228 PLANT GROWTH SUBSTANCES 



available at present. In Hawaii especially, NAA is used extensively. 

 Under current commercial practice approximately 25 grams of the 

 sodium salt are applied per acre. This is sprayed on by large ground 

 equipment using spray booms 50 feet long (Fig. i). The cost of the 

 chemical is only about fifty cents an acre at present, while the total 

 cost of treatment is roughly five dollars an acre. Only one treatment is 

 required for flower induction. 



The advantages of forced flower induction in the pineapple industry do 

 not lie exclusively in an extension of the harvest season. The much 

 improved uniformity and regularity of flowering and consequently of 

 fruit production is of equal importance. Prior to the introduction of the 

 practice of forcing by chemical means, the earhest and the latest fruits 

 produced in a field during one season might be months apart. This 

 entailed repeated harvests for one and the same field. At present, with 

 chemical flower induction, the entire field is forced into flower at once, 

 and therefore all fruits are ripe at the same time. Thus the entire crop 

 of one specific field can be harvested with a single operation. Still 

 another advantage of the use of chemical flower-inducing agents is that 

 they increase the yield of the fruit per acre, as a larger percentage of the 

 plants is forced into flower than without treatment. 



Systematic hormone treatments have now made planned harvesting 

 a reality. These treatments are so made that when the harvesting in one 

 field has been completed the crew with its trucks and other machinery 

 moves on to the next. The frantic rush, so characteristic of most perish- 

 able fruit crops, has thereby largely been eliminated. 



Chemical flower induction not only makes it possible to determine the 

 date of the harvest, but also to estimate with reasonable accuracy the 

 tonnage a field will produce. A glance at Figure 3 shows that the more 

 leaves a plant has the larger the fruit it will produce. Since after flower 

 formation has taken place the number of leaves on the plant does not 

 further increase, it is possible, by the use of graphs such as given in 

 Figure 3, to predict at the time flower-inducing treatments are made the 

 average weight of the fruit that wifl be produced. Even though much 

 remains to be desired one may say that for the pineapple, crop control 

 is more complete than for any other fruit crop. 



Flower induction with NAA has certain drawbacks. Part of these 

 have already been overcome. Thus, the compound causes a peduncle 

 which is more slender than usual. This may result in a loss of fruit due 



