Effect of Nitrogen and Potassium Stress and Cultivar Differences on Potassium Ions and Nitrate Uptake in Sugarcane |
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| Authors: | Ranjith Subasinghe |
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| Institution: | Hawaii Agricultural Research Center , Aiea, HI, USA |
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| Abstract: | ABSTRACT This study was conducted to evaluate the effect of nitrogen (N) and potassium (K) stress on nitrate (NO3 ?) and potassium ion (K+) uptake of two sugarcane (Saccharum officinarum L.) cultivars known to differ with regard to their resistance to drought and salinity stress. The plants were hydroponically grown in a greenhouse and subjected to varying levels of N and K. Nitrogen and K stress increased root affinity for NO3 ? and K+ absorption by increasing apparent maximum uptake rate (Vmax) and decreasing apparent affinity (Km) for NO3 ? and K+ uptake in both cultivars. In addition, dry-matter allocation to roots increased with decreasing N and K supply. The results suggest that the acclimation to long-term N starvation in sugarcane involves regulation of both nitrate-specific assimilatory steps and growth responses. The cultivar ‘H69-8235,’ which was drought and salinity resistant, showed greater adaptability to a low- nutrient environment due to its higher root allocation and affinity for NO3 ? and K+ under N and K stress, suggesting that the resistance of sugarcane to multiple stresses may involve a general stress-response system. |
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| Keywords: | affinity hydroponics kinetics nitrate potassium stress sugarcane uptake |
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