USPP213P - Hybrid poplar - Google Patents

Description

Jan. 5, 1937.

R, H. M KEE HYBRID POPLAR Plant Pat. 213

Filed June 28, 1935 Fig.

[river Jar W [aw/w cnQrQwk Hirer/1g Patented Jan. 5, 193

UNITED STATES BEST AVAILABLE coPY PM Pat. 213

PATENT OFFICE 1Claim..(Cl.47.-59)

This invention relates to a new and distinct hybrid poplar and more particularly to a hybrid poplar which has a very rapid rate of growth, which is substantially immune to the ordinary diseases to which poplars are susceptible, and the woodof which is particularly suitable for use in makin pap r pu p.

This is a division of my copending application Serial No.'477,979, filed August 26, 1930.

As is well known. poplar wood is one of the.

most valuable woods for use in-the making of wood pulp. At the present time there are known in the United States and foreign countries, according to Illick (1924) and to Sargent (1922), approximately thirty varieties of poplar and five commonly recognized hybrid poplars. Dode (1905) lists 110 species but the accuracy of this is questioned. Only two species of these are commercially useful for pulpwood. The commonly recognized hybrids include the Lombardy poplar (male), Regenerata poplar (female), Carolina poplar (eaaenei) (male) and Robusta poplar (male) the parent trees of which are not definitely known. The fifth of the hybrid poplars known as P. (Populus) gcnerosa which was first obtained in England in 1912, had as its male parent P. trichocarpa and as its female parent P. balsamijera virainiana (sometimes termed P. angalata) As stated, these hybrids were known prior to the present invention and are disclaimed as forming no part of the invention.

Due to the increasing consumption of poplar wood in cellulose industries, and the resulting decreasing supply, it is obviously desirable to provide abundant sources of poplar wood for future consumption. However, several disadvantages attend the reforestation of land with ordinary poplars. For example, ordinary poplar species used commercially, such as P. tremuloides and P. arandident'ata, require many years of growth to provide trees of'suitable size for supplying wood for use in making wood pulp or for lumber, e. g. a tree 12 inches in diameter will ordinarily be 80 years or more old. In addition, for maximum growth of ordinary poplars, a rich soil or the use of fertilizers is required. Further, ordinary poplars are susceptible to numerous common tree diseases, such as Cytospora and Melampsora medusae. Finally, the length of fiber of the wood of ordinary poplars is not so great as might be desired for the making of paper pulp, so that a portion of longer fiber pulp (such as that from spruce) is often added to the poplar pulp to give the paper the desired strength.

The present invention overcomes all of the foregoing disadvantages and provides a new variety of hybrid poplar which not only grows quickly in ordinary soil but is-particularly suitable for supplying wood of high grade for lumber and for use in making wood pulp. 5

When two species of the Populusgenus are crossed seeds are obtained which when grown produce seedlings ofvarying types. Some of these seedlings will be dwarfs, some will grow at the same rate as their parents, and others will grow so rapidly that, relatively speaking, they partake of the nature of giants. The. present invention is concerned with the propagation of thou seedlings whichare giants, i. e. which have a rapid growth rate. In general, it is found that the varieties which are particularly useful are those whose dimensions is more than twice the corresponding dimension of the parent trees. By dimension is meant the height of the tree at the same age, as well as the. diameter of the tree at the same age. In some cases, I have found that the hybrid treeproducedfhas a relative. dimension as great as three timesthe corresponding dimension of the parentvtrees.

In order to obtain seedlings of the desired characteristics as set-forth above! have grown approximately 16,000 seedlings obtained by crossing different varieties of poplars and determined which-of these hybrid seedlings possessed. the characteristics of the desired tree. The better of these seedlings have propagated vegetatively and the desired characteristics were found to continue and show in the trees so produced. vegetatively. This, of. course, isfrequently not true of subsequent generations grown from seed 5 after a hybrid crossing. A portion of this work has been described in the Journal of Heredity, vol. 24. pa es 216-229, in 1933.

Of course. one could not be certain of obtaining trees of the desired characteristics no matter how such work was done. The uncertainty of results is always present in attempting to get by hybridization a particular type of tree. Ordinarily in hybridization one simply makes numerous crosses and picks out the one most interesting. In this particular case, however, I was searching for trees of a particular type and, in general, discarded the hybrids produced unless they partook of the nature of the type for which I was searching. The present application is for so a hybrid of which the male parent was P. niara plantierensis and the female parent P. charko- The method which I have employed in producing the seedlings of the hybrid poplar set forth 66 clusters of flowers on the female trees before the fiowers had opened in order to prevent normal pollination. Later, pollen was obtained when the flowers had opened, from the flowers of the selected male tree. The pollen was taken at once to the female tree and, by means of awad of cotton, dusted over the femalefiowers. The sacks were immediately g-r'eplaced .ftoj fprevent{ normal pollina tion. After about' two weeks the 'paper'sacks were replaced by green cheesecloth sacks.

