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Wheat is a highly relevant crop worldwide, and like other massive crops, it is susceptible to foliar diseases, which can cause devastating losses. The current strategies to counteract wheat diseases include global monitoring of pathogens, developing resistant genetic varieties, and agrochemical applications upon diseases’ appearance. However, the suitability of these strategies is far from permanent, so other alternatives based on the stimulation of the plants’ systemic responses are being explored. Plants’ defense mechanisms can be elicited in response to the perception of molecules mimicking the signals triggered upon the attack of phytopathogens, such as the release of plant and fungal cell wall-derived oligomers, including pectin and chitin derivatives, respectively. Among the most studied cell wall-derived bioelicitors, oligogalacturonides and oligochitosans have received considerable attention in recent years due to their ability to trigger defense responses and enhance the synthesis of antipathogenic compounds in plants. Particularly, in wheat, the application of bioelicitors induces lignification and accumulation of polyphenolic compounds and increases the gene expression of pathogenesis-related proteins, which together reduce the severity of fungal infections. Therefore, exploring the use of cell wall-derived elicitors, known as oligosaccharins, stands as an attractive option for the management of crop diseases by improving plant readiness for responding promptly to potential infections. This review explores the potential of plant- and fungal-derived oligosaccharins as a practical means to be implemented in wheat crops.

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Physico-chemical features of chitosan affect its biological activity on plants. In this work, the influence of chitosan molecular mass in potato (Solanum tuberosum L.) yields was investigated. By using chitosan polymers of high (CH-1) and low (CH-2) molecular weight and a hydrolysed chitosan derivative (CHH), two experiments were performed under field conditions to determine the effect of these polymers on yields of two potato varieties, 'Call White' and 'Santana'. For this purpose, the foliar spray of low doses of the derivatives at three cultivation moments was performed and several yield variables were determined at crop harvest. All three chitosan compounds increased the performance variables determined respect to the control, depending on the variable, the dose employed and the mass of the derivative evaluated. In most variables determined, the two lowest doses (200 and 325 mg/ha) provoked the highest increments above control. Chitosans also affected distribution of mass per tuber size, particularly; in 'Santana' variety the two lowest doses enhanced the commercial tuber sizes. Among the polymers, CH-1 caused the greatest increases in performance, while, compared to the polymer, CHH provoked higher yields. In conclusion, foliar application at low doses of high molecular weight and hydrolysed chitosan enhanced potato yield between 15-30%.Additional key words: polymer; oligo-chitosan; plant production; tubers.Correspondence should be addressed to Alejandro B. Falcón-Rodríguez: alfalcon@inca.edu.cu; alfalcon04@yahoo.com

Se estima que en el futuro la producción mundial de cacao (Theobroma cacao L.) será insuficiente para su demanda, debido a factores como: pérdida por plagas y enfermedades, árboles envejecidos, rendimientos limitados y efectos del cambio climático. El bioestimulante Quitomax®, cuyo ingrediente bioactivo principal es el quitosano, es un inductor de crecimiento y resistencia, y un antimicrobiano con resultados promisorios en cultivos agrícolas. Sin embargo, debido a que no se ha investigado su efecto sobre el enraizamiento, establecimiento y crecimiento de cacao, el objetivo de este trabajo fue evaluar el efecto del Quitomax® sobre dos variedades comerciales de cacao, en comparación con el producto comercial Raizyner GNS. El diseño experimental fue un arreglo factorial con los dos clones de cacao (A) y tres concentraciones de quitosano (100, 500 y 1000 mg L-1) (B) con tres repeticiones por tratamiento. Como controles se utilizaron plantas no tratadas y plantas tratadas con Raizyner GNS (5000 mg L-1). El bioestimulante Quitomax® promovió un aumento significativo de las variables de crecimiento vegetativo evaluadas de los clones de cacao en comparación con los controles. En relación con la regeneración de las plantas, Quitomax® disminuyó entre un 18% y un 50% los niveles de los esquejes no enraizados. Además, el Quitomax®, favoreció la promoción de crecimiento y bioestimulación de plantas de cacao durante la reproducción clonal por esquejes con resultados incluso mejores que los de algunos otros productos comerciales como Raizyner GNS.