IRRIGATION SCHEDULING OF MAIZE AFFECTED BY PLANT GROWTH-PROMOTING RHIZOBACTERIA

摘要

A field experiment was conducted during the two fall seasons 2017 and 2018 aimed to study the irrigation scheduling and the role of plant growth-promoting rhizobacteria (PGPRs) in increasing the availability of nutrient elements as well as some indicators of popcorn maize growth. The Randomized Complete Block Design (RCBD) within the order of split plots including three replicates was used. The experiment included three levels of irrigation applied after depleting 50, 60, and 70% of the available water symbolized by S1, S2 and S3 that represented the main plots, while the subplots included the treatment of bacterial vaccine: without vaccine (control), Azotobacter, Azospirillum and Azotobacter + Azospirillum symbolized by F0, F1, F2 and F3. Results showed the superiority of the irrigation after depleting 50% of the available water in producing the highest percentage of nitrogen and phosphorus that were 0.76 and 0.42 % on average respectively for both seasons, yet in the first season they did not differ significantly from the treatment S2 producing 0.68 and 27.66% of nitrogen and phosphorus, respectively. The depletion treatment S1 (irrigation after depleting 50% of the available water) produced the highest values of root dry weight (26.25 and 27.66 g.plant(-1)) and leaf area (3562 and 367 cm(2)) in the two seasons, respectively. Treating by the PGPRs achieved significant responses. The treatment F3 gave the highest percentages of nitrogen (0.72 and 0.81%) and phosphorus (0.38 and 0.43%) in the two seasons respectively and it participated in increasing the dry weight of the root system to be 23.00 and 35.62g in the two seasons respectively compared to the control treatment producing the lowest root dry weight 21.63 and 22.60 g in the two seasons respectively, in addition to the increment in the other studied vegetative traits. We conclude that the PGPR scontributed to limit the harmful effect of water stress through increasing the element availability and enhancing the vegetative growth indicators where the two treatments Azospirillum and Azotobacter + Azospirillum achieved the best contribution.