Growth reduction in root-restricted tomato plants is linked to photosynthetic impairment and starch accumulation in the leaves

The mechanisms responsible for reduced shoot growth due to restricted root growth is still not fully understood. Therefore, this investigation was planned to determine the morphological and physiological changes induced in response to root restriction conditions and to determine the time frame within which these changes occurred. In particular, this research aims to evaluate the effect of root restriction on growth, leaf gas exchange parameters, carbohydrate production and water relations in tomato (Solanum lycopersicum L.). Our results show that growth reduction by root restriction is mainly linked to a photosynthetic impairment, caused by a concurrent limited stomatal conductance (probably driven by stomatal factors and hormonal substances) together with a strong accumulation of starch in the tissues, which led to a feedback inhibition of the photosynthetic process.