Academe Research Journals

International Journal of Agricultural Science Research

Full Length Research Paper

Response of rice landraces and promising cultivars to nitrogen fertilizer application on sloping uplands

Khamdok Songyikhangsuthor¹*, Somphong Sybounheuang¹ and Benjamin K. Samson²

¹Northern Agriculture and Forestry Research Center (NAFReC), Houay Khot village, Xieng Ngeun district, Luang Prabang province, P.O.BOX 487, Lao PDR.

²International Rice Research Institute (IRRI), Lao PDR Office, Lao PDR.

*Corresponding author. E-mail: khamdoks@yahoo.com.

Accepted 16 September, 2014

Abstract

This study aimed to determine appropriate nitrogen fertilizer levels for upland rice. The study was designed to detect genotype × fertilizer interactions. The trial included five fertilizer treatments: control, 30, 60, 90 and 120 kg/ha of nitrogen. Six cultivars were included in the trial: 1) Makhinsoung, 2) Nok, 3) Non, 4) IR55423-1, 5) B6144F-MR-6 and 6) IR60080-46^a. The result showed that nitrogen fertilizer at 30 kg/ha increased rice grain yields in improved non-glutinous lines, and 50 kg/ha increased rice grain yields in the traditionally introduced cultivars. Highly significant difference was observed between fertilizer treatments (probability value was 0.000). The effect of the yield’s increase was about 29 to 36% from the control to the improved lines, while the response range was from 25 to 29 kg/unit of nitrogen. The traditionally introduced cultivars’ yield increased from about 25 to 34% for the control, whereas the response unit range was from 13 to 18 kg/unit of nitrogen. The fertilizer and cultivar interactions were also observed to be significant in the trial (probability value was 0.01). However, weed biomass decreased with fertilizer application, probably as a result of the inhibition of weed growth due to increased rice growth and earlier rice canopy closure in the plots which had been fertilized.

Key words: Upland rice field management, fertilizer applications, upland rice cultivars.