Resumen de Effect of Pseudomonas syringae subsp. syringae on yield and biomass distribution in wheat

Alberto Julián Valencia Botín, Leopoldo E. Mendoza Onofre, Hilda Victoria Silva Rojas, E. Valadez Moctezuma, Leobigildo Córdova Téllez, Héctor Eduardo Villaseñor Mir

• The effect of Pseudomonas syringae subsp. syringae on seed yield, aerial biomass production and partitioning in wheat (Triticum aestivum L.) is unknown. A field experiment was carried out in two locations of the Mexican Highlands (Montecillo and Chapingo) to evaluate the response of two wheat cultivars (�Seri M82� and �Rebeca F2000�) to four inoculum rates (106, 8, 10 cfu mL�1, plus a control without inoculum). Disease incidence and severity, seed yield, seed number and seed size were measured. At flowering and seed physiological maturity, aerial biomass production and distribution of main stem, secondary stems and total plant were recorded. Source-sink relationships during the grain filling period were estimated. Higher values of disease incidence and severity were observed at Chapingo; the same traits were also greater in �Seri� than in �Rebeca� at both sites (p < 0.05). Seed yield, seed number and seed size of �Rebeca� were higher (p < 0.05) than that of �Seri�. The pathogen reduced (p < 0.05) plant height, seed yield, seed yield components, and biomass production of most organs of main and secondary stems. The magnitude of the reductions was similar in both cultivars at both sites. The effect of the bacteria at each location was higher (p < 0.05) at greater doses affecting seed number more than seed weight. Stems prevailed as sink organs, while laminae, sheaths, spikes, and other vegetative parts predominated as source organs. Plant disease records should complement crop physiological variables to evaluate and to explain bacterial disease effects