Abiotic stresses are the major environmental factors that play a significant role in decreasing plant yield and production potential by influencing physiological, biochemical, and molecular processes. Abiotic stresses and global population growth have prompted scientists to use beneficial strategies to ensure food security. The use of organic compounds to improve tolerance to abiotic stresses has been considered for many years. For example, the application of potential external osmotic protective compounds such as proline is one of the approaches to counteract the adverse effects of abiotic stresses on plants. Proline level increases in plants in response to environmental stress. Proline accumulation is not just a signal of tension. Rather, according to research discussed in this article, this biomolecule improves plant resistance to abiotic stress by rising photosynthesis, enzymatic and non-enzymatic antioxidant activity, regulating osmolyte concentration, and sodium and potassium homeostasis. In this review, we discuss the biosynthesis, sensing, signaling, and transport of proline and its role in the development of various plant tissues, including seeds, floral components, and vegetative tissues. Further, the impacts of exogenous proline utilization under various non-living stresses such as drought, salinity, high and low temperatures, and heavy metals have been extensively studied. Numerous various studies have shown that exogenous proline can improve plant growth, yield, and stress tolerance under adverse environmental factors.

Seed scientists and other plant biologists are interested in the measurement of germination because seeds from different individuals, populations, seed lots and treatments can differ in germination percentages, rate (speed) and uniformity. Mean time to germination (MGT) is a measure of the rate and time-spread of germination; however, there is a problem with using this method to calculate germination rate. MGT does not show the time from the start of imbibition to a specific germination percentage. MGT has been used to compare specific pairs or groups of means and to evaluate seed vigour. However, it is not the real time to mean germination but just an index of germination speed. Using MGT is not correct for ANOVA, post-ANOVA or the other comparison tests, because it does not show time to a specific germination percentage. Thus, we recommend that t50 be used instead of MGT. The t50 has all benefits of MGT, but it does not have the problems of MGT in treatment comparisons.