Diagnostic leaf nutrient standards for low-chill peaches in subtropical Australia

A leaf nutrient survey was conducted of the low-chill peach cultivars, Flordaprince (October maturing) and Flordagold (mid November–early December maturing) at 3 commercial sites in both northern New South Wales and southern Queensland. Recently mature leaves from the middle third of a current season’s fruiting lateral (spring flush) were sampled at stone hardening and 2-weeks postharvest and of a non-fruiting lateral at maturity of the summer flush (after summer pruning) during the 1992–93 and 1993–94 seasons. At an additional site in New South Wales (Alstonville), leaf nutrient concentrations were also determined on cv. Flordagem (early November maturing) at 2-week intervals during both seasons. Soil (0–30 cm) chemical determinations were conducted at all sites at 2-weeks postharvest Seasonal trends in leaf nutrient composition were associated with a leaf age–maturity effect. As flush leaves matured during spring, and as mature leaves aged after hardening of the summer flush, nitrogen (N) concentration declined and calcium (Ca) concentration increased. Nitrogen and Ca concentrations increased when young leaves produced from the summer flush were sampled. Time of sampling produced the most consistently significant (P<0.05) main effects on leaf nutrient concentration. The 2-week postharvest period was selected as a convenient time to sample—when leaves were of a consistent age and maturity, and the effect of crop load on tree nutrient reserves was still present. Paclobutrazol, which reduces vegetative growth in stonefruit, was applied to all Queensland sites and, as a consequence, mid lateral leaves contained higher (P<0.05) Ca, magnesium (Mg) and chloride (Cl) and lower (P<0.05) N and phosphorus (P) concentrations than leaves from New South Wales sites. State effects can therefore be interpreted as paclobutrazol effects. Cultivar effects (P<0.05) occurred for many leaf nutrients, however, at the 2-week postharvest sampling, concentrations were sufficiently similar to combine as a narrow adequate concentration range for both cultivars. The diagnostic adequate leaf nutrient concentrations were within the range developed for high-chill peaches (Leece et al. 1971) with the exception of lower Ca, lower Mg for New South Wales (both cultivars), lower iron for Flordaprince (both states), higher P for Flordaprince in New South Wales and higher manganese values for Queensland (both cultivars). Regression analyses were conducted between leaf and fruit nutrient concentrations and soil chemical properties. The only consistent result demonstrated that as the soil Ca : Mg ratio increased, leaf Mg concentration decreased exponentially (P<0.001), indicating that the practice of heavy annual agricultural limestone or gypsum applications in the absence of Mg fertiliser, which had been adopted by several growers in the survey, is associated with lower leaf Mg concentrations

Absorção de nutrientes pelo tomateiro cultivado sob condições de campo e de ambiente protegido Nutrient absorption by tomato plants grown under field and protected conditions

Foram realizados dois experimentos, na Universidade Federal de Viçosa, objetivando caracterizar a absorção de nutrientes pelo tomateiro cultivado sob condições de campo e de ambiente protegido. O primeiro, com a cultivar Santa Clara, cultivada a campo, no sistema de cerca cruzada e sete cachos. O segundo, em estufa plástica, com o híbrido EF-50, conduzidas verticalmente, mantendo-se oito cachos em cada uma. Ambos experimentos foram delineados em blocos ao acaso, com quatro repetições. O primeiro constituído por oito e o segundo por nove tratamentos. Em ambos experimentos, o padrão de absorção de nutrientes seguiu o acúmulo de matéria seca pelas plantas. No experimento de campo, a ordem decrescente de acúmulo de nutrientes na parte aérea foi: K, N, Ca, S, P, Mg, Cu, Mn, Fe e Zn, alcançando os valores máximos de 360; 206; 202; 49; 32; 29 kg.ha-1; 3.415; 2.173; 1.967 e 500 g.ha-1, respectivamente. Em ambiente protegido, o acúmulo de nutrientes na parte aérea do tomateiro decresceu na seguinte ordem: K, N, Ca, S, Mg, P, Mn, Fe; Cu e Zn, alcançando os valores de 264; 211; 195; 49; 40; 30 kg.ha-1; 3.200; 2.100; 1.600 e 700 g.ha-1, respectivamente. As taxas de absorção diária dos nutrientes são apresentadas bem como as porcentagens de absorção do N e de K em determinados períodos do crescimento do tomateiro, visando auxiliar na programação das épocas de aplicação destes nutrientes em cobertura.<br>Two experiments were conducted at Universidade Federal de Viçosa to evaluate nutrient absortion by tomato plants grown under field and protected conditions. In the first experiment, tomato cv. Santa Clara was grown in the field with seven clusters/plant. In the second one tomato hybrid EF-50 was grown in plastic greenhouse and pruned to eight clusters. Both experiments were designed as randomized blocks, with four replicates. The first and second experiments were performed with eight and nine treatments, respectively. In both experiments, the nutrient absorption patterns followed the plant dry matter accumulation. In the field experiment, the amounts of nutrient uptaken by the plants decreased following the order K, N, Ca, S, P, Mg, Cu, Mn, Fe and Zn reaching their maximal values of 360; 206; 202; 49; 32; 29 kg ha-1; and 3415; 2173; 1967 and 500 g ha-1, respectively. In the greenhouse experiment, the order was K, N, Ca, S, Mg, P, Mn, Fe, Cu, and Zn reaching their maximal values of 264; 211; 195; 49; 40; 30 kg ha-1; and 3227; 2121; 1639 and 651 g ha-1, respectively. Nutrient daily absorption rates are presented as well as the percentages of N and K uptaken at determined tomato plant growth period, which can be helpful to program the time of sidedressing of those nutrients

The effects of spatial pattern of nutrient supply on yield, structure and mortality in plant populations

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