PLANTS AS PUPILS

Evening Post, Volume CVI, Issue 46, 1 September 1928, Page 7

PLANTS AS PUPILS

«. BIOLOGY'S VICTORIES EDUCATING A RUBBER SHRUB EIVAL TO HEVEA "At this juncture the management lad acquired small lots of seeds of less than a dozen varieties of the shrub (the seeds of which could bo used to giow plants with a higher percentage of rubber than the wild plants) and gome pretty definite knowledge of a practicable m-atb-i of growing crops of the improved -varieties. This, with : some, clear ideas as to the soil conditions and climate best suited for guayule, represented tho results of fourteen years' work." Tho above passage is taken from a ' '"Scientific American" article on the cultivation of a Mexican-Texan wild "plant (of many varieties) by American plant-biologists, who, it is claimed, have so improved the rubber-yield of this guayule plant (pronounced 'wyoolo') that the United States (which uses 66 per cent, of the world's rubber production) will no longer be dependent upon the rubber now obtained from the hevea tree of the Tropics. The writer of the article (Dr. D. T. MacDougal, plantbiologist, Carnegie Institution) does not consider it to be either likely or deBirable that guayule will put hevea out of business. He implies that a United States market for Americancrown guayule is consistent with a world-market for Far Eastern rubber, and he states that limits of manpower rather than of rubber-demand are likely to retard further development of tho hevea industry in Malaya, "where 750,000 coolies are already employed," and where the labour supply is not (as has been thought) inexhaustible. NEW ZEALAND'S SPECIAL INTEREST. Tho "Scientific American" article presents features that are interesting from two points of view. Firstly, in a general way the whole world is vitally •interested in the expanding uses (and sympathetically expanding production) of rubber, which is a plant of political as well as economic significance. Second, in a'more particular way New Zealand is interested in the attempt to cultivate wild phormium tenax (New Zealand flax), and science's^ great adventures in phormium aud in guayule sefln to be not without parallels and points of comparative value. ■ When the economic investigators took im phormium, they were surpised to find the number of different varieties, or apparent varieties, or at least variations. Concerning guayule, the "Scientific American" article indicates that there are over a thousand varieties ot the wild plant. Whether it be guayule or phormium, the aim of plant-breeding is in any case to obtain that higher rei turn- of the commercial product (rubber in the one case, fibre in the other) mentioned in the opening quotation. This means, of course, that botany ana plant biology and their various researches have long ceased to be something in the air, and have come down to earth in every sense, and are already destined to supply tho fundamentals of great economic developments in which no progressive and competitive "country can afford to be behindhand. Now Zealand possesses a unique flora, -which possibly has more secrets (and more important secrets) awaiting discovery than has the indigenous forest of any other country. Consequently much moro than an academic interest attaches to Dr. Cockayne's investigations into beech, including his discovery of that tree's varieties and peculiar hybrids. It is a matter of gratification that tho Government has developed some sense of the value of brains like those of Dr. Cockayne, and has also sot on foot an investigation into phormium from the biological and plant-build-ing point of view. PHORMIUM, BEECH, TAWA. ■Meanwhile, the story of guayulo as told by Dr. MacDougal is doubly valu- . able if it provides encouragement to those who would win from phormium more and better fibre (possibly a textile fibre), and who would develop the latent riches of beech (the Cinderella of the forest), and who would make a profitable pulp and paper use of our neglected tawa. To attain a competitive level with hevea rubber is not easy. Thousands of species of trees and plants '|show some caoutchouc in their milky juices lor in the thin-walled cells of the wood." So, also, thousands of species contain fibres. But to make a plant yield commercial rubber or commercial fibre, and to. make that plant improve its product in quantity and quality, is generally a colossal undertaking, involving a whole series of achievements in plantbreeding and selection, planting and cropping, manufacturing technique, end machinery processes. If any New Zealand investigator Bhonld feel discouraged, let him again read tho opening passage, and see how far tho guayule investigators (according to Dr. MacDougal) had advanced bo far as cultivation is concerned in fourteen long years. But the fourteen years applies only to the cultivation effort. Prior to that, ' the wild plant had been used commercially. Dr. MaeDougal states that the company concerned (or its allied interests) "has been engaged in the extraction of gum from dried shrubs of the guayule plant collected chiefly from its extensive holdings in Northern Mexico for twenty-two years. Its output has run as high as ten million pounds of rubber monthly." Why, then, did it not go on produc- * ing rubber from tho wild plant? The answer seems to bo that so much wild plant had to bo crushed (the rubber is extracted by a crushing process, followed by treatment in revolving mills, with ■water, the plant having first been torn up by the roots and crushed whole) that tho wild stocks proved insufficient, and therefore a plant richer in yield of rubber had to be produced by selection and breeding. - CULTURAL EFFORT BECAME COMPULSORY. ____ This turn of the tide "illustrates the history of all wild plants utilised m wild plant into cultivation. . . . Tho peak of tho manufacture of material was shortly followed by decimation of the stand of wild plants. It is estimated that the "forest of guayule," which covers about 130,000 square miles in Mexico and Southern Texas, could not be managed to yield more than oOUO tons of rubber annually. When it became evident that attempts at a greater production from wild plants would mean a dwindling industry, & serious scheme for research and experimentation was undertaken to bring the wild plant into cultivation. . . • The technical problems pertaining to the harvesting and germination of seed; the selection, from the vast number of recognisable varieties, of tho half-dozen which might be most profitably grown in fields; and the determination of the hundreds of details of practice, which make for success or failure •of any crop, wore studied." And this was the study, which covered

