Tropical & Subtropical Fruits

Variability in the expression degree of bienniality

• It is observed that the problem of bienniality in cropping is expressed in varying degree in different varieties and hybrids. In general, the choice varieties have recorded higher degree than the mediocre varieties. An analysis of 7-year yield data (Table 1 a & lb) of adult mango varieties and hybrids grown at Raichur (North Karnataka) has revealed that the highest degree of bienniality is expressed in choicest variety like Alphonso. The Cv. Baneshan, the most popular commercial variety of Andhra Pradesh, though not the choicest one, has recorded the weakest bienniality; the Cv. Neelum which has a claim as a 'regular bearer' in the common parlance was graded as 'moderately biennial' and the Cv. Totapuri, the other popular cultivar having the 'regular bearer' acclaim was observed to be weakly biennial. However, it is interesting to note that some of the hybrids having Neelam in their parentage have recorded weak bienniality.
• Thus, it appears that there exists no such variety as 'regular bearer' in its literary sense. According to Rao et al., (1990), giving 'regular bearer' acclaim to some varieties like Neelam in common parlance may be an illusion since such varieties too in reality have recorded lower yields followed by year of higher yield. At best, they suggested that such varieties could be classified as weakly or moderately biennial types as against the strongly biennial types like Alphonso.

Table 1a : Yield potential and degree of bienniality in some mango varie­ties and hybrids

Variety/Hybrid	Mean number of fruits/ tree/year	Bienniality
		Deviation in successive croppings (43/0)	Class
Khadar	425	42	Moderately biennial
Neelum	644	40	Moderately biennial
Baneshan	697	22	Weakly biennial
Hyb. Neeleshan (Neelum x Baneshan)	1129	27	Weakly biennial
Hyb. AU-Rumani (Rumani x Mulgoa)	438	28	Weakly biennial
Hyb. Neelgoa (Neelum x Yerramulgoa)	773	38	Moderately biennial
Hyb. Neeluddin (Neelum x Himayuddin)	707	33	Moderately biennial