As photosynthesis is the basic process during which light energy is absorbed and converted into organic matter, the importance of the plant pigment chlorophyll (a and b forms) as an intermediary in the transformation of the absorbed solar energy and its activity in the process of photosynthesis and synthesis of organic substances in plants is crucial. Therefore, this paper provides an overview of methods for monitoring the optical activity of chlorophyll molecules and methods (non-destructive and destructive) for quantification of chlorophyll in plants. These methods are used to estimate the effects of different stress factors (abiotic, biotic and xenobiotic) on the efficiency of photosynthesis and bioproductivity, aiming to assess the impact that these limiting factors have on the yield of various cultivars. Besides, those methods for the analysis of chlorophyll optical activity and/or content are appropriate for assessing the reaction of weed species to different agricultural practices (mineral nutrition, treatment by herbicides, etc.) and studies of different aspects of weed ecophysiology and their influence on crop harvest.
Drought stress is one of the most important factors affecting plant growth. Plant growth under drought stress may be enhanced by the application of microbial inoculation including plant growth-promoting Rhizobacteria. This research was conducted as a factorial experiment in a completely randomized design. The first factor included the bio-fertilizer (A) and control (without bio-fertilizer). The results showed that treatment microbial inoculation level had the highest effect on increasing photosynthetic pigments (p<0.01 ). While the lowest amount of photosynthetic pigments occurred in treatment A. The highest and lowest shoot fresh. weight was belonged to the treatments respectively (p<0.01). The results showed that the use of bio-fertilizers separately had more positive effects on the nutrients uptake of Juniperus phoenicea. In general, the results of this study suggest that growth-promoting bacteria as biofertilizers have a greater effect on growth, photosynthesis pigments and nutrient uptake of Juniperus phoenicea. The use of microbial inoculation indicated that the use of microbial isolates in agriculture increases plant productivity and its resistance to diseases and other influences such as drought, stress and lack of nutrients and provides it with important needs.
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