Nitrogen Nutrition of Containerized Citrus Nursery Plants

Abstract

<jats:p>Experiments were conducted with `Hamlin' orange [<jats:italic>Citrus sinensis</jats:italic> (L.) Osb.] budded on Cleopatra mandarin (<jats:italic>Citrus reticulata</jats:italic> Blanco) or Carrizo citrange [<jats:italic>Citrus sinensis</jats:italic> (L.) Osb. × <jats:italic>Poncirus trifoliata</jats:italic> (L.) Raf.] seedling rootstocks to determine minimum container solution N concentrations required for optimum growth and fertilizer uptake efficiency at various growth stages. Plants were fertigated daily with 1 liter of N solution at either 0, 12.5, 25, 50, 100, or 200 mg·liter<jats:sup>-1</jats:sup> from NH<jats:sub>4</jats:sub>NO<jats:sub>3</jats:sub> or 0, 3.13, 6.25, 12.5, 25, or 50 mg·liter<jats:sup>-1</jats:sup> from NH<jats:sub>4</jats:sub>NO<jats:sub>3</jats:sub> dissolved in a complete nutrient solution, respectively. Percentage of N in the mature plant tissues increased as N concentration in the medium solution increased. Shoot length and leaf area increased as N concentrations increased up to a critical concentration of 15 to 19 mg·liter<jats:sup>-1</jats:sup>. The critical N concentration for root, shoot, and total plant dry weight was ≈18 mg·liter<jats:sup>-1</jats:sup> for `Hamlin'-Cleopatra mandarin nursery plants and 15 mg·liter<jats:sup>-1</jats:sup> for `Hamlin'-Carrizo nursery plants. The critical N concentration for relative total plant dry weight accumulation (percentage) for the two experiments was 16.8 mg·liter<jats:sup>-1</jats:sup>. In a separate experiment, plants were given labeled fertilizer N (FN) (<jats:sup>15</jats:sup>NH<jats:sub>4</jats:sub><jats:sup>15</jats:sup>NO<jats:sub>3</jats:sub>) at one of five growth stages: A) in the middle of rapid shoot extension of the third flush, B) immediately following the cessation of the third flush shoot extension but during leaf expansion, C) immediately following leaf expansion, D) before the fourth flush, or E) in the middle of rapid shoot extension of the fourth flush. Labeled FN recovery increased during rapid shoot extension of the fourth scion flush compared to the other labeling periods. FN uptake per gram of total plant dry weight was greatest during rapid shoot extension (A and E) and lowest during the intermediate labeling periods (B-D). FN supplied 21% to 22% of the N required for new growth during rapid shoot extension.</jats:p>

Influence of nitrogen availability on shoot development in young peach trees [ Prunus persica (L.) Batsch]

“…Maust and Williamson (1994) discussed growth reduction of citrus trees raised in containers and provided weekly with 1.4 g N tree -1 , which is less than our N2 treatment (2.1 g N tree -1 ). However, Ro and Park (2000) pointed out that growth reduction in their study probably arose from toxic concentrations in the root vicinity that are common in pot experiments.…”

“…High N availability favours allocation to shoots, especially to leaves (Delap 1967;Taylor and May 1967;Lee and Titus 1992;Ro and Park 2000). It also increases the N content of all organs (Hill-Cottingham and Williams 1967;Maust and Williamson 1994) that can alter the quality of fruits such as apples (Klein et al 1989;Raese and Drake 1997). Furthermore, over fertilisation may cause groundwater pollution by nitrate leaching (Merwin et al 1996) and can decrease tree productivity due to excessive vegetative growth or increased tree sensitivity to pests (Weinbaum et al 1992;Daane et al 1995).…”

Influence of Soluble and Slow-Release Fertilizers on Vegetative Growth of Containerized Citrus Nursery Trees

“…Daily fertigation with NH 4 NO 3 in 'Hamlin' sweet orange (Citrus sinensis L. Osbeck) budded on 'Cleopatra' mandarin and 'Carrizo' citrange (Citrus sinensis × Poncirus trifoliata) presented greater nursery-tree growth when applied at 0.015 g L −1 (Maust and Williamson, 1999 An alternative fertilization technique in greenhouses involves the use of slow-release encapsulated fertilizers (Ballester-Olmos et al, 1992). This type of fertilizer eliminates the need for constant applications of nutrients due to total incorporation in the substrate before planting.…”

“…One possible explanation would be that lower concentrations of fertilizer would lead to lower E.C. or salinity rates, considering the same volume of substrate and available water in all treatments, and this in turnmight have led to better environmental conditions for the root-system development (Maust and Williamson, 1999).…”

Soil Temperature, Nitrogen Concentration, and Residence Time Affect Nitrogen Uptake Efficiency in Citrus

“…However, root adaptation may be too slow to make efficient use of greatly fluctuating N concentrations associated with high application rates of dry fertilizer. Seasonal variations in N uptake also occur, with uptake appearing to be highest during periods of active shoot growth (Maust and Williamson, 1994; Weinbaum et al, 1978). Roots in natural ecosystems are typically exposed to relatively low (<1 mg N L −1 ) N concentrations, and roots have been shown to be capable of depleting nutrients well below this level (Bloom, 1996; Cerezo et al, 1997).…”