Alfalfa (Medicago sativa L. subsp. sativa) has emerged as an alternative crop for Mediterranean dryland areas in Chile. These soils show deficient nutritional levels affecting legume nodulation and N fixation through symbiosis with Ensifer meliloti. The objective of this work was to select plant growth promoting rhizobacteria (PGPR) associated with alfalfa and to evaluate their effects in plant growth and nodulation. Bacterial strains were isolated from the rhizosphere of alfalfa cultivated in dryland soil in Mediterranean areas of Chile. The 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, production of indole acetic acid (IAA), phosphate solubilization and the compatibility with E. meliloti was assessed for each strain. The selected bacterial strains were identified by the amplification of the 16S rRNA gene. Twelve of the 32 isolated strains were compatible with E. meliloti as they did not show signs of antagonism. Eight strains solubilized phosphate, 12 produced IAA ranging from 13.71 to 26.22 mg L^-1 and only the GN-8 isolate reported ACC deaminase activity. In the plants, the nodulation was greater when the strain with ACC deaminase and E. meliloti were co-inoculated both in laboratory and greenhouse conditions (P < 0.05). The selected bacteria GN-2 and GN-8 belonged to the genus Bacillus, while GN-4 to Pseudomonas. In conclusion, PGPR collected in marginal soils of Mediterranean areas of Chile showed ACC deaminase activity, IAA production and phosphate solubilization. The co-inoculation with E. meliloti and Bacillus sp. GN-8 allowed earlier nodulation in alfalfa.

Blueberry exports that imply transport times of more than 25 d deteriorate their quality. The use of elicitors in preharvest has shown positive effects on the quality of berries such as grapes. The objective of this study was to evaluate preharvest applications (21, 14, and 7 d before harvest) of oxalic acid (OA) and salicylic acid (SA) on fruit firmness and phenolic compounds in blueberry. The treatments of 0, 2, and 4 mM OA in ‘Kirra’ and 0, 2, and 4 mM SA are in ‘Stella blue’. With the earlier preharvest application, ‘Kirra’ presented better firmness than ‘Stella blue’; however, 2 mM OA and SA in both cultivars increased fruit firmness, maintaining its weight and diameter with respect to the control. It should be noted that the treatment with 2 mM SA generated a 100% increase in polyphenolic content and antioxidant capacity (p < 0.05) in ‘Stella Blue’, with values close to 140 mg gallic acid 100 g⁻¹ and 80 mg 100 g⁻¹ fresh weight (FW), respectively. In Kirra, OA treatments did not have a significant impact on the polyphenol content, but 4 mM OA increased by 100% and 20%, total anthocyanin and antioxidant capacity of blueberry fruit, respectively. Based on our results, three pre-harvest applications of OA and SA during the fruit development until the beginning of ripening improve fruit firmness by up to 20% at different times of harvest.

Seed viability of domesticated and cultivated Capsicum species: Capsicum annuum L., Capsicum baccatum L., Capsicum chinense Jacq., Capsicum frutescens L., and Capsicum pubescens Ruiz and Pav. was tested by the tetrazolium method. The seeds were soaked in three tetrazolium salt solutions of 1, 0.5 and 0.2%, and temperature conditions of 30 - 35 C for 3 h. The percentage of seeds stained in relation to the total number of seeds was evaluated. To estimate germination, the seeds were subjected to chemical treatments with gibberellic acid (GA3) at doses of 0, 100, 200, 300, and 400 mg L-1 at room temperature for 24 h. The germination rate was estimated, while plant height was evaluated at 10, 20 and, 30 days after sowing (DAS). Capsicum seed viability fluctuated between 52.44% and 97.11%. The highest percentage of viability was obtained with the 1% dose of tetrazolium (81.63%), while the 0.2% dose resulted in the lowest average value (63.7%). In addition, C. annuum, C. baccatum and C. chinense showed high staining patterns, while most of the observed patterns in C. frutescens corresponded to non-viable seeds. After GA3 application, average seed germination was 100% in C. chinense; 75.6% in C. baccatum; 73.32% in C. annuum; and 61.5% in C. frutescens. However, the application of GA3 did not cause an additional effect on the germination of Capsicum seeds. The highest plant height at 30 DAS was observed in accessions of C. annuum (9.08 cm), while C. chinense presented the lowest value (4.49 cm).

