Absorption of P by Cattleya 'Trimos' from Foliar and Root Applications

[thefish1337]

Absorption of P32 by Cattleya'Trimos' from Foliar and Root Applications

Please read the Methods Section before critiquing the results, they did a really good job of isolating variables.

Results/Discussion:

Effects of various methods of application and translocation of P32 in Cattleya 'Trimos' plants are summarized in Tables 1 and 2.
Method of application had no effect on the amount of P32 in the first mature leaf (Table 1) and, generally, the amount of P32 increased with time. This movement would be expected since experiments by Silberstein and Wittwer (9) indicated movement of P32 was toward the growing points and younger leaves.
More P32 was found after 24 hours in the second pseudobulbs of plants having P32 applied to the foliage than those having it applied to the medium. Obviously, P32 was absorbed foliarly by Cattleya 'Trimos' and since the entire 5 microcuries were applied to the leaf surface just above this pseudobulb, it would tend to become concentrated in this storage organ whereas the P32 applied to the medium was spread over a larger area and not all of it was in immediate contact with plant roots. Work by Thorne (10) indicated that P absorbed foliarly increased as relative humidity increased around the plants. Enclosing the sprayed leaf in a polyethylene bag increased the humidity around treated leaf and, thus, probably helped increase absorption of P32. Thorne also indicated that 90% of P32 applied to the foliage was absorbed, while in this experiment only about 40% was recovered (Table 1). This is not necessarily in disagreement with the work of Thorne, since plants had 8-10 pseudobulbs with leaves, and only 2 leaves and pseudobulbs were analyzed for P32. The leaf on which the material was applied was not analyzed and this should have been high in P32.
The third leaf and pseudobulb (Table 1) also contained P32 which increased in the tissue with time between Vz hour and 120 hours. There was more P32 in both tissues at 120 hours from foliar application.
Effects of root age on P32 absorption are summarized in Table 2. Concentration of P32
was the greatest in the pseudobulb behind the cut 24 hours after application of the material.
These data indicate that roots 3 to 4 years old are actively absorbing nutrients from the med
ium. There was no difference in the amount of P32 in the leaf immediately in front of or behind the cut rhizome after 120 hours.
One-half hour after application, sufficient P32 had been absorbed and translocated through out the areas sampled to be analyzed. These findings agree with the work of Wittwer and Ludahl working with tomatoes, however, in the case of chrysanthemums and soybeans P32 could not be detected until 2 hours after it had been applied. This variation between plant genera
can be expected due to taxonomic variations.