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WINTER PROTECTION.

The Globe artichoke needs protection during the coldest part of the winter. Fresh manure was tried on the Station beds but with disastrous results in that, either by heating or by retaining too much water, it caused the heart of the crowns to rot, with consequent death of the plant. Coal ashes were then used, with success. The foliage is semi-hardy and should not be covered until late in November, and the covering removed in spring in late March or early April. Before mounding with ashes (Plate LXIV) the leaves must be cut back to within a foot of ground and drawn in about the

In the spring when the covering is removed the small leaves will be found to be in a blanched condition, but soon turn green and are followed by new leaves from the crown.

crown.

INSECT AND FUNGUS TROUBLES.

The plants on the Station grounds have been free from all fungus attacks.

A black aphid or louse is troublesome at times, literally covering the undersides of the leaves, and occurring especially during midsummer. This insect may be controlled by spraying thoroly with a dilution of Black Leaf 40 and whale-oil soap, the formula being 1 ounce of Black Leaf 40 and 4 ounces of whale-oil soap to 8į gallons of water. It is necessary to spray the lower surfaces of the leaves and about the crown of the plant.

USE OF THE GLOBE ARTICHOKE.

The artichoke must be considered a luxury rather than a staple. Both on account of this fact and on account of the large amount of ground space required per plant -- 16 square feet — this vegetable has no place in a very small garden, especially in years of shortage of staple foods. However, to many people the artichoke is a muchdesired delicacy and is eaten almost every day during fruiting season. The edible portion is the immature flower bud and which may be prepared for the table in many different ways. The following recipe is very satisfactory.

BOILED ARTICHOKES.

Whatever portion of the stem remains should be cut away from the bud, the large outside bottom leaves or bracts removed and imperfect ones trimmed. The heads should then be placed in cold water for one-half hour. Drain and cook one-half to one hour in salted boiling water to which has been added one tablespoonful of lemon juice or vinegar for each quart. When tender, drain and serve with melted butter, pepper, salt or any of the salad dressings. Of the large outer leaves only the small fleshy base is useful but the center leaves are tender almost to the tip. The spiny center called the choke is not edible. After the bracts and choke" are removed the fleshy base remaining may be eaten.

INHERITANCE OF SEX IN STRAWBERRIES.*

R. D. ANTHONY

UNDER THE DIRECTION OF

U. P. HEDRICK.

SUMMARY The fact that several investigators are using the strawberry in a study of sex inheritance has made it seem advisable to publish certain data referring to this problem that have been secured during nearly thirty years of strawberry breeding at this Station.

The seedlings have been grouped under three classifications: perfect, imperfect and semi-perfect. A sharp line can be drawn between perfect and imperfect plants only after careful observation which, in doubtful cases, should extend through two seasons. The production of perfect blossoms is sometimes delayed till the plant is in nearly full bloom. Conditions leading to lack of vigor in the plant seem occasionally to suppress stamen development in perfect sorts throughout the entire season.

In general, there are two types of imperfect blossoms: those with stamens absent or rudimentary and those with filaments at least partially developed but anthers abortive if present.

Perfect varieties vary widely in the number of stamens and the amount of pollen they produce.

Pure male plants have been noted by others but none has been recorded among the thousands of plants grown at this Station.

Some Station seedlings have probably been classed incorrectly · as imperfect but it is doubtful if such cases are numerous enough materially to influence the results.

When imperfect varieties have been pollinated by perfect sorts the resulting seedlings are of the two types in practically a i to I ratio.

The results secured when two perfect sorts have been crossed are: 2190 perfect, 9 semi-perfect, 5 imperfect. The five imperfects may be regarded either as representing errors in observation or as being the product of abnormal perfects.

The seedlings secured by self-pollinating perfect varieties differed materially from those from cross-pollinated perfects. There were 3159 perfect, 685 semi-perfect and 474 imperfect. All of the imperfects were secured from eight perfect varieties. The results with four of these are considered in a discussion of abnormal cases.

Of the seven cases in which abnormal results would seem to have been secured, five involved Marshall blood in varying degrees.

*

Reprint of Technical Bulletin No. 63, September, 1917.

