MANGO - Tropical Fruits - page 279

insect pests. Yields over many years exhibit a sigmoidal curve, initially with
low yields, increasing more rapidly and then dropping of as trees become
crowded. The period of maximum production depends upon tree growth rate;
a rapidly growing cultivar is more likely to show decreasing yields earlier, due
to crowding. Mango yield studies over a sui cient number of years involving
replicated plantings are relatively rare, due to time and cost.
In Puerto Rico, researchers determined yield potential, year-to-year
consistency of production, estimates of incremental increase in yields over age
of trees, fruit size and tree growth of 16 cultivars in their fi rst 6 crop years.
The adjusted cultivar mean yield can be separated into three yield groups,
with no signifi cant dif erences between cultivars within each group (Pennock
et al. , 1972). The high-yielding group order was 'Ruby', 'Sensation', 'Eldon'.
'Lippens' and 'Irwin'; an intermediate group 'Earlygold', 'Keitt', 'Parvin',
'Zill', 'Haden' and 'Palmer'; and a low-yield group of 'Pillsbury', 'Kent',
'Edward', 'Santaella' and 'Jacquelin'. Cultivar consistency of bearing also
gave three dif erent groupings, having dif erent cultivar make-up: 'Edward',
'Zill', 'Pillsbury', 'Ruby', 'Lippens' and 'Irwin' as regular bearers; 'Sensation',
'Santaella', 'Parvin', 'Earlygold' and 'Jacquelin' with intermediate consistency;
and 'Kent', 'Eldon', 'Palmer', 'Haden' and 'Keitt' being highly inconsistent
in yield (Fig. 10.10). The consistent-bearing cultivars with high yields were
'Ruby', 'Lippens' and 'Irwin'. 'Edward', 'Zill' and 'Pillsbury' show regular-
bearing habit but consistently produce low yields.
A mango orchard on the south coast of Puerto Rico under similar
conditions to those of the above experimental site began production about 5
Fig. 10.10. Year-to-year variation in yield of three cultivars having different bearing
habits (Pennock et al. , 1972).