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C. Larrigaudiere, E. Pinto, and M. Vendrell

The differential effects of two color improving products, ethephon an ethylene-releasing compound, and seniphos, a nonethylene-releasing product, were studied on `Starking Delicious' apples (Malus domestica Borkh L.). Ethephon and seniphos were applied 2 or 3 weeks before commercial harvest. Ethephon- and seniphos-treated fruit showed a significant improvement of peel color associated with a sharp increase in anthocyanin content and chromaticity values. Color improvement in ethephon-treated apples occurred during the preharvest period and cold storage. The seniphos-treated fruit stopped color development in cold conditions. In comparison to the ethephon-treated fruit, the seniphos-treated apples showed lower internal ethylene concentrations and a ripening delay. Both treatments sharply increased the activity of phenylalanine-ammonia-lyase enzyme, which seemed to be the determining factor of color enhancement. The seniphos-treated apples compared to ethephon had higher fruit firmness and lower soluble solids concentrations. Anthocyanin biosynthesis may be enhanced by seniphos treatment without inducing ethylene production or other ripening associated changes. As a consequence, fruit treated with seniphos can be held longer in storage.

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José E.B.P. Pinto, Clovis M. Souza, and W.R. Maluf

Hybrid cabbage cultivars can be produced via seed-propagated self-incompatible (SI) inbred lines, or, alternatively, via vegetative propagation of SI clones. Cabbage clones differ in their ability to undergo vegetative propagation, a fact that appears to be related to the degree of differentiation of the axillary buds inside the head. A procedure for in vivo and in vitro propagation is described for cabbage clones known for difficulty in undergoing vegetative propagation. Cuttings from clonal families 800 (easy-to-propagate) and 007 (difficult to propagate) were immersed in indolebutyric acid (IBA—0, 5, 25, and 125 mg·L–1) + boric acid (100 mg·L–1) + sucrose (20 g·L–1) for 15 hours and maintained in glasshouses. Induction of roots was more effective with 125 mg·L–1 IBA supplemented with boric acid and sucrose. This treatment showed the highest frequency of rooting and the largest number of roots per cutting. The in vitro system of propagation was performed on the basal medium of Murashige and Skoog (MS), to which triadizuron (TDZ), benzyladeninepurine (BAP), and kinetin (Kin) were added in different combinations. TDZ was more effective than BAP or Kin in the promotion of shoot regeneration.

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L.F. Rosal, J.E.B.P. Pinto, S.K.V. Bertolucci, L.C.B. Costa, and R.M. Corrêa

The aim of the present work was to establish appropriate conditions for the in vitro micropropagation of Eremanthus erythropappus (DC.) MacLeish through shoot multiplication on apical and nodal bud explants. Explants were excised from in vitro-grown seedlings and incubated on Murashige and Skoog medium containing different combinations of 6-benzylaminopurine (BAP) and 1-naphthalene acetic acid (NAA) (for apical buds) and gibberellic acid and NAA (for nodal segments). Proliferation of apical shoots was successfully achieved in the presence of BAP and NAA, each at 1.0 mg L−1, while the elongation of apical shoots could only be attained on medium containing NAA at 1.0 mg L−1. Elongation of nodal shoots was induced in the presence of NAA at 2.0 mg L−1. The most suitable medium for inducing root proliferation on explants of E. erythropappus was NAA at 1.0 mg L−1.

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Ana V. de Souza, José E.B.P. Pinto, Suzan K.V. Bertolucci, Ricardo M. Corrêa, Larissa C. do B. Costa, and William E. Dyer

Lychnophora pinaster, known as arnica, is a medicinal plant of the Cerrado ecosystem in Brazil. It is widely used in the form of alcoholic extract for its anti-inflammatory and anesthetic and healing effects on sprains, bruises, and inflammation. Owing to the great difficulty of propagation, it is listed by the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis in the category of plants vulnerable to extinction. Micropropagation offers a solution to this problem by allowing the preservation and expansion of germplasm. The objective of this research was to establish a protocol for in vitro propagation of arnica. The best medium for germination of arnica embryos and plantlet growth was a quarter strength semisolid Murashige and Skoog medium (MS/4) containing 0.75% (w/v) sucrose. For shoot induction, the best results were obtained on MS/4 with 2.76 μm of benzylaminopurine. Maximum shoot elongation before rooting occurred in the presence of 8.67 μm of gibberellic acid for 19 d. Microshoots were successfully rooted in the presence of 10.7 μm of naphthalene acetic acid for 15 d. After rooted plantlets were acclimatized in a greenhouse for 20 d, the survival rate was 100% when planted in a soil from the area of occurrence of the species, whereas 0% survived when planted in Plantmax.

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Salvatore Campisi-Pinto, Yusheng Zheng, Philippe E. Rolshausen, David E. Crowley, Ben Faber, Gary Bender, Mary Bianchi, Toan Khuong, and Carol J. Lovatt

Optimizing ‘Hass’ avocado (Persea americana Mill.) tree nutrient status is essential for maximizing productivity. Leaf nutrient analysis is used to guide avocado fertilization to maintain tree nutrition. The goal of this research was to identify a ‘Hass’ avocado tissue with nutrient concentrations predictive of yields greater than 40 kg of fruit per tree. This threshold was specified to assist the California avocado industry to increase yields to ≈11,200 kg·ha−1. Nutrient concentrations of cauliflower stage inflorescences (CSI) collected in March proved better predictors of yield than inflorescences collected at full bloom (FBI) in April, fruit pedicels (FP) collected at five different stages of avocado tree phenology from the end of fruit set in June through April the following spring when mature fruit enter a second period of exponential growth, or 6-month-old spring flush leaves (LF) from nonbearing vegetative shoots collected in September (California avocado industry standard). For CSI tissue, concentrations of seven nutrients, nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), sulfur (S), zinc (Zn), and copper (Cu) were predictive of trees producing greater than 40 kg of fruit annually. Conditional quantile sampling and frequency analysis were used to identify optimum nutrient concentration ranges (ONCR) for each nutrient. Optimum ratios between nutrient concentrations and yields greater than 40 kg per tree were also derived. The high nutrient concentrations characterizing CSI tissue suggest current fertilization practices (timing or amounts) might be causing nutrient imbalances at this stage of avocado tree phenology that are limiting productivity, a possibility that warrants further investigation. Because CSI samples can be collected 4–6 weeks before full bloom, nutritional problems can be addressed before they affect flower retention and fruit set to increase current crop yield, fruit size, and quality. Thus, CSI nutrient analysis warrants further research as a potential supplemental or alternative tool for diagnosing ‘Hass’ avocado tree nutrient status and increasing yield.