especie y su relación con las condiciones ambientales donde se desarrolla, las cuales pueden ser modificadas por los componentes que integran un sistema agroforestal. Con el objetivo de comparar las variables de intercambio gaseoso en los clones de cacao (Theobroma cacao) TCS01, TCS06, TCS13, TCS19 y CCN51 plantados en un sistema agroforestal con árboles de abarco (Cariniana pyriformis Miers), se evaluó la fotosíntesis neta (A), la conductancia estomática (gs) y la transpiración (E) en una hoja de cacao joven completamente desarrollada en seis plantas de cada uno de los clones, cada hora entre las 08:00 y 17:00 horas (n = 5000) por cinco días. Con los datos de intercambio gaseoso se estimaron las áreas bajo la curva (ABC) para cada variable con base en la sumatoria de las áreas trapezoidales fraccionadas. Los datos de las ABC fueron sometidos a análisis de varianza y los tratamientos comparados por la prueba de medias Tukey (P ≤ 0.05). El clon TCS06 presentó la mayor fotosíntesis neta acumulada con un valor de 137.000 μmol CO2 m-2 día-1, superando a los clones TCS19 y TCS01. Se registraron valores máximos de A = 6.6 μmol CO2 m2 s-1 (TCS06), gs = 0.12 mmol CO2 m-2 s-1 (CCN51) y E = 4.52 mmol H2O m-2 s-1 (CCN51). Los clones TC606 y TCS01 sobresalieron con respecto a TCS13, TCS19 y CCN51. El clon TCS06 presentó la mayor tasa fotosintética en función de la integral diaria del intercambio gaseoso en comparación con TCS19 y TCS13. El CCN51 fue el clon que requirió los mayores valores de radiación fotosintéticamente activa para lograr la máxima actividad fotosintética.

The BBCH (Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) scale is a system that helps producers monitor phenology by employing a uniform methodology across different locations. This study aimed to evaluate the effect of different scion×rootstock combinations on tomato yield and accumulated degree days for each tomato phenological stage. A randomized block design with four repetitions and four treatments was used. Tomato cv. Libertador seedlings were used as a shoot, self-grafted, and over the rootstocks ‘Olimpo’ and ‘Armada’. In addition, there was a non-grafted plant control. There were no significant differences for the accumulated degree days between the treatments since the tomato cultivation required 2,567°Cd-1. The variables, such as plant height, internode number and length, and number of flowers, did not vary significantly between the grafting and non-grafting treatments. The tomato plants grafted over a vigor rootstock produced 39.4 and 20.6% more first category fruits and total fruit yield than non-grafted ones. The heat units necessary to complete the tomato production cycle was not affected by the grafting, and the use of a vigor rootstock had a positive effect on the tomato yield under plastic house conditions.

Grafting as a technique is gaining attention, and the production and demand for grafted vegetable plants have increased worldwide, especially for greenhouse cultivation. This study aimed to evaluate the potential of different scion × rootstock combinations or improving the yield of the tomato crop under greenhouse conditions. For this purpose, a scion of tomato cv. Libertador was grafted on two commercial tomato rootstock (‘Olimpo’ and ‘Armada’) and cultivated in a greenhouse in a randomized complete block experiment design, with four scion-rootstock combinations: vigor and resistance rootstocks, self-grafting and non-grafted plants. The yield and yield components were evaluated (number and weight of the fruits of extra, commercial, and non-commercial quality, weight per cluster, and weight per fruit).  Although vigor rootstocks produce less fresh fruit in the first harvests, from the seventh harvest onwards, the vigor rootstocks outperformed the other treatments in the accumulated yield by producing 37, 22 and 22% more yield, and 60, 30 and 40% higher number of fruits of extra quality in the resistance rootstock, self-grafted, and non-grafted plants. The fruits plants of vigor rootstock, self-grafted and non-grafted above 150 g, tend to have a cylindrical shape; however, fruits in the resistance rootstock tend to be flattened. The use of a vigor rootstock increased the yield of cv. Libertador, regarding the rootstock with resistance characteristics and controls, self-grafted, and non-grafted plants.