Effects of seedling age and potassium rate on lodging related characteristics and agronomic traits of rice (Oryza sativa L.) cv. Sang Tarom

In order to investigate the effects of seedling age and potassium rates on lodging related characteristics and agronomical traits in rice, an experiment was carried out in split plot based on randomized complete block design with four replications at Mazandaran province in 2009. Main plot was seedling age in three levels 20, 30 and 40 days and sub plot was potassium rates in four levels 0, 60, 120 and 180 kgha-1. Results showed that third inter-node length, diameter and bending moment, fourth inter-node diameter and bending moment, panicle length, total tiller number per hill, filled spikelet percentage, panicle number per m2, grain yield and harvest index had significant differences (p ≤ 0.01 and p ≤ 0.05). The maximum length, diameter and bending moment of the third and fourth inter-node and grain yield were obtained with application of 180 kg K per hecare. The highest number of panicle per m2 was produced at interaction of 40 days seedling age × 60 kgha-1 and the maximum grain yield and biological yield were produced at interaction of 30 days of seedling age × 120 kgha-1. Therefore, 30 days seedling age and application of 180 kgha-1 that produced the highest grain yield, biological yield and harvest index was determined as the best treatment.