Tanggap fisiologi akar sorgum (Sorghum bicolor L. Moench) terhadap cekaman aluminium dan defisiensi fosfor di dalam Rhizotron

Abstract

A study on physiological mechanism of sorghum to aluminum (Al) toxicity and phosphorous (P) defi ciencies was conducted using several sorghum genotypes in rhizotron. The study was conducted in the greenhouse of the University Farm, Bogor Agricultural University from August to October 2009. The experiment was carried out as a Factorial experiment in a Completely Randomized Design with three replications. The fi rst factor was sorghum genotypes consisted of Numbu (tolerant) and B-75 (sensitive), and the second factor was combination of lime and phosphorous fertilization consisted of: no lime-no P (R1), no lime-low P (R2), no lime-suffi cient P (R3), lime-no P (R4), lime-low P (R5) and lime-suffi cient P (R6). The results showed that all variables were signifi cantly affected by the interaction of media and genotype, except for length of shoot and total P uptake. Under low P and Al toxicity, sorghum variety Numbu showed a higher nutrient effi ciency than B-75 with ability of forming greater dry mass. The sensitive genotypes showed a higher nutrient uptake but a lower P nutrient use effi ciency under Al toxicity and P defi ciency. Total P uptake and P nutrient use effi ciency were highly correlated with root growth and dry material accumulation.