Tropical & Subtropical Fruits

Degree of bienniality in hybrids having a 'regular bearer' in its parentage

• On account of having 'regular bearer' acclaim, Neelum was invariably involved in developing 'regular bearing' hybrids. The inheritance studies in mango are quite meagre. Majumdar et al. (1972) have made only some preliminary studies. According to them Neelurn has a typical phenotypic character in the behavior of fruited shoots which has relationship to annual bearing. It was inferred by them that the fruited shoots are capable of developing lateral shoots sooner after harvest of fruit in June in 'on' year and such lateral shoots are capable of attaining quicker physiological maturity. Consequently they differentiate fruit buds in the ensuing period (Oct.-Nov.) critical for fruit bud differentiation (FBD). Such differentiated shoots would develop crop in the following (second year) fruiting season (Fig. 8.2). Thus, according to them, any offspring expressing this phenotypic character would be a 'regular bearer' like Neelum. They Indeed observed the expression of this character in Neelum x Dashehari cross that was later named as Mallika which was claimed to have a 'strong tendency' for regular bearing. However, later observations showed that Mallika did not turn out to be a regular bearer.
• Moreover, when Neelam was observed at Dharwad and Raichur condi¬tions, the said phenotypic character was only feebly expressed and not many such early produced laterals on fruited shoots showed capability for differen¬tiating fruit buds (Rao et al., 1990) for cropping in the following year. Thus, the phenotypic character as proposed by Majumdar et al. (1972) could not be taken as a reliable character in so far as their capability for developing flowers in the following 'off year was concerned.
• Under Raichur conditions, Cv. Baneshan and hybrid Neeleshan (Neelum x Baneshan) have maintained lower degree of bienniality (Table 3). Whether Neeleshan has inherited the weak bienniality character of its male parent Baneshan however, remains to be genetically assessed.
Table: Degree of bienniality in successive cropping in hyorid Neeleshan in relation to its parents - Neelum and Baneshan
Study period	Degree of bienniality (% deviation in year-to-year yield)
	Cv. Neelum	Cv. Baneshan	Hyb. Neeleshan
8-year period	51.4	31.7	46.4
7-year period	56.0	32.7	39.8
6-year period	56.4	28.4	30.2
5-year period	46.2	24.0	23.2
4-year period	48.3	16.0	11.0
3-year period	36.5	21.0	15.5
2-year period	57.0	27.0	22.0
Mean of 7 years	50.2	25.8	26.9
Mango varieties are heterozygous. As such, it is doubtful whether the 'regular bearing' character, if any, gets inherited in off spring when crossed with choice varieties and at the same time retain the quality of choice variety in off-spring.