Less can make more – revisiting fleshy fruit quality and irrigation in horticulture
Résumé
Global climate change entails many threats and challenges for the majority of crops. Above all,
a reduction in yield is expected in many parts of the world, and drought is generally believed to
represent one of the most important negative results of climate change. Fruit crops will certainly
also suffer from the increased extension of drought conditions; however, yield is arguably not
as important for fruit as for grain crops or oil crops. Yield does matter for fruit crops, but quality
criteria are as important if not more important. Fruits are expected to supply health benefits
and to bring hedonistic pleasures associated with specific aromatic compounds. We may thus
distance ourselves from the dominant deleterious effect of drought on crop performance and
consider the potential benefits. Fruits from drought-stressed plants may in particular display a
higher content in health-promoting phytochemicals. The stimulation of secondary metabolism
following water stress may also be beneficial to plant natural defences. However, current results
also strongly suggest that taking advantage of stress will require a better understanding of the
underlying mechanisms of drought adaptation. Conducting laboratory studies on the effect of
a single severe stress applied during a very short period of time should be avoided in the future.
Instead, one should examine the effects of variable and repeated periods of drought applied at
different stages of the crop cycle, possibly in combination with other forms of stress, as these
conditions reflect free living crop conditions more accurately. Integrated models must be developed
to address the complexity of adaptation processes involved and to generate novel research
ideas and avenues for plant physiologists. We also require novel monitoring tools to assess the
level of fruit/plant stress, such as volatile organic compounds (VOC) signatures and parameters
derived from measurements of chlorophyll fluorescence. Fortunately, the information analysed
as part of this review is sufficiently mature and promising to encourage researchers shifting their
approach to drought research versus fruit quality.