Genetic variability and response of some sugarcane varieties to application methods of N-fixation organism (Azospirillum brasilense) under different inorganic nitrogen levels

Abstract

Two field experiments were conducted at Mallawi Agric. Res. Station, El-Minia Governorate, Egypt, during 2018-19 and 2019-20 seasons to evaluate the performance of four sugarcane varieties (G.T.54-9, G.84-47, G.2003-47 and G.2004-27) in response to Azospirillum brasilense application methods (without, soil drench and inoculation of cane setts) and inorganic-N levels (150 and 200 kg N / fed) following split plot design. Variety G.T.54-9 surpassed the other varieties in millable cane weight, cane and sugar yields / fed. There was an insignificant difference between GT.54-9 and G.2004-27 varieties in cane yield / fed in both seasons and sugar yield / fed in the 1st one. Inoculating cane setts with Azospirillum was more effective on most of the studied traits than soil drench. Adding 200 kg N/fed significantly increased brix %, sucrose %, cane and sugar yields / fed, while purity % was reduced. The effects of the significant interactions among the studied factors on the recorded traits were discussed. Correlation between cane yield and its components was highly significant with positive directions across seasons. Cane yield and millable cane weight recorded the highest heritability %, genotypic and phenotypic coefficient of variation. Significant genotypic effects indicated existence of the genetic variability among varieties and the possibility of utilizing them in genetic improvement. Variety G.T. 54-9 attained the highest net return, followed by G. 2004-27, G. 2003-47 and G. 84-47. Under conditions of the present work, inoculating cane cutting seeds of G.T. 54-9 and / or G. 2004-27 sugarcane varieties with 2 packets / fed (one packet = 400 g) containing Azospirillum brasilense bacteria + 150 kg N/fed could be recommended to attain the economical cane and sugar yields.