24 May 2024
Citrus flower

Demonstration of a Change in Nitrogen Metabolism Influencing Flower Initiation in Citrus

Changes in the leaf NH3-NH4 + content were monitored during floral induction in Citrus. Five-year-old rooted cuttings of ‘Washington’ navel orange (Citrus sinensis) were induced to flower by subjecting the trees to 8 weeks of low temperature, 8-h day (500 μE m−2 s−1) at 15–18°C/16-h night at 10–13°C and by transferring them afterwards to 12-h day (500 μE m−2 s−1) at 24°C/12-h night at 19°C. Maximum bloom occurred 4 weeks after the transfer to the warmer temperature. The number of flowers and the NH3–NH4 + content of leaves increased significantly (p < 0.05 and P < 0.01, respectively) with the length of the low temperature treatment. Sixteen-year-old ‘Frost Lisbon’ lemon trees (Citrus limon) on ‘Troyer’ citrange rootstocks (C. sinensis × Poncirus trifoliata) under commercial production were subjected to water-deficit stress of increasing severity.

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24 Jul 2023

Timing Citrus and Avocado Foliar Nutrient Applications to Increase Fruit Set and Size

The goal of this research was to identify the role essential nutrients play in the physiology of tree crops, and then to apply the nutrient as a foliar fertilizer to stimulate a specific metabolic process at phenological stages when nutrient demand is high. This approach has proven successful. A single winter prebloom foliar application of nitrogen as low-biuret urea [0.16 kg N/tree (0.35 lb N/tree)] to 30-year-old ‘Washington’ navel orange (Citrus sinensis L. Osbeck) trees during flower initiation significantly increased yield and fruit number per tree for each of 3 consecutive years (P ≤ 0.05). The number of commercially valuable large size fruit also increased significantly with yield increases (r² = 0.88).

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24 Aug 2021

The influence of nitrogen concentration and ammonium/nitrate ratio on N-uptake, mineral composition and yield of citrus

In  short-term   water  culture  experiments  with  different  15N  labeled  ammonium  or  nitrate  concen trations,  citrus seedlings absorbed  NH; at  a higher  rate  than  No;. Maximum NO; uptake  by the whole plant  occurred  at 120 mg L – 1  NO;-N, whereas NH; absorption  was saturated  at 240 mg L –  1 NH;-N. 15NH; accumulated in roots and to a lesser degree in both leaves and stems. However,  15NO; was mostly partitioned  between leaves and roots.

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25 Mar 2021
Citrus and Avocado

Timing Citrus and Avocado Foliar Nutrient Applications to Increase Fruit Set and Size

The goal of this research was to identify the role essential nutrients play in the physiology of tree crops, and then to apply the nutrient as a foliar fertilizer to stimulate a specific metabolic process at phenological stages when nutrient demand is high. This approach has proven successful. A single winter prebloom foliar application of nitrogen as low-biuret urea [0.16 kg N/tree (0.35 lb N/tree)] to 30-year-old ‘Washington’ navel orange (Citrus sinensis L. Osbeck) trees during flower initiation significantly increased yield and fruit number per tree for each of 3 consecutive years (P ≤ 0.05).

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