432 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



in the island, and tlie results of the first season's work were so 

 conclusive that two other groves are now being handled in the same 

 manner. Additional data are being secured regarding the flowering 

 2)criod of the more important honey-producing plants of Porto Rico. 

 When completed these data will be of service in determining the 

 proper procedure for handling bees. 



The chemists continued their studies of the nitrogen economy of 

 cane soils. No important differences were noted in yield as a result 

 of applying nitrogenous fertilizers to the experimental plats aside 

 from a greater tendency on the part of the cane plants to lodge. 

 The sucrose and purity of juice were lowest in canes grown on plats 

 that received ammonium sulphate. A study was begun on the effect 

 of fertilizers on some of the disorders of the rice plant, and evidence 

 w^^s obtained that is believed to indicate that the so-called "straight 

 head " disease of rice is caused by an excessive use of nitrogenous 

 fertilizers on poorly drained or unaerated soils. Analyses are in 

 progress to determine the differences in composition of normal and 

 diseased rice plants. 



Variety testing and selection work with beans is being continued 

 by the horticulturist. Marked differences in adaptability have been 

 noted, and some superior strains have been secured by selection. 

 Some white strains have been developed in crosses with a black bean 

 from Venezuela that are exceedingly promising. These have been 

 carried through several generations, and studies made of the seed 

 of progeny of this cross are said to show that black color is domi- 

 nant over white and glossiness of seed coat over dullness. Extension 

 work with root crojjs is in progress. With sweet potatoes, the vari- 

 ety Key West again showed itself to be the most prolific of the 36 

 varieties under test. The value of stakes upon which yam vines 

 can climb was again demonstrated, staked plants yielding 41 per 

 cent more roots than unstaked vines. Spacing tests with yautias 

 and taro indicate higher production for yautias when spaced 3 by 3 

 feet and taro when planted 3 by 3^ feet apart. The coconut ferti- 

 lizer experiment begun in 1912 is beginning to show definite results. 

 The plats which received salt have yielded four times as many nuts 

 as the check plats. In the coffee fertilizer experiments some very 

 pronounced effects are being shown. The experimental work with 

 vanilla was discontinued on account of a serious root disease. Three 

 commercial vanilla plantings in different parts of the island have 

 been made as a result of the station's work on this crop. 



The plant-breeding work is making satisfactory progress. Ear-to- 

 row plantings of corn have shown yields varying from 33.4 to 51.2 

 bushels per acre. Additional work on the production of suitable 

 table corn is in progress, and Fi and F2 generations of crosses are 

 under observation. A cross between Henderson's sugar corn and a 

 native white field corn has been made, and the F3 generation is now 

 growing. Additional nursery testing of various Porto Rican and 

 introduced rices have resulted in the elimination of many varieties. 

 There are now being tested 42 varieties, 10 of which were found 

 growing in Porto Rico. A larger test is desirable, but irrigation 

 facilities are lacking for larger plats. A test of Honduras rice 

 grown as an upland crop yielded 1,301 pounds per acre. Tests of 

 various cowpeas and soy beans are in progress, and wide variability 



