Identification of the Appropriate Leaf Sampling Period for Nutrient Analysis in ‘Hass’ Avocado

Abstract

<jats:p>This research was carried out from 2004 to 2005 in two commercial ‘Hass’ avocado orchards cultivated under rainfed conditions in a hot subhumid climate of the state of Nayarit, Mexico. The objectives of this study were to: 1) establish the patterns in nutrient concentrations during the lifespan of winter and summer vegetative flush leaves; and 2) validate a methodology based on mathematical functions to identify the appropriate period for leaf sampling to diagnose plant nutrition in avocado considering its two major vegetative flushes. Leaf samples were taken monthly for each vegetative flush, starting when leaf length was 5 cm or greater and concluding at leaf abscission. Starting at vegetative budbreak, winter and summer leaves lived 12.5 and 7.8 months, respectively. Summer flush leaves grew faster and attained greater length than winter leaves. A mathematical model based on the concentration of macro- and micronutrients through the lifespan of avocado leaves was evaluated. This model was used to determine the period when nutrient concentrations became stable and, consequently, to identify the proper leaf sampling period. For the ‘Hass’ avocado in Nayarit, the period for sampling winter flush leaves corresponded to 6.6- to 7.9-month-old leaves (4 Sept. to 13 Oct.). For summer leaves the optimum period was shorter and occurred when leaves were 3.9 to 4.9 months old (5 Dec. to 5 Jan.). The procedure and sampling time obtained here should be tested in other regions.</jats:p>

Macronutrient dynamics in avocado (Persea americana Mill.) ‘Hass’ under the central peruvian coast conditions

“…High N and low Ca levels in the exocarp of avocado could be associated with anthracnose and lower postharvest quality. Salazar-García et al (2015) mentioned that variations in Ca concentrations in leaves of vegetative shoots are very similar, and these also increase with age. Lahav et al (1990) found that Ca in leaves of the previous years was higher than those of summer leaves.…”

“…In our case, the concentration of 2.7 % was obtained. Silber et al (2018) mentioned thattotal N in 'Hass' fruits increase from the beginning of inflorescence until fruit set, and then decrease during fruit development (Salazar-García et al, 2015). After fruit set, in new fruit development, Lovatt (1995) and Salvo (2017) declared that the highest N demands occur due to the competition between fruit and new shoot formation; however, if there are reserves in the soil and small branches, fertilization is not required (Lahav et al, 1990;Rosecrance et al, 2003).…”

Seasonal nutrient content variation in avocado leaves of ‘Geada’, ‘Fortuna’ and ‘Quintal’ genotypes

“…Therefore, it would not be recommended to sample leaves for foliar diagnosis purposes in periods within or close to this phenological phase. According to Salazar-García et al (2015), the most suitable period for collecting leaves for foliar diagnosis is the one where the levels of the nutrients of interest are more stable.…”

“…However, there are indications that the leaf nutrient content of fruit plants varies depending on the time of year and phenology (LEONEL et al, 2012;CRUZ et al, 2019), which must occur at different times for different genotypes and different edaphoclimatic conditions. Studies carried out to identify the best time for leaf sampling in various avocado cultivars suggest that leaf collection should be carried out in the period of greater nutrient content stability (SALAZAR-GARCÍA et al, 2015).…”

Nitrogen uptake and macronutrients distribution in mango trees (cv. Keitt) under three N fertigation treatments

“…Leaf-N status is frequently used for fertilization-management decisions in the mango industry (Hundal et al, 2005; Raghupathi et al, 2005; Raj and Rao, 2006; Pinto et al, 2007; Kumar et al, 2015; Salazar-Garcia et al, 2018). However, leaves may remain attached for several years on mango trees (Pinto et al, 2007), and the N-fertilization thresholds may vary with factors such as seasonal aspects (Urban et al, 2006), leaf age, rootstock, physiological and phenological status, distance from the inflorescences or fruit (Urban et al, 2004b; Pinto et al, 2007) and fruit:leaf ratio (Urban and Léchaudel, 2005).…”