Redroot pigweed’s (Amaranthus retroflexus L.) allelopathic effects on growth and physiological parameters of lettuce seedlings

Allelopathy is one of the most important interactions among plants. Weeds extracts have an allelopathic potential thus lead cause decline in growth and development of other plants. Redroot pigweed is one of the most common weeds in the world-wide and obtained extracts from it, have the allelopathic effects as well. In order to evaluation of growth aspects of redroot pigweed allelopathic effects on the lettuce seedlings, an experiment was conducted as factorial based on completely randomized design with three replications. Lettuce seeds were sowed on Petri containing sterile filter paper at greenhouse conditions and treated with amaranth different concentration leachate including 0, 0.025, 0.05, 0.075, and 0.1%. Germination decline, decreasing in shoot length,increasing seminal root and seedlings length, decreasing shoot to root length ratio were the effects of redroot pigweed leachate on growth and development of lettuce seedlings which were observed in the treated plants. Physiological effects of redroot pigweed on lettuce seedlings were including alteration on the function of the enzymatic antioxidant system (catalase and peroxidase) and non-enzymatic antioxidant system (phenols and flavonoids) and amounts of total protein as well. It is worth noting that with increasing leachate concentration, the mentioned effects were accelerated. Considering that lettuce due to the unique characteristics is a model plant in the allelopathic researches, the study of more physiological as well as molecular aspects of amaranth allelopathy is suggested

Keywords:

Allelopathy , Redroot pigweed , Growth parameters , Antioxidant system , Lettuce seedling