Potassium Extraction by Different Avocado Cultivars
The avocado producing area of Mexico involves thousands of small farmers and area of approximately 100,000 hectares. The crop is grown in different systems and includes several regions and cultivars. However, the State of Michoacan, in west Mexico concentrates most of the area and cultivation systems. This short report presents information on the differences in fresh weight and fruit potassium (K) uptake in four avocado commercial cultivars.
Research was conducted in “Booth-8”, “Choquette”, “Hall” and “Hass” avocado cultivars, grown at four commercial orchards located in the State of Nayarit, in the west of Mexico. Five avocado fruits (physiological ripe and of dominant size) were harvested from twenty trees of each cultivar. A total of 100 fruits per cultivar were analyzed. Chemical analyses were perform by a certified commercial laboratory using standard methods approved by the Mexican Soil Science Society. As shown in Table 1, K content in the fruit is the highest compared to all mineral nutrients analyzed for all four cultivars. Even nitrogen (N) content is lower than K content in the fruit and represented from 60 to 80% of the K values found in all cultivars.
When a comparison of the total fresh weight of fruit was made, “Hass” avocado (239 g) could be considered to be a small fruit compared to the “Booth-7” (405 g), “Hall” (525 g) and “Choquette” (879 g) cultivars, (Fig. 1). However, oil content and dry weight of Hass avocado has been reported to be higher than all other cultivars. If the comparison is based upon fresh weight and same yields (20 t/ha), “Hass” fruit has the highest K content, with at least 55% more, compared to all other cultivars (Table 1). Nutrient content ranking for all four avocado cultivars was: K > N > phosphorus (P) > sulfur (S) > magnesium (M) > calcium (Ca). It is important to evaluate the relative importance of all nutrients and their removal by the fruit when a balanced fertilization program is design.
Table 1. Mineral nutrient content in avocado fruit from four different commercial cultivars.
Field data was done by Dr. Samuel Salazar in 1998-1999.
This research project was partially funded by INPOFOS.