Plants from affected bulbs seldom produce flowers. In current season infection the number of flowers is considerably reduced, the flowers twisted and blistered and the pedicels turned stiffly downwards. In the writer's opinion recovery from the disease never occurs. At temperatures of about 70° F., under greenhouse conditions, the internodes are often lengthened and the leaves twisted rather than curled. The disease has been observed on “Lilium formosum” and “Lilium giganteum” and apparently occurs in Japan. It is apparently not connected with any virus diseases of other plants occurring in Bermuda. Similar symptoms brought about by other causes are described. The disease was probably introduced into Bermuda from Japan about 1893, either direct or via the United States. The means of control recommended are roguing, spraying with contact insecticides, and clean cultivation. The official inspection carried out by the Government since 1925 has already reduced the disease to a practically negligible quantity.19. The disease is compared with other virus diseases. It is apparently the first virus disease of bulbous plants to be fully described.