Agriculture Reference
In-Depth Information
irrigation (
WUE
irr
). Results showed that
WUE
ET
>
WUE
irr
due to the fact that
measured ET was less than the daily irrigation. Results also showed that the
ratio between the two fluxes, namely,
WUE
ET
, was essentially unchanged
with plant growth (with an average of 0.00894 for small plants and 0.00946
for large plants). On the other hand,
WUE
irr
(based on irrigation) increased
with plant growth suggesting that the crop was over-irrigated during its initial
growth stage. This finding may be important for improving irrigation man-
agement and increasing water savings. Dicken et al. (
2013
) also presented
diurnal courses of the
WUE
ET
(daily values only, 10:00-17:00) for small and
large banana plants in the screenhouse. Larger plants'
WUE
ET
was essentially
unchanged during the day whereas for the smaller plants a small increase (not
significant) of WUE was observed during the day. The results also showed
that during the morning hours (10:00-12:00)
WUE
ET
for the larger plants was
significantly higher than that for the smaller plants. This, together with the ob-
servation by Dicken et al. (
2013
) that photosynthesis per leaf area was about
the same for both cases may indicate over-irrigation of the smaller plants in
the early morning. Such observations could assist growers in increasing water
use efficiency of screenhouse banana plantations by fine tuning irrigation dur-
ing the morning hours.
Irrigation Management
Irrigation management includes all measures that guarantee sufficient water supply
for plants. One could assume that for a specific plant species “only” the right wa-
ter demand should be ensured and generally, the amount of evapotranspired water
should be compensated. However, customizing irrigation is a multi-faceted activity
and the amount of water used in protected crops is still higher than the theoretical
calculated values. For instance, Fuchs et al. (
2006a
) reported that roses grown in
greenhouses on artificial substrates transpire annually an estimated 1,500 mm of
water in Israel. However, in order to prevent solute accumulation in the root me-
dium, growers use nearly twice this amount for irrigation. The excess water leaches
out, leading to a considerable waste of water and fertilizer (for water use efficiency
(WUE), see box 1; and for fertilizer use efficiency (FUE), box 2).
Questions like “how long?” (= duration), “how often?” (= frequency), and “how
much?” (= water amount), deserve answers to greenhouse management (climate
conditions) for each plant's growth phases (young or ripening stage), particularly,
to control the water status of a crop for a proposed level of plant performance.
According to Saha et al. (
2008
) targeted performance levels and optimizing
irrigation input can be used to either maximize yield or economic return, or increase
the WUE.
Different irrigation controls range from hand irrigation through to simple
timer-based to computer-based monitoring and control systems. In commercial
