Respuesta fenológica de dos cultivares de maní (Arachis hypogaea l.) al fotoperíodo

El mani (Arachis hypogaea L.), responde al fotoperiodo en post-floracion como de dia corto (DC), donde DC estimulan la particion de biomasa a frutos y granos. Estos efectos son genotipos especificos y modificados por la temperatura. El objetivo fue determinar el efecto del fotoperiodo en la duracion de las etapas fenologicas en dos cultivares de mani. El estudio se realizo en 2009/10 y 2010/11, en el campo experimental, UNRC. El diseno fue en bloques al azar con un arreglo de parcelas divididas. El factor principal fue la fecha de siembra (FS) (3): temprana, media y tardia. El factor secundario el cultivar (2): Utre (ciclo intermedio-corto) y Granoleico (ciclo largo). Se realizo una determinacion fenologica con una frecuencia de 10 dias y la duracion de las etapas se calculo en tiempo termico (TT). Se ajustaron funciones de TT para las distintas etapas y el fotoperiodo promedio. Se realizaron pruebas de homogeneidad de pendientes, y la respuesta del fotoperiodo se caracterizo mediante un modelo lineal-plateau. El retraso de la FS produjo un acortamiento del TT durante el periodo de llenado de granos (R5-R8), y se detecto una respuesta de la duracion de esta etapa al fotoperiodo de tipo dia corto-cuantitativa. Ambos cultivares fueron sensibles, con diferencias entre ellos en los parametros de respuesta. Granoleico mostro mayor sensibilidad (224,8°Cd h-1), menor umbral fotoperiodico (12,74 h) y precocidad intrinseca (294°Cd); en comparacion con Utre con 188,5°Cd h-1, 13,13 h, y 439°Cd, respectivamente. Abstract Peanut (Arachis hypogaea L.), responds to the photoperiod in post-flowering as a short-day species (SD), where SD stimulates dry matter partition to pods and grains. These effects are genotypes-specific and modified by temperature. The objective was to determine the effect of the photoperiod on crop stages duration in two cultivars of peanuts. The study was conducted in 2009/10 and 2010/11, in the Experimental Field, UNRC. The design was a randomized blocks with a split plots array. The main factor was sowing date (SD) (3): early, middle and late. The secondary factor was the cultivar (2): Utre (short-intermediate cycle) and Granoleico (long cycle). The crop was conducted without water restrictions, and weeds, insects and diseases were controlled. A phenological determination was made in a 10-days frequency and the duration of stages were calculated in thermal time (TT). TT functions were fitted for the different stages and the average photoperiod to which the crop was exposed. Slopes homogeneity tests were performed, and the photoperiod response was characterized through a linear plateau model. The FS delay produced a shortening of TT  during pod and grain filling period (R5-R8), and a response of the duration of this stage to the quantitative short day type photoperiod was detected. Both cultivars were sensitive, with differences among them in the response parameters. Granoleico showed higher sensitivity (224,8°Cd h-1), lower photoperiodic threshold (12,74 h) and intrinsic earliness (294°Cd); compared to Utre with 188,5°Cd h-1, 13,13 h, and 439°Cd, respectively. These responses were observed under suboptimal temperature conditions.