Indirect effects of aluminum on the reflectance properties of rice cultiyars differing in aluminum tolerance

Ten-day-old seedlings of six rice (Oryia sativa L.) cultivars were grown hydroponically for 30 days in a nutrient solution containing 222| iM aluminum (Al)/L. Leaf reflectance properties were determined at visible (400–700 nm) and near infra red (700–1100 nm) wavelengths under controlled environmental conditions. For the Al-tolerant cultivars of rice, there was no significant difference in the visible and near infrared reflectances. By contrast, the Al-susceptible cultivars showed a prominent increase in reflectance in both the visible (with minor shift in the peak) and in the near infrared region. Foliar chlorophyll content decreased significantly in the Al-susceptible cultivars but not in the Al-tolerant cultivars. Further, mineral uptake, uitilization efficiency, and pigment contents have been correlated with these reflectances. In addition, there was no correlation between foliar Al content and changes in the reflectance of the Al-treated susceptible cultivars.