Cacao (Theobroma cacao L.) has traditionally been considered a crop that requires shade, and consequently it is implemented under agroforestry systems (AFs) in order to regulate the level of incident solar radiation. However, optimal shade levels for this tree crop may vary depending on the climate conditions of where it is grown. Here we analyzed the physiological performance of cacao under three different AFs in the Colombian Amazon that differed in solar radiation patterns: high (H_PAR), medium (M_PAR), or low (L_PAR) mean daily incident radiation. The physiological performance was characterized using photosynthetic variables in leaves such as light- and CO₂-response curves, chlorophyll a fluorescence parameters, and total chlorophyll and carotenoid contents, in conjunction with other leaf functional traits. Cacao trees exposed to H_PAR showed an improved physiological performance as compared to those from the other two AFs. Compared to M_PAR and L_PAR, cacao trees in H_PAR doubled the rate of net carbon assimilation and reached higher maximum rates of RuBisCO carboxylation and RuBP regeneration. Moreover, cacao trees in H_PAR presented photoprotection mechanisms that avoided photoinhibition, which was accompanied by a greater non-photochemical quenching coefficient and biochemical and morphological adjustments (low chlorophyll but higher carotenoid contents and low specific leaf area) compared to cacao trees from the other AFs. Overall, our results show that, due to the high cloud cover in the Colombian Amazon, cacao plantations under conditions of sparse shade maximized their carbon use, showing an improved physiological performance as a result of higher photosynthetic rates and energy dissipation mechanisms. If the crop were managed with sparse shade, the paradigm that favors the cultivation of cacao under shade would be called into question in the Colombian Amazon and other regions with similar climatic conditions.

The purple passionfruit plant, Passifloraedulis Sims, ranks second in fruit exportation in Colombia, and its main destination is the European market. However, its production is affected by several diseases, including fusariosis. This paper presents the histopathological features of different tissues affected by the pathogens Fusarium oxysporum and Fusarium solani. Both microorganisms produce similar responses on the plant: colonization of xylem vessels by hyphae and microconidia, hypertrophy and hyperplasia of the cambium, xylem and phloem; destruction of xylem fibers and amyloplasts in parenchymatous cells; and production of gels by the plant. However, there are differences in the colonization mechanism, F. solani penetrates and is concentrated especially at the collar zone, while F. oxysporum penetrates the roots and moves through the vascular system to colonize the plant.

We present a typology of cacao agroforest systems in Colombian Amazonia. These systems had yet to be described in the literature, especially their potential in terms of biodiversity conservation. The systems studied are located in a post-conflict area, and a deforestation front in Colombian Amazonia. Cacao cropping systems are of key importance in Colombia: cacao plays a prime role in post conflict resolution, as cacao is a legal crop to replace illegal crops; cacao agroforests are expected to be a sustainable practice, promoting forest-friendly land use. We worked in 50 x 2000 m² agroforest plots, in Colombian Amazonia. A cluster analysis was used to build a typology based on 28 variables characterised in each plot, and related to diversity, composition, spatial structure and light availability for the cacao trees. We included variables related to light availability to evaluate the amount of transmitted radiation to the cacao trees in each type, and its suitability for cacao ecophysiological development. We identified 4 types of cacao agroforests based on differences concerning tree species diversity and the impact of canopy spatial structure on light availability for the cacao trees in the understorey. We found 127 tree species in the dataset, with some exclusive species in each type. We also found that 3 out of the 4 types identified displayed an erosion of tree species diversity. This reduction in shade tree species may have been linked to the desire to reduce shade, but we also found that all the types described were compatible with good ecophysiological development of the cacao trees. Cacao agroforest systems may actually be achieving biodiversity conservation goals in Colombian Amazonia. One challenging prospect will be to monitor and encourage the conservation of tree species diversity in cacao agroforest systems during the development of these cropping systems, as a form of forest-friendly management enhancing sustainable peace building in Colombia.

In order to review the literature on the ecophysiology of the cape gooseberry, it was found that this typical Andean plant, in Colombia adapts to a wide altitudinal range of the tropical cold climate, that is, between 1,800 and 2,800 meters above sea level (m a.s.l.), with optimal medium temperatures between 13 and 16°C and base (minimum) temperatures for stem and fruit growth are relatively low, 6.3 and 1.9°C, respectively, however it does not withstand temperatures <0°C. Likewise, the Andean conditions of the tropics such as high solar radiation and day lengths <12 hours, rather short, favor the flower initiation. 1,500-2,000 hours year-1 of direct sunshine are the most favorable for the size, quality and ripening of the fruit. Under field conditions in Bogota, a photosynthesis rate of A = 10.545 μmol CO2 m-2 s-1 and light compensation point Ic = 13.645 μmol photons m-2 s-1 was measured. As a plant with an indeterminate growth habit, a constant supply of water is essential, while high amounts or heavy rains after a dry season cause cracking of the fruits, just as the plant does not tolerate waterlogging for more than 4 days. Cape gooseberry is classified as moderately tolerant to salinity and 30 mMol NaCl curiously promote growth, having mechanisms, such as increased antioxidant activity, to protect against saline conditions.