La producción de plántulas de plátano de calidad vía macropropagación en cámara térmica es una metodología económica y eficiente para pequeños productores. El objetivo de la investigación fue evaluar el efecto de bencilaminopurina y tipo de brotes sobre la tasa de multiplicación de cormos y la calidad de plántulas de plátano propagadas en cámara térmica. Se desarrollaron dos experimentos separados. En el primero se probó el efecto de bencilaminopurina (BAP) sobre la tasa de multiplicación de cormos de plátano en cámara térmica, donde se establecieron dos tratamientos que fueron: Con BAP (40 mg L-1) y sin BAP. En el segundo se evaluó el potencial de enraizamiento, crecimiento y calidad de plántulas de plátano en vivero, generadas a partir de dos tipos de brotes en cámara térmica, que fueron: Brotes adventicios de segunda generación (BAR2) y brotes procedentes de tejido calloso (BCR2). En ambos experimentos los datos fueron analizados con prueba estadística de t de Student para observaciones pareadas. Se registró la tasa de multiplicación, variables de crecimiento y calidad de plántulas en vivero. La mayor tasa de multiplicación de brotes en cámara térmica se produjo con BAP, que supero en 44 % al tratamiento sin BAP. El mayor crecimiento e índice de calidad de Dickson en plántulas durante la aclimatación fue logrado con brotes adventicios (BAR2). La calidad se correlacionó positivamente con variables morfométricas de las plántulas. El uso de BAP y brotes adventicios (BAR2) es efectivo para incrementar tasa de multiplicación y calidad de plántulas de plátano macropropagadas.

The macro-propagation of plantain in a thermal chamber is an economical and efficient alternative method for quality seedling production. The aim of the research was to evaluate the effect of various substrate types and different sprout sizes on the production and quality of plantain seedlings propagated in a thermal chamber. Two separate experiments were performed. 1) To test the effect of four substrates on the plantain sprout production in a thermal camera, using cattle manure composted (CC), cattle manure composted + peanut husk (CC + PH), cattle manure composted + rice husk (CC + RH), and cattle manure composted + white sawdust (CC + WS). The sprout multiplication rate was recorded. 2) To test the effect of three sprout sizes on the growth and seedling quality in the nursery phase, using type A (6-10 cm), type B (11-15 cm), and type C (16-20 cm) sprouts. Variable growth and seedling quality were measured. A completely randomized design was used in both experiments. Analyses of variance and comparison of means (Tukey, p ≤ 0,05) were performed. The highest sprout multiplication rate was obtained with the CC + RH substrate. The highest growth and Dickson quality index on seedlings in the acclimatization phase were obtained with type C sprouts. The type of substrate and the size of the sprouts were decisive in the production and quality of macro-propagated plantain seedlings. La macropropagación de plátano en cámara térmica es un método alternativo, económico y eficiente en la producción de plántulas de calidad. El objetivo de la investigación fue evaluar el efecto de varios tipos de sustratos y diferentes tamaños de brotes en la producción y calidad de plántulas de plátano propagadas en cámara térmica. Se desarrollaron dos experimentos separados. En el primero, se probó el efecto de cuatro sustratos sobre la producción de yemas de plátano en cámara térmica, usando bovinaza compostada (BC), bovinaza compostada + cascarilla de maní (BC + CM), bovinaza compostada + cascarilla de arroz (BC + CA) y bovinaza compostada + aserrín blanco (BC + AB), y se registró la tasa de multiplicación. En el segundo, se evaluó el efecto de tres tamaños de brotes sobre el crecimiento y calidad de plántulas en fase de vivero, usando brotes tipo A (entre 6-10 cm), tipo B (entre 11-15 cm) y tipo C (entre 16-20 cm), y se midieron variables de crecimiento y calidad de plántulas. En ambos experimentos, se utilizó un diseño completamente aleatorizado. Se realizó análisis de varianza y comparación de medias (Tukey, p ≤ 0,05). La mayor tasa de multiplicación de plántulas se produjo con el sustrato BC + CA. El mayor crecimiento e índice de calidad de Dickson en plántulas durante la aclimatación se produjo en brotes tipo C. El tipo de sustrato y tamaño de brote fueron determinantes en la producción y calidad de plántulas de plátano macropropagadas.