The 1992 experiment allowed us to separate
the effects of providing extra water from
those of providing extra nutrients, effects that
were confounded in the 1990 experiment. When
treatments receive differing amounts of fertilizer
as well as different amounts of water (as in
1990), plants receiving more fertilizer may
have grown faster. This more rapid growth
might, in and of itself, result in greater cracking.
There is, indeed, evidence that rapid fruit
growth from any of a number of causes increases
fruit cracking. Dutch investigators reported
increased incidence of russetting (a
disorder related to cracking where minute
cracks appear all over the skin) when fruit
were developing more rapidly (Bakker and
Janse, 1988; Schilstra-van Veelen and Bakker,
1985). Our 1990 data also provide partial
support for the hypothesis that rapid fruit
growth increases cracking (Peet, 1992). Fruit
that were cracked at harvest had matured significantly
(P £ 0.05) more rapidly than
uncracked fruit (58.4 days vs. 61.8 days).
However, once cracking occurred, fruit may
have ripened more rapidly and so were harvested
sooner.