Approximately six weeks later when the seeds had ripened, they were removed, the cottonearefully. picked off and the seed planted in damp sand.' When the seeds had germinated-and the little trees had reached a, height .ofabout ,two.

inches, the small trees wer*e-transferredto larger containers and separated somewhat. Later, the

seedlings were individually planted. ,At the end of the following summer the seedlings of desired characteristics were selected -.for propagation,

- I havefound that;bysimply taking-the cuttin s, a ds a gaa m l ran m m .e zht inchesin depth in damp ground; by means of a sharp stick, putting thelower end of a;.cutting,% inch in diameter-and twelve or fourteen inches in -length .in thehole, and pressing the ground back, around; the ;:cu tting.-.fully 95 per cent. of-the cuttings of,.the new,:hybrlds will grow.--- Asis known'to :those;skilled-in the, art, this vitality: is.

not-gshown 1 by:.;t e

in parents. ;,Indeed, in the case ofthe common-poplar (P; tremuloides) for ex ample; not-more than :0218102'. two in a thousandwill grow under the same circumstances. -.The general method of-propagation applicable to, the new, hybrid poplar constituting the present invention; is asfollows: From; the;;seedling tree produced,cuttings of .thenew wood (the preceding summer's growth or the growth of 'two summers);

are made after the leaves have fallen in the fall. These cuttings may betaken, generally speaking. duringtheperiodifromNovember to March. The cutting from ;;the small-tree then divided ,into pieces approximately from ten to fifteen inches in length, These cuttings are; stored in an ice houseor similar cool room or placed under ground until the-time for-planting is at hand. Of course; they mustnotbe allowed to dryout. The cuttings may be planted either in thefall' before the ground-has become frozen or, as is preferable, in the spring shortly after .the frost has left 'the ground and before the weeds have started to grow vigorously. The cutting is inserted in the ground,

where it will begin to grow with considerable rapidity. I have found that, in the latitude of New York, with average summer weather, the cutting of this newvariety will grow into a tree about six feet in height by the 15th of September. Under the same circumstances, the pure species which were the parents'of this same hybrid will not reach aheight of more than two or three feet. The growth of this new hybrid poplar in succeeding years is about the same as during the first year, that is, a gain of about six feet in height and approximately an inch in diameter per year may be counted on. 1

- I have found that from one cutting there will be obtainedin one summer a five to seven foot tree. By cutting this tree into cuttings of say fourteen inches in length, there may be obtained from six to ten cuttings suitable for planting the following year, and from the old stalk there will come up a number of shoots so that during the following year there will be obtained not only the six to ten cuttings (each capable or providing "i effects of 'evi dent that- ,cm. long. ,"mey 1111,18.v I5

. B55 AVAlLABLE COPY six-to ten new cuttingsforpropagationlbut from the original stall: sufilcientmat'erial to furnish another fifteen to twenty cuttings.

as will be apparent, if the tree is not cut up it will grow to be a mature tree and can be expected to increase in diameter nearly an inch per year per year. The exact e the particular iniuuestionf' lay the length of the 'ly" irijduring that the new hybrid poplar above referred to e thrives on sunshine and rain but requires little in the way of rich soil or fertilizers. Analyses of tli'e'w'ood show that this hybrid poplar, contrary to most-treesi doesnotrtake upirom the soil mueh more ,.than.;a ;trace of nitrogen, potash or phosphates. In'ff tljattempts to secure the usual g fertilizer have failed to show more than v V about 10 per cent.'increase in growth due to fertilizer treatment. In no event 'has the rate of increased 20 cent. by the'use'of fertilizer.

. While thejabove describes the-method always I 20 Q growth of;the herein describedhybridepoplarbeen i the treeexcept ,theleaves can be used for propagation andgthusia much morejrapid multiplication f a le t w .be.-provided.;,.1....,.-.

Of th e hybrid :1 poplarsw-kn, A

P, seamen?! enerally-considered. v ;the most ap aa owi s m s ti ows annmlzrinssioiffonly about $6 :inch'. -,-.-Thewild"poplars. such;as P. 'tr 'mu idaar, wh hrare; nqwcustomarily. u ed for lumber and pulpwood purposes-show'anannual ringofabout-illidnchflilt issaccordingly.

a surpr s n .M OtzBj-OWQ insthat-Jt is much more rapid, in growing than the pure species, ordinary aspen,-, P. tremuloides, which is con.- sldered the fastest growingcommercial wood of the northern ,='forests,;or,: the hybrld poplar grown in lumber plantations in-";='Italy; and zgrrance; P. euaenei, which is considered thesfasteshgrowing of the hybrid poplars-hitherto known.

'rne buds are obtuse fto laneeolate,

1 .0 light thenewhybrid described sometimes flattened, lenticellate, and 3.5 to 3.! 5

cm. long. The stipules are'triangular, acuminate,

light green with brown tips, andfugacious.