Quality, when selfed, produced a larger proportion of imperfect seedlings than any other variety. One of these was tested in the greenhouse and produced no pollen even under such favorable conditions. When this seedling was pollinated by a perfect seedling of the same parent 31 perfect and 43 imperfect seedlings were obtained. When the seedling used as a male was self-pollinated all the progeny were perfect.

The results suggest that the best method of attacking the problem would be to grow pure seedlings of a considerable number of Fı and F, seedlings of both Marshall and Quality.

As the further development of the problem of the inheritance of sex involves work not well suited to a department of horticulture it is being discontinued and the results published in their present incomplete form.

HISTORY Since the strawberry is being used by a number of investigators in the study of sex inheritance it has seemed advisable to publish certain data secured at this Station not so much because of the light they may throw on this subject but more to call attention to some of the problems involved.

Strawberry breeding was begun at Geneva in 1888. Of the many thousand seedlings produced since then nearly two thousand have seemed worthy of retaining beyond the first test but only twelve of these have finally been named and distributed. During most of this time the study of sex has been incidental but for the last four years an effort has been made to get more definite information than had previously been secured and especially to study certain crosses which seemed to give results at variance with those previously obtained.

TYPES OF PLANTS. Through the early years all seedlings were grouped under two classifications: Perfect, those with both pistils and stamens, and imperfect, those with pistils only. During the last ten years those plants have been classed as semi-perfect the flowers of which possessed stamens but which produced so little pollen as to seem incapable of self-pollination.

One of the first results of this work was the belief that a sharp line can be drawn between perfect and imperfect plants only after careful observation of all blossoms throughout the season and in doubtful cases through a second season and that even then there is a likelihood of some plants being classified as imperfect which might produce pollen under more favorable circumstances. Not infrequently all of the opened blossoms on plants which are in nearly full bloom will have rudimentary or abortive stamens yet an inspection of buds just ready to open will show a full complement of functional stamens. Beyond doubt a number of plants were incorrectly entered in our early records as imperfect because of this delayed production of perfect flowers. In several cases in recent years plants which were recorded as imperfect in a field test have produced pollen and even formed perfect fruits under self-pollination when grown in the greenhouse with more favorable environment. Conditions leading to lack of vigor in the plant seem occasionally to suppress stamen development.

Imperfect blossoms can, in general, be divided into two groups: those in which the stamens are entirely absent or where the rudimentary filaments are represented by mere points, and those in which the filaments are present and at least partially developed but any anthers formed are abortive. It is in this second group that we will usually find those perfects which, because of abnormal behavior, have been incorrectly recorded as imperfect.

Among perfect varieties there is a wide range in the number of stamens produced and the abundance of pollen in the anthers. A final solution of some of the problems involved in the study of sex may make necessary the grouping of the perfects according to their pollenproducing power. This has not been done as yet at this Station.

Richardson 1 described pure male plants and seemed to find them produced rather commonly in certain of his crosses. No pure male has ever been noted among the thousands of plants grown at this Station.

GENERAL RESULTS. In the follɔwing discussion it should be borne in mind that the term imperfect has probably been used in some cases where a more extended study of the individual would have proved it to be perfect. It is doubtful if such cases are numerous enough to influence the results to an appreciable extent. All the parents have been under observation long enough so that there is little doubt of the correctness of the terms used in describing them.

Imperfect X perfect: Summing up all crosses where imperfect blossoms have been pollinated from protected perfect blossoms, 1591 of the resulting seedlings were perfect and 1621 imperfect, practically a 1 to 1 ratio. In the list of crosses entering into this total it will be noted that there are but few cases where the fluctuations from this ratio are extreme.

1 Richardson, C. W. A preliminary note on the genetics of Fragaria. Journ. Genet. 3:171-177.

2 Attention should be called to certain unpublished results of two other investigators. Of the 1013 seedlings obtained by W. C. Stone at the Vermont Station by crossing imperfects with perfects, 659 were imperfect, a ratio of 1 to 1.86. From the Ontario (Canada) Agricultural College Prof. J. W. Crow reports the following: Warfield (imp.) x Parsons.

211 perfect, 122 imperfect Buster (imp.) x Williams..

144 perfect, 140 imperfect It is possible that all varieties do not behave alike in this type of cross and that the varying results are due to factors other than experimental error. The behavior of Marshall and Quality as shown later in the report lends color to this idea.

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