This study was carried out during seasons of 1999,2000 and 2001 on four
mango cultivars (Hindy Sinnara, Dabsha, Zebda and Ewais) in 'on' and 'off years
through the period of September - February. Data were indicated that the morphological and histological stages in aU
studied cultivars were similar in 'on' and 'off-year of the two studied seasons whith
some slowly and delay in these stages in 'off-year season. The sludied cultivars and
treatments had significant effect on the beginning time and period of both the
histological and the morphological stages in all studied cullivars and the percentage of
the terminal flowery buds; the studied cultivars were affected differenUy by the studied
treatments in respect of earliness or delaying the flowering. The percentaqe of the
terminal flowery buds in 'on'· year season was more than that of 'off· year season. Also,
the studied cultivars were great differed in the number and the histological features of
these stages in all studied cultivars. Four morphological stages were determined as follows: fully swollen bud, bud
inception, developing panicle prior to fun bloom and fuUy developed panicle at full
bloom. Hindy Sinnara cultivar have nine stages (bud primordium, scales initiation, nat
flowery bud, slightly dome- shaped flowery bud, dome- shaped flowery bud, stamens
and carpel primordia, differentiation of stamens and carpel, differentiation of the upper
part of carpel and differentiation of the lower part of carpel): Zebda cullivar have eight
stages (flat flowery bud, pre-dome-shaped flowery bud, slightly dome-shaped flowery
bud, dome- shaped flowery bud, stamens primordia initation. carpel initiation, closed
differentiated flowery bud and developed ovary): Ewais cultivar have eight stages
(appearance of active tissues, conical- shaped bud, rounded bud, conical like- s'haped
grown apex, developed floral leaves, stamens and carpel primordia, differentiated bud
and pre- burst bud) and Dabsha cultivar have five stages (undifferentiated bud, Slight
probus.on, active bud, early differentiation and axillary floral bud initiation). In most
cases. the treatments of urea and its combinations caused buming of scales and
another parts of the terminal flowery bud; treatment of paclobutrazole caused excessive
differentiation of scales, NAA, SA and GA3 treatments caused some of upnormal
initiation and differentiation in the terminal flowery bods of all studied cultivars. Hindy
smnara cultivar have an early beginning lime and short period in the most stages ,while
Dabsha cullivar have delay beginning lime ,and .Iong period in most stages and Zebda
and Ewais~ cultivars came between them. These results were obtained in 'on' and                 'off .year for the two studied seasons, ".