experiments were carried on with a steer to study the available energy of timothy hay." On the basis of theoretical considerations the authors came to the conclusion that for cattle a maintenance ration is a question of tissue replacement rather than of heat production, and, therefore, that the value of a given feeding stuff for maintenance depends upon the availability of its energy. For instance, it is at least very probable that the work of digestion and assimilation in the case of a material like corn meal would be materially less than in the case of hay; or, in other words, that a larger percentage of the energy of the grain would be available for the maintenance of tissue. It would follow from this that in case of a ration consisting largely of grain, a less amount of material or of metabolizable energy would be required for maintenance than in the case of a ration consisting exclusively of coarse fodder. In other words, the maintenance ration is a variable rather than a constant, depending upon the kind of food used. In the experiments reported the maintenance requirement of the steer, as computed, was 10,710 calories, the average weight of the animal during the experiment being approximately 410 kilograms. On the assumption that the maintenance requirement is proportional to the two-thirds power of the live weight, this equals 12,197 calories per 500 kilograms live weight. An important feature of the experiments is the information they afford regarding the substituting value of nutrients. This and other theoretical questions connected with the metabolism of matter and energy are discussed at length. a U. S. Dept. Agr., Bureau of Animal Industry Bul. 51. EXPERIMENT STATION WORK WITH APPLES. By C. B. SMITH, Horticultural Editor, Office of Experiment Stations. Farm problems are not solved in a day. Often they are not alike two years in succession or in two contiguous localities. But they come up with each recurring season and the experiment stations are asked to solve them. The stations, located under widely varying climatic and soil conditions, undertake their solution. From time to time bulletins and reports are published showing the results obtained. These may cover but one phase of the subject as studied at one or more stations. Other stations in other States may be called upon to study different phases of the same problem. Thus data accumulate. A single bulletin may show but little progress. If one read that alone, it might seem that the advance in agricultural knowledge was slow and fragmentary. It is not, however, by considering the individual results secured at one station in one year that the amount of work accomplished or the present status of a farm problem can be ascertained, but by study of the combined results secured at all the stations for a series of years. When all the results secured over a long period of time at all the stations are brought together, it is often surprising to find how large a number of problems have been worked out. This is especially true of all our more common field crops and orchard fruits. To illustrate this and to show just what the nature of the work is that has been done and the advance that has been attained in a particular line, it is proposed to assemble the results thus far secured at the stations with the one crop apples. No fruit is so largely grown in America as the apple. The number of apple trees and the yield of apples in bushels far exceeds that of all other fruits combined, including citrus fruits and grapes. It is not strange, therefore, that since the establishment of the agricultural experiment stations throughout the country more than 170 bulletins. and reports should have been issued on the culture of apples. A large number of these publications report the results of experimental work to show the effects in orchards of clean cultivation, sod, cover crops, fertilizers, root pruning at transplanting, different-length root grafts, crossing, girdling, thinning, harvesting, storing, cold storage, composition, utilization, and other problems. It is work along these lines that has been reviewed in this article. The work with varieties and in spraying, and studies of the diseases and insects affecting apples, have been omitted. So much has been done along these lines that, if properly reviewed, it would fill a volume. Attention in this article has therefore been centered on the other questions relating to apple growing which have been investigated by the stations. a PERIOD OF GROWTH. In investigating the growth of the branches of apple trees the Wisconsin Station found that active branch growth ceased one year June 4, while the following year it continued on many trees until October 1. Cultivation or late rain and favorable weather may induce trees to make a second growth, commencing the middle of July or later. One instance is cited where, out of 325 trees that had made a second growth, 66 per cent were in cultivated ground and 21.1 per cent in sod. On the cultivated soil the branch growth on many trees was as much asone-half inch per day. Many apple grafts, top-worked, continued to grow several weeks later than the stocks. The bark was set on many of the smaller branches by August 15, while on the larger trunks it could still be peeled at that date. Another season the bark slipped readily on all branches up to September 15, and on the larger branches to September 25. Root growth was found active one season as late as October 6, although no growth of twigs had occurred on any of the trees later than July 1. In Tennessee the experiment station found that, as a general rule, apple shoots make their principal growth in length before July 1 and that the outermost shoots finish their growth in length sooner than the lower shoots. An examination of the growth of buds on the various trees showed that 50 per cent of all the buds found on Jonathan in 1900 above the lowest limb started into growth by June 30, 1901, and 15 per cent had made shoots three-fourths inch long or more. With York Imperial 60 per cent had started into growth and 28 per cent made shoots. APPLE