Abstract:

Using straw carrier-based Piriformospora indica biofertilizer as the experimental material, three treatments, biofertilizer solution 1 (BFS1), biofertilizer solution 2 (BFS2) and sterile water as control (CK), were set up to determine germination potential and germination rate of rice seeds. Three fertilizer treatments (BF1: 75% compound fertilizer +25% biofertilizer 1, BF2: 75% compound fertilizer +25% biofertilizer 2 and CK: 100% compound fertilizer) and two fertilization time treatments (15 days before transplanting and at transplanting) were set up to determine root morphological indices, leaf photosynthetic indices, seedling agronomic traits of rice seedling and colonization of Piriformospora indica. Results showed that germination of rice seeds were inhibited, and germination time was delayed by 1−2 days, and germination rates were significantly reduced by 8.7 percentage points and 52.0 percentage points by BFS1 and BFS2, respectively (P<0.05). Growth of rice seedlings was promoted by straw carrier-based Piriformospora indica biofertilizer, and a better effect was shown under BF2 treatment. Compared with CK, plant height, fresh weight above ground, root weight, weight per plant and length of the longest leaf were significantly increased by 34.5%, 76.0%, 47.0%, 54.7% and 53.9%, respectively, and total root length, root diameter, projected area, surface area, root volume and root tip number were significantly increased by 24.3%, 39.4%, 101.9%, 95.3%, 188.3% and 98.3%, respectively, and the content of chlorophyll b was significantly increased by 51.5% under BF2 treatment (P<0.05). Compared with fertilization at 15 days before transplanting, root diameter, projection area, root volume and number of root tips were significantly increased by 19.2%, 10.5%, 55.6% and 45.7%, respectively, and root activity, chlorophyll a content and carotenoid content were significantly increased by 27.9%, 10.7% and 16.9%, respectively, and stem length and longest leaf length of rice seedlings were significantly increased by 8.2% and 10.5% under fertilization at transplanting treatment (P<0.05). In conclusion, straw carrier-based Piriformospora indica biofertilizer solution inhibited seed germination, prolonged germination time and increased growth difference among rice seeds. The combined application of BF2 and compound fertilizer at transplanting could improve the overall quality of rice seedlings and show a better promoting effect. Combined with previous experimental results, it is suggested that the low concentration (25%−50%) of biofertilizer solution should be selected at germination stage of rice seeds, and 75% compound fertilizer and 25% biofertilizer 2 should be co-applied at transplanting. 

Key words: Piriformospora indica, Biofertilizer, Straw, Root morphology, Agronomic traits