Carbon isotope discrimination: Potential for screening salinity tolerance in rice at the seedling stage using hydroponics

Abstract

Rice is a moderately salt-sensitive crop species and soil salinity is the single most widespread soil toxicity problem facing rice production. The quantification of salinity resistance poses serious problems in the field because of climatic factors and field heterogeneity. In the present study, rice germplasm obtained from the International Rice Research Institute (IRRI), Philippines, was screened in a naturally lit (11 h daylight) glasshouse-based hydroponics unit at two salinity levels (4 and 6 dS/m). Phenotypic performance based on survival of tolerant, moderately tolerant and susceptible isogenic lines along with tolerant and susceptible parents was evaluated after 10 and 13 days of salt stress. Plants were harvested after second scoring and carbon isotope discrimination in the leaves (Δ1) was measured. Δ1 ranged from 19.5 to 22.9‰. A highly significant negative correlation (r = -0.95, P < 0.001) between Δ1 and visual scoring was observed. Data indicated the potential of using Δ1 a physiological indicator for salinity tolerance in rice seedlings grown in hydroponics. © 2005 Blackwell Verlag.