BUDS AND POLLEN. An extended study has been made by the Wisconsin Station of the development of apple buds and the germination of apple pollen. It was found that leaf buds and flower buds are not structurally distinct. Every bud on the apple tree is formed as a leaf bud and every bud on the tree has the power to become a flower bud. Leaf and flower buds are, in a measure, interchangeable. By pruning away the branch immediately above a flower bud it may be converted into a leaf bud, a Wisconsin Sta. Rpt. 1900, p. 3. and by ringing a branch just below a leaf bud it may be converted into a flower bud. Factors which tend to the formation of flower buds are any restriction of prepared food in the branches, such as is caused by ringing or a wrinkling of the bark formed by the union of the fruit spur with the branch which supports it. Dry weather is also conducive to the formation of flower buds, since during such dry periods evaporation through the leaves is rapid and sap becomes concentrated and rich in prepared food. Flower buds are then formed in portions of the tree where there may be no restrictions to the movement of the sap, as at the end of young shoots. Whenever the water supply is increased the tendency is to wood growth and the formation of leaf buds. A decrease in water supply tends to make flower buds. A normal growth is accompanied by normal formation of flowers. When the fruit spurs of a healthy tree push into growth or sap sprouts start freely from the old wood, growth is abnormal and fruit production is postponed." The first clear evidence of flower buds on the apple tree was found one season June 30. Another season flower buds for the most part were formed between August 1 and September 3. Flower buds do not usually form until active wood growth for the season stops. At that time they may begin and continue until cold weather sets in. The same fruit spur has been found to fruit annually in some instances, instead of biennially, as has sometimes been claimed. In the flower buds the calyx and receptacle are first to appear, next the stamens and petals, which are apparently outgrowths of the calyx or receptacle, and finally the pistils, which are extremely slow in developing. The observations indicate that flower buds seldom or never revert to leaf buds, though they may not develop into flowers for several seasons. If heavily shaded they may never bloom; but during very favorable seasons for the formation of flowers all the 1-year old, 2-year old, and 3-year old flower buds, many older buds, and some buds formed during the year, may form embryo flowers. This explains why an excessive fruit crop is always followed by a scanty one. "There are no reserve buds. Only the buds formed the preceding season are developed, and the draft on the tree necessary to develop so many apples prevents many of these from forming flowers, even if they are of the annual flowering variety." While the production of flower buds on the apple tree is largely controlled by climatic conditions, a number of other factors also enter in over which the orchardist has control. The temperature may be modified by planting on the north or northeastern slopes. Early a Amer. Gard., 22 (1901), No. 332, p. 330. b Wisconsin Sta. Rpt. 1899, p. 289. e Wisconsin Sta. Rpt. 1901, p. 304. spring plowing and frequent shallow cultivation will preserve a good supply of moisture in the soil, which is so essential to the growth of healthy leaves and buds. In seasons of excessive rainfall the ground may be left uncultivated to hasten evaporation. In the Northern States it is desirable for the formation of flower buds that wood growth come to an end about July 1. Should growth continue after this date it may be checked by moderate root pruning. This can be accomplished by plowing a furrow down the rows each way, followed by a subsoiler, so that the small roots on each tree can be cut off. Plowing should be followed by a cover crop to evaporate any excess moisture in the soil. a At the Rhode Island Station a study was made of the effect of light on bud development. An examination was made of the number of flower buds on limbs exposed to sunlight as compared with those on limbs partially shaded. The proportion found was 182 clusters on limbs in sunlight and only 136 on limbs partially shaded. This suggests the desirability of thinning out the tops of trees that become too luxuriant in wood and leaf growth, so that more flower buds may be produced. The Canada Experimental Farms' report some experiments in which whitewash covering the trees appeared to have but little effect in retarding the swelling of apple buds in the spring. Mulching apples with strawy manure in winter when the ground was deeply frozen and covered with 8 to 12 inches of snow did not retard leafing and blossoming the following spring. Some of the conditions controlling the germination of apple pollen have been studied and reported upon by the Wisconsin Station. In a saturated atmosphere under a bell jar apple anthers failed to burst after fifty-six hours, while in dry air the anthers on duplicate twigs had practically all burst. The experiment is believed to indicate that during periods of protracted rain, or as long as the trees are wet with rain or dew or enveloped in fog, practically no anthers burst and therefore no pollen is wasted. The anthers were not found to swell perceptibly until the maximum temperature reached 70° F. Other laboratory experiments with blossoms indicate that pollen is discharged freely only in warm and dry weather. At a temperature of 40° to 51° F. pollen germination was very feeble, a fact which indicates that the vitality of the pollen is not likely to be injured by exposure to a prolonged rainy period if the weather remains cool. If it rises to 65° or 70° F. the vitality of the pollen may be destroyed. Observations at the New Jersey stations showed that no apples set when the fruit blossoms were not permitted to get dry during the period of pollination. a Rhode Island Sta. Bul. 37. b Canada Expt. Farms Rpts. 1899, p. 94. e Wisconsin Sta. Rpt. 1901, p. 289. |