fourteen years of the life of'a skilled plant physiologist and his various collaborators. WILD PLANT TAMED IN RECORD TIME. On affirming the success this ''attempt to grow rubber in tho United States on a self-sustaining basis, without Government subsidy or aid, as a sound commercial project," Dr. MacDougal says that the experimenters have brought about "the domestication of a wild plant in sixteen years— without parallel in the history of agnculture —and the production of rubber us a field crop with a cycle of three or four years." The cultivated guayule plant comes into production at four years, and continues to grow and to become a more productive unit for another four years, but this rate ot growth-improvement docs not continue after the ago of ten years. Therefore, if any given crop attains its fourth year at a time when prices are low, or when crushing plant is not available, the plant may with economy be .allowed to stand unharvested for another four years, "during which there will be a sufficient increase of rubber productivity to meet interest and maintenance charges, as would be the case in certain forestry operations. In fact, guayule culture is something like a forestry project of short cycle." And perhaps something similar will yet be said of phormium tenax. The guayule plant is not very tall. At two years of age it is shown by a photograph as being hardly up to the knee of a man standing between _ the rows. "It attains an average weight when dried of ljlb." It requires frost but no irrigation. Its scientific name is Parthenium argentatum. LABOUR-SAVING MACHINES. There is not space to tell much of the mechanical inventions or improvisations that accompany the plant biologist's work, but tho following machines may bo mentioned as being part of the technique and of economic importance: — (1) A specially devised seed harvesting machine that gathers seeds from selected standing shrubs, without injuring the shrub. (The seeds "are subjected to special treatment so that 98 out of every hundred germinate"— a record which gathers of phormium seed may find hard to beat.) (2) A special seeder sows these seeds in tbo nursery. It "runs on wooden tracks and will sow enough seed for a 20-aere field in an hour. Seed for 25 million plants was sown last April." The nursery period is about nine months. (3) A transplanter takes in hand the young plants from the nursery and sets four rows at once. This machine "is much like tho common cabbage and tobacco transplanter used elsewhere. A small plough opens a drill ahead of the men, tho seedling is placed in it, and a following tooPOovors it." (4) Six months after planting of tho young plants, "a modified farm tractor, carrying a cultivator rigidly attached to its front, is used," covering four rows at each trip. Weeding must be done for the first three or • four years. When required to be crushed, tho plant is torn out by the roots. ■ Guayule is being taught to live far from its indigenous home and in varying climatic conditions. By the way, hevea itself has also wandered far. "The rubber plantations of the Far East (Malaya) have come from seeds of hevea collected from trees . on the Upper Amazon half a century ago." And phormium tenax has graced the parks and gardens of Australia and other more distant lands for a period probably quite as long. Will it be the fortuno of this country, or of some ; other, to raise phormium to textile importance?