23 Jun 2022
Foliar Fertilizer

Properly Timing Foliar-applied Fertilizers Increases Efficacy: A Review and Update on Timing Foliar Nutrient Applications to Citrus and Avocado

Foliar fertilization efficiently meets the nutrient demand of tree fruit crops during periods when soil conditions (low or high temperatures, low or excess soil moisture, pH, salinity) render soil-applied fertilizers ineffective, when nutrients (e.g., phosphate, potassium, and trace elements) become fixed in the soil, and when tree nutrient demand is high. Applying nutrients directly to leaves ensures that the metabolic machinery of the tree is not compromised by low availability of an essential nutrient. It should be noted that phloem mobile nutrients applied to the foliage are translocated to all tree parts, even feeder roots.

READ MORE

25 May 2022
Orange Blossom

Influence of Temperature and Photoperiod on Flower Induction and Inflorescence Development in Sweet Orange.

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.

READ MORE

25 May 2022
Citrus Tree Stresses

Citrus Tree Stresses: Effects on Growth and Yield

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.

READ MORE

25 May 2022
Young Clementine

Seasonal Fe Uptake of Young Citrus Trees and Its Contribution to the Development of New Organs

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.

READ MORE

25 May 2022
Carotenoid Biosynthesis

Carotenoid Biosynthesis and their Regulation in Citrus Fruits

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.

READ MORE

22 Apr 2022
Orange Tree

Salinity Interactions with Other Abiotic and Biotic Stresses in Citrus

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.

READ MORE

22 Apr 2022
Citrus Harvest EC

The synthetic auxin 3,5,6-TPA stimulates carbohydrate accumulation and growth in citrus fruit

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.

READ MORE

22 Apr 2022
Citrus Rind

Preharvest Foliar Sprays of Prohexadione–calcium, a Gibberellinbiosynthesis Inhibitor, Induce Chlorophyll Degradation and Carotenoid Synthesis in Citrus Rinds

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.

READ MORE