Fruit size is a key parameter for quality and increases the profitability for export markets in citrus production in Turkey. Fruit size can be enhanced by several techniques such as girdling and thinning. Various plant growth regulators are known to affect the growth and size of citrus fruit. Thus the effects of synthetic auxin applications (2,4-DP and 3,5,6-TPA) at different physiological periods, girdling practices, pruning practices, foliar application of potassium and various combinations of these practices on the fruit size and yield, fruit retention rate, and leaf chlorophyll concentration and fluorescence of Star Ruby grapefruit cultivar were investigated.
The effect of combined deficit irrigation and summer trunk girdling on the internal fruit quality of ‘Marisol’ Clementines
The influence of girdling, deficit irrigation, and a combination of girdling and deficit irrigation on fruit quality of ‘Marisol’ Clementines was investigated over two seasons, 1998 and 1999, at two different sites in South Africa. Girdling increased the total soluble solids (TSS) by 2-10%,however, the effect was not always significant. There were no trends observed for external fruit colour, fruit diameter, juice content (%), titratable acidity (TA) and TSS:TA ratios due to girdling.
Current citriculture is threatened by climate change. The increase in temperature, together with other adverse climate phenomena, is modifying the environmental conditions in the regions where citrus varieties are currently being developed. The detrimental effects of these adverse environmental factors on citrus physiology and production, such as drought or augmented soil salinity, will likely increase because of elevated temperatures, which will jeopardise crop production and, in extreme cases, even plant survival.
Sustainability in Brazilian Citriculture: Three Decades of Successful Biological Control of Insect Pests
Citrus insect pests has grown worldwide, concerning entomologists and farmers especially because of the high demand for food that makes it to our tables. The use of pesticides brought several issues, such as the negative impacts on the human health, pollution, and insect resistance. In this context, more environmentally-friendly strategies have been demanded by governments and consumers. In this review, we present three remarkable examples of pest management in Brazil that involved many researchers from different expertise areas to develop more sustainable strategies to reduce the damages to citrus production.
Effects of NAA and GA3 Sprays on Fruit Size and the Incidence of Creasing of ‘Washington’ Navel Orange
‘Washington’ navel orange [Citrus sinensis (L.) Osb.] orchards in Israel suffer from creasing – a physiological disorder of the fruit, leaving the fruit unsuitable for the fresh fruit market. Many ‘Washington’ navel orchards tend to bear small size fruit with low market value. This paper presents two experiments, in which the effects of naphthaleneacetic acid (NAA, 300 mg·L-1) on yield, fruit size, fruit quality and the incidence of creasing of ‘Washington’ navel orange were examined. The NAA effects were compared to those of gibberellic acid (GA3, 20 mg·L-1) – the common treatment for creasing reduction. In the first experiment, 36% of the fruit of the control trees suffered from severe creasing. The NAA sprays in May (at 18-mm fruitlet diameter) and in June (at 30-mm fruitlet diameter) reduced the incidence of creasing to 9 and 6% respectively, while the GA3 spray at August reduced the incidence of creasing to 17% of the fruit.
CGA’s Justin Chadwick said cold treatment requirement is unnecessary, unjustified and disproportionate.
The South African citrus industry is scrambling to avert disruptions in its citrus exports to the European Union due to changes in regulations governing the importation of oranges into the EU.
The new regulations, which deal specifically with orange imports from South Africa and other sub-Saharan countries, were published in the Official Journal of the European Union on Tuesday and will come into force today.
This paper describes the physiological effects of abscisic acid (ABA) and 100 mM NaCl on citrus plants. Water potential, leaf abscission, ethylene production, photosynthetic rate, stomatal conductance, and chloride accumulation in roots and leaves were measured in plants of Salustiana scion [Citrus sinensis (L) Osbeck] grafted onto Carrizo citrange (Citrus sinensis [L.] Osbeck · Poncirus trifoliata [L.] Raf) rootstock. Plants under salt stress accumulated high amounts of chloride, increased ethylene production, and induced leaf abscission. Stomatal conductance and photosynthetic rates rapidly dropped after salinization.
The application of the synthetic auxin 3,5,6-TPA at the cell enlargement stage increased hexoses in developing fruit from foliated and fully defoliated plants of Satsuma mandarin, cv. ‘Okitsu’ (Citrus unshiu Marc.). Although the sucrose concentrations also increased, in general the differences were not statistically significant. The plant growth regulator reduced fruit abscission in defoliated trees while it stimulated fruit growth in the foliated ones.