The young leaves are deltoid; broadly cuneate at the base, with tips mucronate. The blades are pa-leyellow-green, glabrous, and the petioles are green to reddish sparsely pubescent. The leaf margins are finely crenate with 7 to 10 crenatlons per centimeter. The blades are1.2 to 1.5 cm.

wide by-i.5 to 2.2 cm. long. The veins are bright green and the petioles measure 1.3 to 1.8 cm. long.

The infantile leaves are shown in Figure 1 of the original drawing in exact size. In color they are dark yellow-green, which is unexpectedjin such smallleaves. The mature leaf is shownin full size in Fig. 2 of the original drawing.

. Stems The older stems are round, rugose, becoming somewhat ridged toward tips, very sparsely pubescent, becoming glabrous toward the tips. The older stems are pale grayish green while the younger are light brown to reddish brown. The lenticels are white, oval toward the base, measuring 1.3 to 1.6 by 1.2 to 2.5 mm., and gray, linear toward tip, measuring 0.4 to 0.6 mm. long.

' Leaf scars The leaf scarsare somewhat triangular, de-- current, keeled by ridges, and show three bundle SCSI'S.

Wood

Resistance to disease This new hybrid poplar is not affected by the [common poplar diseases. Eor example, it seems ito be entirely immune to Cytospora, the most common disease of both the wild and cultivated ora medusae, the red rustthat has proven to be at pest to most poplars growing in America, 1. e. those designated under the names of P. tremulowee, orandidentata, anaulata, balsamilera, deltoides, wislizeni, occidentalis. dilatata. and W cans. European poplars are similarly affected. One would like to have available the flower and characteristics but obviously theycan not be ven as it would require a tree to years "old to get these characters in true form. It was felt that it was not safe to attempt to get flowers d seed growth by grafting on mature trees as such growth is often affected by the hormones present in the sap of the grafted tree. A study of the root producing hormones along zhe lines of the work done by Wend brings out that this hybrid produces an exceptional amount If such hormones.

The new hybrid poplar which I have developed :hows not only a more rapid rate of growth than he parent trees but a greater freedom from the nrdinary diseases to which poplars are susceptiile. In addition, this hybrid poplar shows an 'ncreased length of fiber as compared with that If the parent trees. As is obvious, this greater ength of fiber is important, not only because t provides a wood of greater 1 mechanical trength, but even more 'so because it provides a rood which when used for the making of paper 3 found to give materially stronger paper. As

Eoplars. It is likewise not affected by Melampis well known, greater length of fiber is a decided advantage from the paper making standpoint. The ordinary popular used for paper making, known as P. tremuloides, has in the case of a one year old plant, sampled a foot from the ground, a fiber length averaging about 0.54 mm. whereas the new hybrid set forth above has fiber length under the same conditions of about 0.70 mm. These figures are for small trees in a single summer's growth and are obtained from a series of 500 measurements for each individual. The new hybrid covered by this application showed in this series of measurements a maximum fiber length. of 0.98 mm., 9.

- minimum fiber length of 0.55 mm., and an average flber length of 0.695 mm. The standard deviation was 0.06819. .Measurements made in the same way on P. tremuloides. a common pulpwood tree, showed a maximum fiber length of 0.74 mm., a minimum fiber length of 0.39 mm., and an average'fiber length of 0.544 mm., while the standard deviation was 0.07011. Older trees of the new hybrid poplar have acorrespondingly longer length fiber; that is, the same approximate ratiosare kept up.

The characteristics of this hybrid are:- (1) Fiber length of about 0.70 mm. in first years'growth. 1

1(2) Growth not increased 20% by fertilizer. (3) Rapid growth in diameter, e. 8. inch ring width.

4) Rapid growth'in height, e. g. about 6 feet in a year.

(5) Large proportion of the wood in the bole. (6) Few branches. (7) Deeply colored infantile leaves.

(8) Resistance to disease.

(9) Ready propagation from cuttings. (10) Superior size and form. There are scarcely any other characteristics that could be named which, from the viewpoint of those engaged in'the art of growing trees for pulpwood or lumber, could be as distinctive as the major ones of those listed above, 1. e. length of fiber, freedom from disease, speed of growth, and nearly entire lack' of fertilizer eflect.

From the foregoing it will be seen that I have developed from the parents P. nigra plantierensis and P. charkowiensis'a new hybrid poplar which is particularly suitable for supplying wood for lumber and for use in making wood pulp and which, because of the rapid growth rate of the trees and-freedom from disease, is particularly valuable for reforestation purposes.

I claim:

A new and distinct variety of poplar as described characterized particularly by its superior size and form, its dark yellow-green infantile leaves, its average fiber length of about 0.70 mm. in one year old trees, and its resistance to disease.

RALPH H. McKEE.

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