Relationship between nutrient element content of the index leaf and cane yield and juice quality of sugarcane genotypes

Abstract

The nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) content of the index leaf (whole third leaf) of eleven genotypes of sugarcane [Co 7717, CoJ 64, CoP 84211, CoH 92, and CoH 99 (early maturing); CoS 767, CoH 3, and CoH 108 (mid maturing); and Co 1148, CoH 35, and CoLK 8102 (late maturing)] were determined at the maximum growth stage of the crop. The elemental contents were correlated with cane yield and juice quality parameters [% sucrose, % commercial cane sugar (CCS), and sugar yield] at harvest. The N, P, K, Fe, Mn, Zn, and Cu contents of the third whole leaf for all eleven genotypes ranged (mean in parenthesis) from 1.46–1.80 (1.62), 0.20–0.37(0.30), 1.39–1.88 (1.67)%, and 376–1095 (613), 58–155 (98), 53–99 (74), and 8–14 (11.5) ugg1 of dry weight, respectively. Among the eleven genotypes, CoJ 64 had lowest N, P, and K contents in their index leaves as well as the lowest cane yield, % sucrose, and sugar yield, whereas CoH 35 had highest, followed by CoH 108 for these parameters. The leaf N, P, and K contents showed significant linear positive correlations with cane yield (r=0.84, 0.79, and 0.87, respectively), % sucrose (r=0.70, 0.68, and 0.65, respectively), and sugar yield (r=0.89, 0.81 and 0.90, respectively). Among the micronutrients, leaf Cu had a linear positive correlation (r=0.61) with cane yield. The multiple regression of cane yield with N, P, K, Zn, and Cu explained 93% of the variation, whereas the multiple regression of % sucrose and % CCS with N, P, and K leaf content and sugar yield with N, P, K, and Cu explained 82%, 84%, and 95% of the variation, respectively.