Photosynthetic performance of young maize (Zea mays L.) plants exposed to chilling stress can be improved by the application of protein hydrolysates

Biostimulants offer a novel approach for the regulation of crucial physiological processes in plants. Recently, it has been observed that the application of biostimulants on both seeds and plants may ameliorate to some extent the negative effects of abiotic stresses such as drought, heat, salinity, and others. In the climate conditions of Bulgaria, the early developmental stages of warm climate crops, like maize, often occur under suboptimal temperatures. Although the mitigation of abiotic stress is perhaps the most frequently cited benefit of biostimulant formulations, little is known about their influence on chilling-stressed plants. The aim of our study was to evaluate the effects of a biostimulant from the group of protein hydrolysates on both the growth and the photosynthetic performance of chilling-exposed young maize plants grown in controlled environment. Here, we report that application of a protein hydrolysate increased the performance of chilled maize plants, as demonstrated by leaf gas exchange, photosynthetic pigment content, and chlorophyll fluorescence, but did not affect their growth. Nevertheless, based on the better preserved photosynthetic performance of the biostimulant-treated maize plants exposed to chilling, we assume that under subsequent favorable conditions their growth would recover more quickly as compared to the untreated ones.