The avocado cv. Hass requires a suitable rootstock for optimal development under water stress. This study evaluated the performance of two avocado rootstocks (ANRR88 and ANGI52) grafted onto cv. Hass under four water stress conditions, 50% and 25% deficit, and 50% and 25% excess during the nursery stage. Plant height, leaf area (LA), dry matter (DM), and Carbon (OC) content in the roots, stems, and leaves were measured. Root traits were evaluated using digital imaging, and three vegetation indices (NDVI, CI_RE, and MTCI) were used to quantify stress. The results showed that genotype significantly influenced the response to water stress. ANRR88 exhibited adaptation to moderate to high water deficits. ANGI52 adapted better to both water deficit and excess, and showed greater root exploration. LA and DM reductions of up to 60% were observed in ANRR88, suggesting a higher sensitivity to extreme changes in water availability. More than 90% of the total OC accumulation was observed in the stem and roots. The NDVI and the MTCI quantified the presence and levels of stress applied, and the 720 nm band provided high precision and speed for detecting stress. These insights are crucial for selecting rootstocks that ensure optimal performance under varying water availability, enhancing productivity and sustainability.

The objective of this work was to determine the effect of planting densities on the yield and quality of 'Hass' avocado (Persea americana) in the department of Antioquia, Colombia. The experimental design was randomized complete blocks with three replicates. The treatments were six plant densities (204, 278, 333, 400, 625, and 816 trees per hectare) with five harvest seasons, and each experimental unit consisted of six nine-year-old trees. The highest fruit yield is obtained at 333 and 400 trees per hectare. The main harvest represents 70% (18 Mg ha^-1) of the annual production, whereas the secondary (mitaca) harvest represents 30% (5.25 Mg ha^-1). Yield per tree and number of avocado fruits per tree are negatively affected by the increase in planting densities. In addition, fruit quality parameters show better results at intermediate planting densities of 333 and 400 trees per hectare, with the highest ratios of mesocarp and the lowest of seed, both in fresh and dry weight.

There is limited information in Colombia on the effect of rootstock compatibility on the amount and concentration of nutrients in avocado cv. Hass. This study aimed to determine the effect of rootstock/scion compatibility on fruit and leaf nutritional concentration. This experiment was developed in 9-year-old commercial avocado ‘Hass’ orchards in three locations with a moderately cold climate in Colombia (Rionegro, El Peñol, and Anserma). The scion cv. Hass was grafted on rootstocks with an Antillean origin. 15 trees were selected and marked in each orchard and location, and 25 fruits per tree and per treatment were taken at random (compatible and incompatible grafting). Subsequently, the fresh and dry weight of the skin (epicarp), the pulp (mesocarp), seed, and the seedcoat were obtained. The concentration of major and minor elements was analyzed in each tissue. There was no significant effect on the concentration of nutrients in the fruits from trees with and without compatibility between rootstock and scion. Statistical differences were observed at three locations in the concentration of nutrients in the different parts of the fruit. The nutrient with the highest concentration in the four fruit tissues was K, followed by N. The seed coat had the highest concentration of nutrients for all locations. The embryo had the lowest concentration of the major elements, such as N, K, Ca, Mg, S, and P. The order of the concentration in the fruit tissues was: K> N> Mg> P> Ca> S> Fe> B> Zn > Mn. The compatibility did not show significant differences between the leaf mineral content, nor did it affect the nutrient balances for each element at the foliar level.

The rootstock/scion morphological alterations are one of the limitations in the use of grafting, which has been defined as an incompatibility between these two tissues. However the effect of rootstock-scion interactions on reproductive potential, fruit set, yield efficiency, and avocado fruit quality characteristics are complex and poorly understood. This research aimed to evaluate the fruit growth of avocado cv. Hass in trees with incompatibilities between the rootstock and the graft in the main producing regions in Colombia. The split-plot design with a locality-blocking factor was used. The main plot corresponded to the compatibility and harvest factor, and the subplots to the age of fruit development. The statistical analysis consisted of a mixed linear model for the variables of respiratory rate and morphological growth of the fruit, performing a significant multiple difference test using the adjustment for multiplicity by family through Holm’s correction. The compatibility treatment and the harvest season did not affect the fruit respiratory rate nor the variables of growth and development of cv. Hass. However, the age of development significantly affected both the respiratory rate and the variables of fruit growth.

In Colombia, the evidence of rootstock/scion incompatibility in avocado cv. Hass graft union has been increasing, generating concern among farmers. The objective was to evaluate the photosynthetic response of the avocado trees due to rootstock/scion compatibility in three locations. A split plots design with a blocking factor per locality was used. The main plot corresponded to the type of graft union (compatible and incompatible) and the subplots to leaf age during the 2020 and 2021 seasons. Climatic (water balance) and gas exchange variables (photosynthesis, transpiration, stomatal conductance, leaf temperature, and efficiency in instantaneous water use) were measured. The results indicate that the photosynthetic performance was not affected when the water balance was negative. Compatibility did not significantly affect gas exchange variables (A, gs, E, Tl, and WUEi) during the main and secondary harvest period. The leaf age/harvest period interaction shows that during the first months of leaf development, A, g_s, E, and Tl are greater and are detrimental over time. It is concluded that the rootstock/scion compatibility does not significantly modify the capacity to assimilate CO₂. At the same time, the variation in avocado photosynthetic activity depends on the age of the leaves and the harvest season.

This study aimed to evaluate the influence of botanical composition calibration on the accuracy of undisturbed sward height and comparative yield method (CYM) techniques for herbage mass estimation...