Phenological models for implementing management practices in rain-fed avocado orchards1

Abstract

Only a few phenological models have been formulated for rain-fed avocados in warm subhumid environments, and none of them have suggested crop management strategies for improving the trees performance in such conditions. The occurrence and intensity of major phenological events were assessed in 'Hass' and 'Margarida' avocado trees, in order to properly schedule the main crop practices for optimum management of rain-fed orchards in warm subhumid growing environments. Shoot growth, root density, number of open flowers, fruit set and fruit dropping rate were evaluated. For both cultivars, two shoot flushes were observed in September-October (spring) and January-February (summer), while a maximum feeder root growth took place in late August, coinciding with flowering. Two other minor root growth flushes occurred after the onset of summer rains. Both cultivars had only one flowering period, followed by an intense fruitlet dropping. A second minor fruit dropping wave occurred in February (mid-summer), for both cultivars. By determining the extent of each phenological phase in both avocado cultivars, it is possible to schedule applications of fertilizer, mulch and soil amendments, during the root growth flushes, as well as foliar sprays during shoot flushes, in order to maintain an adequate nutritional and sanitary status.

Water status and productivity of 'Hass' avocado trees in response to supplemental irrigation during winter

“…bras., Brasília, v.54, e00237, 2019 DOI: 10.1590/S1678-3921.pab2019.v54.00237 of planting onwards, 30 L h -1 per plant were applied for irrigation; for this, the SuperNet pressure-regulated micro-sprinkler (Netafim Ltd., Tel Aviv, Israel), with a 3.5-m wetted diameter, was installed 1.4 m from each tree trunk. The orchard was managed following the standard cultural traits recommended for avocado trees (Silva et al, 2017).…”

“…Annually, the leaf abscission rate was estimated by the difference between leaf counts on five tagged shoots per tree, in 12 trees per treatment, in July and September. Similarly, the fruit abscission rate was calculated by the difference in fruit counts, also on five tagged shoots per tree, in October and December, after the first and second natural fruit drop period of 'Hass' avocado, respectively (Silva et al, 2017). Fruit yield was annually computed in the harvest date by counting and weighing all fruits picked from each measured tree.…”

“…In the state of São Paulo and in other avocado-growing regions in Brazil, the period of most severe water stress occurs from the beginning of autumn, in April, to the end of winter, in September, coinciding with the stage of floral bud differentiation (Oliveira et al, 2008), flowering, initial fruit set, and spring vegetative flush (Silva et al, 2017) for all the commercially exploited cultivars. During flowering, the evaporative surface of the avocado tree canopy increases by up to 90%, due to the presence of abundant small flowers with a high evaporation rate, leading to an increment of 13 to 15% in the total tree transpiration rate (Whiley et al, 1988).…”

Novas cultivares de abacateiros na região Centro-Oeste do Estado de São Paulo, Brasil

“…Após a segunda queda fisiológica dos frutos, esperada para o início do mês de dezembro (SILVA et al, 2017), acompanhou-se a evolução da maturação dos mesmos em cinco datas a saber: 15/12/2016 e 03/02; 15/02; 22/02 e 01/03/2017 pela determinação da porcentagem de matéria seca. Para tanto, utilizou-se o teste do micro-ondas em que uma amostra composta de 30g da polpa de 10 frutos por cultivar foi submetida à secagem até peso constante.…”

Florescimento de gemas axilares em abacateiros não irrigados cultivados em clima subtropical

“…Nas condições brasileiras, ocorre emissão de dois fluxos vegetativos principais, sendo um na primavera e o outro no verão (OLIVEIRA et al, 2013;SILVA et al, 2017) que são facilmente visualizados por formarem anéis de cicatrização (CHANDERBALI et al, 2013), os quais possuem uma gema terminal e gemas axilares em sua extensão, que devido a sua estrutura anatômica possuem potencial para florescer e tornarem-se produtivas ao longo do ano LOVATT, 1998;SALAZAR-GARCÍA et al, 2006; SALAZAR-GARCÍA, GARNER, LOVATT, 2013).…”