Exogenous Sucrose Enhances Growth and Physiological Performance of Tomato Seedlings Under Suboptimal Light Conditions in Passive Greenhouses

Tomato is an important crop worldwide. Commonly, the production process is initiated in nurseries that provide seedlings to greenhouse growers. Many factors influence crop production, one of which is the seedlings’ quality. Light has an enormous effect on seedlings; however, in passive greenhouses, its control is quite difficult. In this situation, plants are usually affected by low or high light intensities which induces poor growth on plants. On the other hand, there is some evidence that sucrose applications could compensate for the adverse effects caused by low light intensities and other abiotic factors like salinity, drought, and temperature. In this way, this research aimed to assess the impact of exogenous sucrose on the morphology, quality, and growth of tomato seedlings cultivated under low-tech greenhouse conditions commonly observed in tropical and subtropical commercial nurseries. Four sucrose treatments were proposed (0, 1, 10, and 100 mM). On days 28, 32, 36, 40, and 44 after sowing, several morphological, physiological and growth measurements were evaluated. Sucrose-treated plants displayed higher leaf areas and chlorophyll contents, facilitating light absorption. Therefore, the relative growth rate (RGR) was enhanced and better explained by a higher net assimilation rate (NAR). Consequently, a higher dry matter accumulation and Dixon quality index (DQI) were achieved. Plants under treatment at 100 mM exhibited the best performance.