Maximum diurnal trunk shrinkage is a sensitive indicator of plant water, stress in Diospyros kaki (Persimmon) treesPersimmon tree (Diospyros kaki L.f.) is a deciduous fruit tree included in the so-called group of minor fruit
tree species. Worldwide, it is not widely grown but, nowadays, Kaki culture is of some importance in the
south-east of Spain because of the high fruit commercial value. Currently, neither it is known about Kaki
trees water needs, nor crop responses to the irrigation regime. The objective of the present research was
to assess the feasibility of using maximum diurnal trunk shrinkage (MDS) as a plant water stress indicator
for Kaki trees. During two drought cycles, in trees under either full or deficit irrigation, the MDS obtained
by means of LVDT sensors was compared with a reference indicator of fruit trees water status, the midday
stem water potential (stem). In addition, stomatal conductance and fruit diameter variations were also
followed. As water restrictions began, there was an immediate increase in MDS, in correspondence with
a decrease in stem. Pooling data from both drought cycles and irrigation regimes, MDS and stem were
linearly correlated (r2 = 0.77***). The magnitude of differences between well watered and deficit irrigated
trees was much larger in the case of MDS than for stem. However, the tree-to-tree variability of the MDS
readings was three times higher than for stem; average coefficient of variation of 14% and 38% for stem
and MDS, respectively. Overall, results reported indicated that MDS is a sensitive indicator of Kaki water
status and it can be further used as an irrigation scheduling indicator for optimum irrigation management
of this crop. However, the large MDS tree-to-tree variability should be taken into account when selecting
the number of trees to monitor within an orchard