Physiological responses of allelopathic rice accessions to low phosphorus stress

Physiological responses of rice accessions, PI1312777 (allelopathic) and Lemont (non-allelopathic) to phosphorus supply were evaluated in hydroponics in a greenhouse experiment. Under the low phosphorus supply, the weed-suppressive potential of PI312777 was enhanced and inhibited the morphological traits of barnyardgrass; besides, the root length of PI312777 was enhanced and that of Lemont was reduced. There were no decreases in plant height and dry weight of PI312777, but these were significantly reduced in Lemont. The contents of soluble sugar and protein were increased in PI312777, but these were decreased in Lemont. Compared to control, all photosynthetic physiological indices in PI312777 were slightly decreased in low P condition but were increased in Lemont. Furthermore, the uptake efficiency of nitrogen and potassium in two rice accessions was enhanced under low P treatment, but phosphorus uptake efficiency was decreased. At low P supply, the nitrogen, phosphorus and potassium utilization efficiency was higher in allelopathic rice ‘PI312777’ than in non allelopathic rice ‘Lemont’. The differential expression of key enzymes involved in photosynthesis and nutrient absorption, was higher in allelopathic rice than in non-allelopathic rice under low P dose. This study confirmed that allelopathic rice ‘PI312777’ maintained high photosynthesis and nutrients absorption than non-allelopathic ‘Lemont’.