Plant Health Archives

2018 California

Evaluation of leaf carbon isotopes and functional traits in avocado reveals water-use efficient cultivars

Authors: Acosta-Rangel, A.; Ávila-Lovera, E.; De Guzman, M.; Torres, L.; Haro, R.; Arpaia, M.L.; Focht, E.; Santiago, L.

Plant water-use efficiency (WUE) describes the ratio of carbon gain to water loss during photosynthesis. It has been shown that WUE varies among crop genotypes, and crops with high WUE can increase agricultural production in the face of finite water supply. We used measures of leaf carbon isotopic composition to compare WUE among 24 cultivars of Persea americana Mill (avocado) to determine genotypic variability in WUE, identify potentially efficient cultivars, and to better understand how breeding

Read full article

2021 Chile

Evaluation of aerial and root plant growth behavior, water and nutrient use efficiency and carbohydrate dynamics for Hass avocado grown in a soilless and protected growing system

Authors: Beyer, C.; Cuneo, I.; Alvaro, J.; Pedreschi, R.

Avocado production is nowadays questioned worldwide and at risk due to climate change and the high water footprint of this crop. Thus, there is need for the development or adoption of new strategies such as alternative production systems. In this study, Hass avocado plants grafted on two rootstocks (Mexicola -seed propagated and Dusa® - vegetative-propagated and referred as clonal) were grown in a greenhouse and substrate (coir growth container, 55 L of volume and 500 × 480 mm, H X W) culture

Read full article

2008 Chile

Soil air content effects on the water status of avocado trees

Authors: Ferreyra, R.; Maldonado, P.; Celedon, J.; Gil, P. M.; Torres, A.; Selles, G.

Avocado trees evolved in Andisoils, which are considered the optimum type of soils for tree growth due to their physical properties; mainly low bulk density (0.5 - 0.8 g cm(-3)) and high macro porosity (similar to 46%). In Chile, avocado orchards are mostly located in fine textured soils, with bulk densities between 1.3 and 1.5 g cm(-3) and macro porosities close to 15%. Due to this fact, there are severe problems of poor root aeration which, in part, are responsible for the low production levels

Read full article

2017 Greece

Growth, photosynthetic performance and antioxidative response of ‘Hass’ and ‘Fuerte’ avocado (Persea americana Mill.) plants grown under high soil moisture

Authors: Doupis, G.; Kavroulakis, N.; Psarras, G.; Papadakis, I.E.

‘Hass’ and ‘Fuerte’ avocado plants were grown under well-watered or waterlogged conditions. Results indicated significant effects on the majority of the allometric parameters in waterlogged plants, with ‘Fuerte’ displaying a more pronounced growth inhibition. Waterlogged conditions caused a progressive and simultaneous decline in net photosynthetic rate and stomatal conductance, earlier in ‘Fuerte’ than in ‘Hass’. Maximal potential quantum yield of PSII was unaffected by the soil

Read full article

1995 South Africa

Bioenergetics, respiration cost and water relations of developing avocado fruit

Authors: Blanke, M.M.; Whiley, A.W.

Avocado fruit of cultivars with different susceptibility to physiological fruit disorders were examined in situ for respiration, stomatal conductance, transpiration and xylem water potential. Therein, attached fruit of cv. Fuerte (susceptible to mesocarp discolouration) were compared with Hass (susceptible to small fruit) over the 3-month period from anthesis until the fruit reached 60 g fresh matter:1. Avocado fruit respired more CO2 in the dark than in the light due to fruit photosynthesis. Respiration

Read full article

2013 Multiple

The water relations and irrigation requirements of avocado (persea americana mill.): a review

Authors: Carr, M.K.V.

The results of research on the water relations and irrigation need of avocado are collated and reviewed in an attempt to link fundamental studies on crop physiology to irrigation practices. Background information is given on the centre of origin (Mexico and Central America) and the three distinct ecological areas where avocados are grown commercially: (1) Cool, semi-arid climates with winter-dominant rainfall (e.g. Southern California, Chile, Israel); (2) Humid, subtropical climates with summer-dominant rainfall (e.g. eastern Australia, Mexico, South Africa); and (3) Tropical or semi-tropical climates also with summer-dominant rainfall (e.g. Brazil, Florida and Indonesia). Most of the research reported has been done in Australia, California, Israel and South Africa. There are three ecological races that are given varietal status within the species: Persea americana var. drymifolia (Mexican race), P. americana var. guatemalensis (Guatemalan race) and P. americana var. americana (Antillean, West Indian or Lowland race). Interracial crossing has taken place. This paper summarises the effects of water deficits on the development processes of the crop and then reviews plant-water relations, crop water requirements, water productivity and irrigation systems. Shoot growth in mature trees is synchronised into flushes. Flower initiation occurs in the autumn, with flowering in late winter and spring. Flowers form on the ends of the branches. A large heavily flowering tree may have over a million flowers, but only produce 200-300 fruits. Fruit load adjustment occurs by shedding during the first three to four weeks after fruit set and again in early summer. Water deficits during critical stages of fruit ontogeny have been linked to fruit disorders such as ring-neck. Reproductive growth is very resistant to water stress (compared with vegetative growth). Avocado is conventionally considered to be shallow rooted, although roots extend to depths greater than 1.5 m. The majority of feeder roots are found in the top 0.60 m of soil and root extension can continue throughout the year. Leaves develop a waxy cuticle on both surfaces, which is interrupted by stomata on the abaxial surface (350-510 mm(-2)), many of which are blocked by wax. Stomata are also present on the sepals and petals at low densities (and on young fruit). During flowering, the canopy surface area available for water loss is considerably increased. Stomatal closure is an early indicator of water stress, which together with associated changes in leaf anatomy, restricts CO2 diffusion. There have only been a few attempts to measure the actual water use of avocado trees. In Mediterranean-type climates, peak rates of water use (in summer) appear to be between 3 and 5 mm d(-1). For mature trees, the crop coefficient (K-c) is usually within the range 0.4-0.6. The best estimate of water productivity is between 1 and 2 kg fruit m(-3). Soil flooding and the resultant reduction in oxygen level can damage roots even in the absence of root rot. Avocado is particularly sensitive to salinity, notably that caused by chloride ions. Rootstocks vary in their sensitivity. Both drip and under-tree microsprinklers have been/are successfully used to irrigate avocado trees. Mulching of young trees is a recommended water conservation measure and has other benefits. A large proportion of the research reviewed has been published in the 'grey' literature as conference papers and annual reports.Sometimes, this is at the expense of reporting the science on which the recommendations are based in peer-reviewed papers. The pressures on irrigators to improve water productivity are considered.

Read full article