BUD VARIATION IN THE LISBON LEMON. 6 



VARIABILITY WITHIN THE VARIETY. 



The systematic studies of the variations of the California citrus 

 varieties were begun with the Washington Navel orange in 1909. 

 Later, investigations were commenced with the Marsh grapefruit 

 and Valencia orange. In June, 1911, the study of variations within 

 the Eureka lemon variety was begun. This variety was found to be 

 subject to variability in about the same degree as the citrus varieties 

 previously studied.^ 



One year after beginning the study of the Eureka lemon, tree- 

 census studies were begun with the Lisbon variety. It was found 

 that this variety was subject to variability m about the same degree 

 as the Eureka. In order to secure defmite information on this sub- 

 ject individual- tree performance records were begim on a plat of 

 trees of the Lisbon variety in June, 1913, included in which were 

 typical trees of all the important strains discovered up to that time. 

 In these studies detailed performance records have been obtained 

 covering a total of 128 Lisbon lemon trees. The individual trees in 

 these plats have been picked monthly as far as possible. As with the 

 Eureka lemon studies, the frequent pickings during a period of several 

 consecutive years have resulted in the accumulation of a very large 

 mass of data and information, from which conclusions have been 

 drawn as to strain and individual- tree characteristics. 



In addition to these detailed studies, cooperative individual-tree 

 performance records have been carried on in several California lemon 

 orchards during this period with about 13,000 trees of the Lisbon 

 variety. 



The variability of the Lisbon lemon described in the discussion of 

 the results of these studies must be clearly distinguished from the 

 fluctuating variability due to climatic, soil, cultural, or other environ- 

 mental influences. The variations considered in these studies are 

 those which have been found to be transmitted by budding and are 

 inherent variations. The fluctuating variations, such as modifica- 

 tion of the size of the fruits, slight differences in the color of the 

 leaves or fruits, or similar changes due to climatic conditions, cul- 

 tural factors, or other causes, have not been taken into account 

 except as indicating the effect of certam environmental factors in 

 tree and fruit development. All of the variations considered in 

 these studies have been traced to individual fruit or limb varia- 

 tions in trees growing imder normal conditions. 



OBJECTS OF THE INVESTIGATIONS. 



The objects of these mvestigations have been to determine the 

 frequency and importance of bud variation in the Lisbon variety of 

 lemon; to ascertam the relative value for commercial orcharding of 



1 See U. S. Dept. of Agriculture Bui. 813, entitled " Citrus-Fruit Improvement: A Study of Bud Varia- 

 tion in the Eureka Lemon." 



