Analysis of Germination, Seedling Growth, Photosynthetic Efficacy and Antioxidative Enzyme Activity in Sunflower Under Allelopathic Stress Caused by Cynodon dactylon L.

Obnoxious weeds have always been troublesome for agricultural crop plants. Their phytotoxic nature negatively alters germination, growth and productivity of neighboring plants. Cynodon dactylon L. is a very common and rapidly multiplying weed of northern Indian plains. Present study aimed to understand the degree of its phytotoxicity and its allelopathic impact on seed germination and seedling growth of commercially important sunflower crop plants. As we know that healthy seedlings ensure healthy yields so it is necessary to understand the possible threats to seedling growth. Experiments were carried out with the leachates of two different plant parts of Cynodon dactylon L. (donor plant) viz. rhizome and leaf on germination and seedling growth of sunflower (recipient plant). Results showed the negative correlation of seed germination and seedling growth with both rhizome and leaf leachate. However, more severe growth inhibition was recorded when seeds were treated with a higher concentration of rhizome leachate. Photosynthetic pigments and protein content were also decreased significantly under leachate treatment. However, carotenoids were increased under allelopathic stress. Increased SOD and CAT activity in sunflower seedlings under treatment with a higher leachate concentration indicated the production of reactive oxygen species (ROS) due to the impact of oxidative damage caused by donor plant. Present study highlights the need of control of weed prior to sowing of crop seeds and also provides an alternative to utilize harmful weeds into useful bioherbicides.