This week, the European Union’s (EU) Standing Committee on Plant, Animal, Food and Feed (SCOPAFF) will discuss and, possibly vote on, new and arguably misinformed regulations on False Coddling Moth (FCM) which pose a major threat to Southern African orange exports.
At low temperature (15° C.day/5° C.night) flowering of sweet orange cuttings was not photoperiodically controlled, occurring at 16-, 12-, and 8-hour photoperiods. When plants were transferred, after varying periods of low temperature (15°/8° C.) to warm conditions (30°/25° C.), growth of the buds commenced within a few days of transfer. Flowering response to length of the cold treatment appeared to be quantitative.
Although Florida is known for its plentiful sunshine and rainfall, commercial citrus can experience stress at certain times of the year whenever growth conditions are not optimal. For example, drought stress can occur whenever soil water is not adequate or whenever the evaporative demand of the air is high. Drought is one of the most formidable stresses. It alters a tree’s ability to take up nutrients from soil and changes the way the tree produces roots, shoots, leaves and fruit. To strive for consistently high commercial yields, grove managers must incorporate strategies to minimize the negative effects of drought.
This work quantifies Fe uptake in young citrus trees, its partitioning among plant compartments, and the contribution of the Fe absorbed from fertilizer to the development of new tissues. A soil pot experiment was conducted using 4-year-old clementine trees (Citrus clementina Hort ex Tan), and a dose of 240 mg Fe was applied by labeled fertilizer (92% atom 57Fe excess). Plants were uprooted at five different phenologic states: end of flowering (May 15), end of fruit setting and fruit drop (July 1), two fruit growing moments (August 1 and October 15), and at complete fruit maturity (December 10). The Fe accumulated in the root system exceeded 90% of the total Fe content in the plant. All organs progressively enriched with 57Fe (8.5–15.5% and 7.4–9.9% for young and old organs, respectively). Reproductive ones reached the highest increase (111% between May and October). 57Fe enrichment from woody organs reflects an increasing gradient to sink organs.
Carotenoids are the main pigments responsible for the attractive color of the peel and pulp of citrus fruits and greatly contribute to their nutritional and antioxidant value. Fruits of different Citrus species display a broad array of color singularities and in many cultivars the peel and the pulp also exhibit different color, envisaging specie- and tissue- specific regulation of the carotenoid content and composition.
Multiple stresses almost always have synergistic effects on plants. In citrus, there are direct and indirect interactions between salinity and other physical abiotic stresses like poor soil drainage, drought, irradiance, leaf temperature, and atmospheric evaporative demand. In addition, salinity interacts with biotic pests and diseases including root rot (Phytophthora spp.), nematodes, and mycorrhizae.
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.
Rind color is an important cosmetic preference of consumers when purchasing citrus fruit. As citrus fruit mature, a decrease in chlorophyll concentration unmasks the presence of carotenoid pigments followed by further synthesis of carotenoids, resulting in the first appearance of the characteristic orange color of mandarins and sweet oranges.
Justin Chadwick, CEO of the CGA, shared his thoughts on the Russia-Ukraine conflict, and the impact it could have on the citrus industry.
“The Citrus Growers’ Association of Southern Africa (CGA) is working closely with exporters, government and other stakeholders across the citrus value chain to mitigate the impact that the Russian invasion of Ukraine has had on our local citrus growers and exporters. This includes fruit destined for Russia being blocked, delays in fruit getting to the market as well as further increases in input costs for growers and exporters as a result of the conflict.
Salinity is an obstacle to citriculture worldwide, and is a concern in arid, semiarid, and coastal regions. In the current study, we irrigated one-year-old ‘Valencia’ trees budded onto Kuharske rootstock with 60 mM sodium chloride (NaCl) solution for ten weeks. Subsequently, these trees were sprayed with 50, 75, and 100 mM SA or MeJA to determine whether these phytohormones could alleviate the detrimental effects of salinity. READ MORE