Vol. XII. Xo. 291. 



THE AGRICULTUKAL NEWS 



lOI 



PROBLEMS lU PROPAGATION BY 

 CUTTINGS. 



In continuation of this abstract of Professor Baylpy 

 Bulfcur's recent lecture (published ii: the Journal of the 

 Jioi/'i! llnrliiullin-al Soci-tii for March 1913) reference may 

 be made to some interesting allusions tQ problems of vegeta- 

 tive propagation offere<l by monocntyledonous plants. Most 

 jiLople are disposed To think that monocotyls do not propa- 

 gate by cuttings. To dispel this idea the lecturer proceeded 

 to describe the developtnent of an Asparagus cutting: the 

 idea-S involved, however, can he more aptly illustrated to 

 suit tropical conditions by referring to the propagation of the 

 sugar cane. 'i"he germination of the cuttings of thi.- plant 

 were very fully described in a recent issue of the Ai/riciil 

 tiiriil News (Vol. \U, pp- 158 and 159) and the principle of 

 development may bo summed uji by saying that growth 

 consists first in the enlargement of a lateral bud and the 

 formation underneath it of a new stem from which 

 arise adventitious roots. It should be pointed out, how- 

 ever, that in the sugar-cane cutting, root development occurs 

 first at the nodal zone to supply the preliminary moisture 

 required to set bud development in action. The essential 

 feature is that a new plant is produced from each bud, which 

 is (juickly separated from the cutting by a layer of cork Its 

 connexion with the original stock is severed. From the 

 beginning, the monocotyledon di.splays lateral growth; from 

 the beginning, the dicotyledon has the instinct of terminal 

 t?rowth, which is always more rapid than lateral development. 

 The terminal shoot of the dicotyledon extends as the new 

 plant from the rooted cutting. A lateral bud develops aa 

 the new rooted plant in the monocotyli'don and the terminal 

 portion of the cutting dies. 



The next important point dealt with in the lecture 

 was propagation by root cuttings. In the term, 'root 

 cutting', the true root is referred to. It is pointed out 

 that this is governed by the same conditions that regulate 

 propagation by stem cuttings. t)ne thing, however, is differ- 

 ent. 'I'he tendency for roots tn produce adventitious buds 

 is not as stmng a.s the tendency "f stems to produce 

 adventitious roots The cut surface of the dicotyledonous 

 root cutting generally forms callus as in the stem cutting, 

 and in this callus the shoot buds will be produced. If not, 

 the laids may develop from the pericycle from which t-be 

 daughter roots also arise. It is noted that comparative 

 experimental work with root cuttings has not been extensive 

 and that there is much to learn in regard to the stimuli 

 conducing to shoot formation from roots. 



Turning from the subject of roots, attention was given 

 next to propagation by leaves. After referring to Bryo- 

 phyllum, and to the function of the swollen lenf in a fily 

 bulb, the lecturer goes on to say: 'given the possession of 

 adequacy of active indifferent cells, that is to say, cells 

 not already impressed with a definite morphological 

 destiny, and of a sufficiency of food, ttien in proper 

 conditions of moisture, aeration, and temperature, any 

 leaf may be used as a cutting. Nor is the whole 

 leaf necessary — petiole alone, or lamina aloae, or portions 



even of these may serve The practice of 



using leaf-cuttings was more commonly employed in the past 

 that it is now; propagation of citron, lemon, and laurel by 

 this method is of great antiquity. Nowadays, however, it is 

 restricted Iiy gardeners to a comparatively small number of 

 facile forms— such, for example, as one finds in KegODia, 

 Melastomaceae, Gesneraceae, C'rassulaceae, where there is 

 substance and abundant water in the leaf — soft leaved plants 

 one may cnll them.' 



In continuation, it would appear that the chief difficulty- 

 which accompanies leaf-propagation is the slowness witb 

 which, not the roots, but the bud shoots form. This is seen,. 

 for example, in Ficus claslint, Camellia, and I/oi/a (tirnosa. 

 The paring of callus does not overcome the difficulty as it 

 does in the case of root formation from dicotyledonous stem- 

 cuttings, and it would appear that the subject is deserving of 

 continued investigation. There is evidence to show ihat 

 the quality of the food material in the leaf affects shoot 

 development. 



Turning from these matters to the final subject in the 

 lecture, namely the environmental conditions necessary for the 

 quick 'striking' of cuttings, it was pointed out that the chief 

 external stimuli are air, heat and water. Air is often over- 

 looked and the old canon should always be borne in mind, 

 'that the sunk end of the cutting should go no deeper tlian is. 

 sutiicient to maintain it steady in the soil.' 



Proceeding with the subject, attention is given to the arti- 

 ficial methods adopted to ensure quick vegetative development 

 experimentally at the Royal Botanic Gaidens, Edinlmrgh 



The two outstanding lines of practice there may be 

 termed: (1) under root watering in shade; (2) overhead 

 watering in sunshine The chief feature of (1) is that the 

 soil for cuttings overlies a chamber containing water from 

 which the soil is separated by a layer of air. The water 

 can be heated to a required degree by the water of the- 

 heating system circulating in the li inch pipe at the bottom 

 of the tank, and the moisture rising from the surface of the 

 heated water ascends through a sparred frame and passe.'t 

 upwards through the overlying soil. In this way the soil 

 is kept moist, and any required temperature can be main- 

 tained by regulation of the valve. It is believed that the- 

 temperature condition is of paramount importance. 



The above method is particularly adapted to plants with 

 hairy and woolly surfaces. It eliminates the risk of surface- 

 decay that attends overhead watering in such plants. 



The second practice, that of overhead watering in the sun, 

 is believed to have been borrowed originally from the French. 

 The method adopted at Edinburgh is as follows. The 

 cuttings are plunged in sand in an ordinary frame exposed 

 to full sunshine and watered at short intervals, say every 

 half hour. The watering may be done automatically or by 

 hand, but the latter involves frequent opening of the frame. 

 The soil temperature may rise to an intense degree, but 

 rtuctuates. Some plants under this treatment 'strike' much 

 more rapidly than under the first system. 



In conclusion, the lecturer drew attention to the- 

 possible im|iortance of direct sunlight as a factor (irreajiec- 

 tive of heat unit) in the germination of cuttings, and finally 

 emphasized the paramount importance of soil temperature in 

 any considerations concerning the interesting and econom- 

 ically invaluable practices involved in the subject of his^ 

 lecture. 



The results obtained at the Agricultural Experiment 

 Station, St. Croi.x, with seedling canes raised in that island, 

 are de.scribed in the St. Croix Aris for April 23, 1913. The- 

 first table of figures shows the rcsubs obtained during 1911. 

 The list is heade.l by S.C. 1-2-] which yielded 5,5880). of 

 sucrose per acre. The resulti of the second year seedlings 

 are interesting in view of the fact thit S.C. l'_'-l 1, which was. 

 eleventh in the first year, retained its high position and gave 

 cane at the rate of 2(> 8 tons per acre during ten months of 

 growth in a dry )ear. The juice of this cane was found to- 

 be very rich and pure. In the .second year it was found that 

 S.C. 12-GO, which was last out of sixty in 1911, rose fron^ 

 this place to thirteenth in 1913. 



