A field experiment has been carried out in Valenzano (Bari) to study the response of potato crop to different water regimes (100%, 50%, rainfed) and kaolin applications. Growth and yield parameters of potato were significantly affected by water supply. Marketable yield reached 35 t/ha under full irrigation. It was reduced by 23% and 51% in the case of 50% irrigation and rainfed treatments, respectively. Marketable normalized water productivity values were 11% and 3% higher in fully irrigated and 50% irrigated treatments, as compared to rainfed. No significant difference has been observed among kaolin treatments for growth, yield and efficiencies in the use of resources (water and radiation). Leaf gas exchange was significantly reduced by water deficit and, to a lower extent, by kaolin application in two irrigated treatments.
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Accordingly, at canopy scale, assimilation and evapotranspiration were reduced by kaolin treatments up to 15 and 5%, respectively. This behavior is explained by the increase in plant temperature at both leaf and canopy scales: it increased by 1-2°C after kaolin application in irrigated treatments. The opposite behavior was observed for rainfed treatments.
