ROOT DEVELOPMENT IN PLANTS.

North Otago Times, Volume XXVIII, Issue 2157, 2 April 1879, Page 5 (Supplement)

ROOT DEVELOPMENT IN PLANTS.

All who have paid attention to the subject know that the roots of trees and plants travel an enormous distance in search of food. About this time last year we cut down a large old specimen of Robinia pseudoacocia, and, as its habit of throwing up suckers is well known, I watched with some interest during last summer the constant production of young growths that sprang up from the roots left in the ground, and which extended in some instances to as much as 70 feet from where the trunk hid stood. Cutting aown the tree had removed the usual outlet for the roots' activity, and so had imparted a wonderful stimulus to the crop of suckers, which came up in sufficient numbers to have quickly formed a thicket if left undisturbed. It has beeu said that the roots of plants are rarely ever distributed in the same regular manner as the branches are, and I look upon this as easy of explanation. The functions that are performed by the roots of plants are of a twofold nature : the first is to search for and forward on to the part above ground whatever can be obtained in the way of food ; and the second is to afford, by its grasp of the soil, a firm anchorage. The latter employment is, I think, always subordinated to the first, which is the most important. I could nerer discover that the roots had any particular partiality to any point of the compass, as sometimes the great bulk of the roots were on the north side of the trees, at others they had travelled southward* ; and the conclusion I have come to is that, like human beings, they naturally gravitate to where the food is most plentiful and most easily obtained. Id some cases, too, there are obstructions in the way, of a character to induce or compel an alteration in their course. The same causes have the same effects upon the branches of the tree, for those on the outside of a plantation always grow most on the outward side ; and it is very common, in very windy districts at the seaside, to tee the greatest development of branches opposite to the direction from which the wind blows.

I hire no doubt, if the character of the •oil were the tame on all aided of the tree, that the root development would be pretty equally balanced, in the same manner as the branches of a tree usually are when standing singly In a field. The proportion the roots bear to the branches has been variously estimated at from 20 to 50 per cent ; hut as regards trees or plant* growing in a state of nature, it is next to impossible to draw a correct conclusion. This, therefore, must in the main be the merest guesswork, though no doubt it raries greatly in different species, and at different ages of the tame species. But there is one thing, I think, that never varies, and that is the balance or reciprocity between the parts under ground and above. The fate of the two is so intimately connected and bound up together, that one cannot extend itself without communicating its impulse to the other. A strong development of wood and foliage cannot be built up on a weak foundation, and neither can a weakly, starveling plant emit strong roots. At regards cultirated plants, I think root development is mainly a question of preparation of the soil. The distribution of the manure in small particles throughout the soil leads to the diffusion of the roots, and always, when digging in manure, the large pieces should be well broken up. In rich, moist land the scattering of the roots in search of their food may be less important, as sufficient moisture may be present at all seasons to supply their needs. But in dry, porous soil, if the roots are huddled together or only occupy a limited space, when the pinch comes the shock will be all the more severely felt in consequence of the manure being placed on the land carelessly. I think, under all circumstances, the deeper the land, and the more the manure is disseminated through it, the better will the crop go through hardships of any kind, and the more profitable will its produce be ; but depth or bulk of soil is of no particular advantage to a plant unless it takes possession of it with its roots during some period of its career ; and to this end, when manure is given, its regularand perfect distribution is a matter of some importance. Water is a prime necessity to plant growth, and a thorough scattering of the roots, induced or stimulated by the diffusion of the manure, places them in a position to draw their supplies from a large area, and consequently such plants suffer less from drought or any other casualty thtt may come upon them. In growing such crops as cauliflowers, peas, and celery in trenches, a better result is obtained by thoroughly incorporating the manure with the soil to a considerable depth, than leaving it in a body and planting the crop just over it, or, in some cases, almost inserting the roots of the plants in the manure.