Treatment strength optimization for maize (Zea mays L.) against saline conditions using biplot analysis

Abstract

Maize (Zea mays L.) genotypes collected from different research institutes were evaluated against different standards associated with salinity tolerance/susceptibility under four variable saline treatment strengths S0.8 dSm-1 (T1; Control), S4 dSm -1 (T2), S6 dSm-1 (T3) and S10 dsm-1 (T4) to optimize treatment strengths for screening and to study genotype × environment interaction (GEI) on the basis of shoot length (SL), root length (RL), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), sodium concentration in leaf sap (Na+), chloride concentration in leaf sap (Cl-), potassium concentration in leaf sap (K+), total proline contents in leaf sap (PRO) and sodium/potassium ratio (Na+/K+). Under S10 dsm-1, genotype UAC-0020 performed relatively well based on Na+ and Cl- whereas UAC-0036 performed well for K+ and Na+/K+. UAC-0024 was most stable for SFW. Under S4 dsm-1, UAC-0028 was poor in performance for Na+, Na+/K+, SL, PRO and Cl-; similarly, UAC-0048 showed poor performance for SFW, RFW, SL and PRO; UAC-0041 and UAC-0033 posed least resistance for SL, SFW, RL and RFW, respectively. The rest of the genotypes interacted under all the variable stressful environments either positively or negatively. SL, SDW, RFW, Na+, Cl- and PRO were verified as very good indicators of salinity tolerance in maize plant. Biplot based on Principal Component Analysis (PCA) is reported as an effective technique to study GEI. S4 dsm -1 was proved as best strength to sort out susceptible and S10 dsm -1 to sort out most tolerant genotypes. The best performing genotypes could be considered for further breeding programs.