ON BREEDING EXPERIMENTS ON PLANTS. 275 



Incidentally, reports have also been filed describing the condition of the roots of 

 seedlings of the same and other species growing in the nursery attached to the 

 Imperial Institute of Forestry and of material of P. canarienais sent from TenerifiEe by 

 an officer of the Australian Forestry Service. 



(B) An intensive study of a newlj- afforested area has been undertaken by means of 

 field experimental plots supplemented by pot experiments with transported soil. The 

 area selected is on the Wareham plantation of the Forestry Commission, where con- 

 siderable difficulty has been experienced in establishing Pinus sp. from seed. Here, 

 on an area of one-tenth of an acre fenced and surrounded by a fire screen, experimental 

 plots have been sown and subjected to various treatments : e.g. cultivation, applica- 

 tion of manures, and inoculations with humus from various sources. Considerable 

 time and labour have been expended in obtaining what is regarded as suitable samples 

 of humus for soil inoculations, and these experiments have been checked and 

 supplemented by pot cultures. For comparative purpose a series of control plots 

 has been treated similarly at a forestry station in the north of England on peaty 

 soil of a different type from that at Wareham. 



From the nature of the case, these experiments cannot jdeld results capable of 

 interpretation for several years. In the meantime, observations have been made on 

 the reaction of seedlings in pot culture to soil from the Wareham area and data 

 collected bearing on the presence of a factor toxic to vegetation. 



(C) Marked differences are known to exist between geographical races of P. 

 silvestris. Attention having been drawn to this matter by comparative observations 

 on the mycorrhiza of such forms, sowings have been made of seven geographical races 

 of P. silvestris in three different localities. Observations on the mycorrhlza-forming 

 capacities of the resulting plants, may, it is thought, provide data throwing light on 

 the determining influence of soil conditions on mycori'hiza formation in general. ■ 



One conclusion of a positive kind ma}- be already placed on record. It is clear 

 that certain exotic Pines, e.g. P. laricio and P. pinaster, find in this countr}' fungi 

 capable of forming mj-corrhizal associations of a favourable type. Whether these are 

 identical with those formed bj' the trees in their native habitats or are representative 

 of all the structural types formed under these conditions has yet to be learned. 



The present report offers an opportunity to acknowledge the unfailing help and 

 co-operation received from officers of the Forestry Commission in this country and 

 from the Director of Forestry in the Irish Free State, without which this work could 

 not profitably be undertaken. 



Experiments with transported soil have been rendered possible by the exceptional 

 facilities possessed by the Department of Botany, Bedford College, University of 

 London, without which such work would be impossible in London. Acknowledgment 

 for the use of these facilities is due to the Council and Principal and to the Head of 

 the Department of Botany. 



For the prosecution of these researches, funds are required : — 



(a) To carry on the work already undertaken and extend its scope. 



(b) To provide a small shelter house of a type different from the ordinarj' 

 greenhouse and more suitable for growing pot cultures of Conifers on a larger scale. 



(c) To cover expenses relating to the collection of data respecting the tj'pes of 

 mycorrhiza formed by various exotic species of Pinus in their native habitats and 

 thus provide the nucleus of a tj-pe collection for purposes of reference. 



Breeding Experiments on Plants. — Report of Committee (Sir Daniel 

 Hall, K.C.B., F.R.S., Chairman; Mr. E. M. Marsden-Jones, 

 Secretary ; Dr. K. B. Blackburn, Prof. R. R. Gates, Dr. W. B. 

 TuRRiLL, Mr. A. J. Wilmott) appointed to carry out breeding experi- 

 ments as part of an intensive study of certain species of the British Flora. 



Research aided by the grant of £50 made at the 1928 meeting of the Association, 

 permission to use the unexpended balance of £32 2s. 6d. having been granted at the 

 1929 meeting. 



This report is a continuation of that published in the Report of the Brit. Assoc. 

 1929, p. 267. 



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