Stressful conditions, photosynthesis and plantlets production: effects and management

Photosynthesis is an essential nutritional function for plants, and a fundamental support for the stability of whole trophic networks in the biosphere. Light photons provide energy to excite chlorophyll and start the conversion of intake atmospheric CO2 and H2O into sugars, starches and phyto-glycogens. It also maintains suitable oxygen levels for supporting aerobic life. However, aerobic metabolism produces reactive oxygen and nitrogen species (ROS/RNS) as byproducts. Usually, the ROS levels can be controlled by the cellular antioxidant system, but internal and external stressing factors can overstimulate ROS generation, overwhelming the antioxidant system, and lead to Oxidative Stress (OS) and directly attack the integrity of biomolecules and impact many biological functions, such as Photosynthesis. We studied the dynamics of Oxidative Status (OSt) and its impact on Photosynthesis during the production of blueberry (Vaccinium corymbosum L.) plantlets. Blueberry plantlets are produced via micropropagation followed by greenhouse acclimatation and growth and finally shipment to producers. In this work we have studied the Oxidative Status (OSt) of plantlets along the productive process. The dynamics between hydrogen peroxide (H2O2) and Superoxide Dismutase (SOD) activity were monitored and used to implement an indicator of Oxidative Status (OSt) called Oxidative Status Rate (ROS) and correlated with Photosynthesis Rate (A) and Plantlet Viability during production. The same parameters were evaluated in plantlets developed in pots with different capacities (10, 50 and 500 cm3) during the shipment and delivery to final destination.