HORMONAL STATUS OF DEVELOPING SUB-TROPICAL PEACHES

The concentrations of auxins, cytokinins, gibberellins and abscisic acid (ABA), along with certain other metabolites, in the seeds and fruit flesh of two sub-tropical peach cultivars (Sharbati and Flordasun) were estimated. The usual methods of purification, paper chromatography and bioassay were used for the measurement of the hormones, which were made at each of the three stages of fruit growth.

Table 1 - The hormonal content of the fruit (flesh + seeds) of two peach cultivars

Sharbati

Flordasun

Stages	I	II	III	I	II	III
Auxins	H	M	H	H	M	H
Cytokinins	H	M	L	H	H	L
Gibberellins	M	H	M	M	M	M
ABA	H	M	H	H	M	M

H = High

M = Moderate

L = Low

Fruit growth in the two peach cvs Flordasun (early) and Sharbati (late) followed the usual double sigmoid curve. In Flordasun, the middle slow growth phase was of two weeks' duration whereas in Sharbati, it lasted for four weeks. In Flordasun, the seeds produced greater amounts of cytokinins and auxins during first two stages but gibberellins were more during stage I and ABA during stage III. In Sharbati, the seed remained a stronger source of cytokinins during the first two stages, while auxins were high during stage I, ABA during stage II and gibberellins during stage III; otherwise the flesh dominated in these hormones. In both cultivars stage I was associated with highest level of cytokinins, auxins and ABA and moderate level of gibberellins. In Flordasun, stage II was dominated by moderate level of ABA and gibberellins but in Sharbati gibberellins showed the peak whereas ABA was at its lowest concentration. There was no difference in cytokinins and auxins in Flordasun and Sharbati fruit during stage III. The gibberellins were moderate in both cultivars and declined in the last 3 weeks in Flordasun. The ABA was the highest in Sharbati but moderate in Flordasun which showed increased amounts in the last 3 weeks.