Growth, physiological status, and yield of salt-stressed wheat (<i>Triticum aestivum</i> L.) plants affected by biofertilizer and cycocel applications

Abstract

This factorial study was conducted based on randomized complete block design with three replications in a greenhouse during spring 2015 to investigate changes in dry matter mobilization, grain filling period, and some physiological characteristics of wheat. Treatments were four salt levels [0 (S1), 30 (S2), 60 (S3), and 90 (S4) mM sodium chloride (NaCl) equivalent to 2.76, 5.53, and 8.3 dS m−1, respectively], four biofertilizers levels [(no biofertilizer (F0), seed inoculation by Azotobacter chroococcum Beijerinck strain 5 (F1), Pseudomonas putida (Trevisan) Migula strain 186 (F2), both inoculation Azotobacter + Pseudomonas (F3)], and three cycocel levels [(without cycocel as control (C0), application of 600 (C1), and 1000 (C2) mg L−1)]. Salinity stress increased leaf electrical conductivity and decreased chlorophyll index, quantum yield, relative water content, and stomata conductance. However, the application of cycocel and biofertilizer reduced the negative impacts at each level of salinity tested. When treated with cycocel, salt stressed plants demonstrated a significant decrease in stomata conductance compared to the salt-treated plants with no cycocel. The results revealed that the maximum shoot and stem dry matter mobilization (0.89 and 0.67 g, respectively) and contribution of stem reserves to grain yield (38.01%) were observed in salinity severe stress (90 mM) and no cycocel application. The application of Azotobacter + Pseudomonas had the greatest grain filling rate (0.002 g day−1) without salinity stress. The greatest grain filling period (43.26 days) was achieved by the highest cycocel level without salinity stress. The application of biofertilizer and cycocel as F3C2 had 24.7% more grain yield in comparison to the controls.