Changes in drought tolerance of Pinus radiata in Chile associated with provenance and breeding generation

International audienceAbstractKey messageIn Chile, breeding radiata pine for growth has led to drifts in the degree of drought tolerance of the seedlings. Interior provenances gained a larger tolerance to drought after three breeding generations as shown by larger survival and root/shoot ratio under water shortage, while coastal provenance displayed an opposite trend.•Context Given that rainfall is predicted to decrease and to affect establishment and early survival of radiata pine (Pinus radiata D. Don) in Chile, there is a need to identify more drought tolerant genotypes at seedling stage.•Aims The aim of this study was to test whether provenances of P. radiata originating from interior or from coastal provenances, displayed different responses to short-term water shortage, and whether these responses differed from the first to the third breeding generation.•Methods Three generations of breeding families from two sites in Central Chile were compared. The seedlings were grown during 100 days and subjected to two watering regimes for 45 days. Survival, growth, and biomass allocation to roots and shoots were recorded.•Results The two provenances displayed different responses to drought. Biomass allocation to shoots and survival were significantly reduced by water shortage. The first generation seedlings from the coastal provenance displayed a larger survival rate when exposed to water shortage (i.e., 60 %); this rate decreased in the following breeding generations. On the contrary, the survival rate increased from the first to the third generation in the interior provenance.•Conclusions We observed an important local adaptation to water shortage in the interior provenance. This response may be due to the fact that parent tree populations of the interior provenance have successfully adapted to sites with periodic drought

Efectos combinados de la restricción hídrica, el tamaño de contenedor y la dosis de fertilizante en la supervivencia, intercambio gaseoso y atributos morfológicos en plantas de Quillaja saponaria

Quillaja saponaria is a valuable commercial and ecological Chilean native species that has suffered considerably degradation countrywide; however, the determination of the optimum characteristics of the planting stock, an important aspect in restoration projects, has receive little attention. The aim of this study was to evaluate the effect of container size and dose of fertilizer on morphological and physiological responses of Q. saponaria seedlings cultivated in a nursery under well-watered and water restricted conditions. After 27 days growing under contrasting watering regimes, growth, biomass allocation, and gas exchange were measured in 6-month-old seedlings. We found that survival, height and diameter increment, and root dry weight were higher in the water stressed seedlings cultivated in large containers. The water stressed seedlings cultivated in large containers also had superior stomatal conductance, however when the fertilizer dose was decreased, this trait decreased considerably. Thus, a superior performance in a water-restricted environment could be expected in those seedlings cultivated in larger containers with low fertilizer.Quillaja saponaria es una especie nativa del bosque nativo chileno valiosa por sus cualidades económicas y ecológicas y que ha sufrido una importante degradación a lo largo del país; sin embargo, la determinación de las características óptimas del material de plantación, un aspecto importante en proyectos de restauración, ha recibido poca atención. El objetivo de este estudio fue evaluar el efecto del tamaño de contenedor y la dosis de fertilizante en la respuesta morfológica y fisiológica de plantas de Q. saponaria cultivadas bajo dos regímenes de riego en vivero (riego normal vs. restricción hídrica). Después de 27 días de crecimiento bajo condiciones de riego contrastantes, se evaluó el crecimiento, la asignación de biomasa y variables de intercambio gaseoso en plantas de seis meses de edad. Los resultados indican que en el tratamiento de restricción hídrica las plantas cultivadas en contenedores grandes mostraron la mayor supervivencia, incremento en diámetro y altura y biomasa radical. Las plantas del tratamiento de restricción hídrica cultivadas en contenedores grandes también mostraron tasas superiores de conductancia estomática, sin embargo, cuando se disminuyó la dosis de fertilizante, esta variable disminuyó considerablemente. Se podría esperar que, aquellas plantas cultivadas en contenedores de mayor volumen y con dosis baja de fertilizante, tuvieran un mejor desempeño en ambientes con restricción hídrica.CONICYT 79150013 CONAF 067-201

Differential adaptations in nursery seedlings from diverse Chilean provenances of Peumus boldus Mol.

Seed germination, seedling growth and biomass allocation of the endemic species Peumus boldus Mol. (Boldo) were studied in four provenances (two northern and two southern provenances) from central Chile. Seeds collected from five different mother plants for each provenance were sowed in plastic pots and placed in an ambient nursery. Germinated seeds were transplanted to 130-mL containers and cultivated under nursery conditions during one growing season. Germination capacity, seed weight, morphological traits of seedlings (root collar diameter, height, number of leaves, foliar area, root length), their biomass allocation pattern (dry mass of leaves, shoots and roots) and survival were analyzed. Results showed significant differences among provenances and mother plants for most traits. Northern provenances showed slower germination, smaller size, higher root biomass, lesser leaf area, and higher survival, while seedlings from southern provenances were taller, with more body mass, larger leaf area and lower root biomass. We concluded that northern provenances of Peamus boldus are more tolerant to drought and therefore are suitable for ecological restoration of drought-prone Mediterranean sites, while the use of southern provenances must be restricted to restoration of more humid environments

Effect of Temperature on the Germination of Five Coastal Provenances of Nothofagus glauca (Phil.) Krasser, the Most Representative Species of the Mediterranean Forests of South America

Temperature is one of the most important abiotic factors affecting seed germination, and it is strongly influenced by local site conditions. Seeds of Nothofagus glauca, an endemic and vulnerable species of the Mediterranean region of Chile and the most representative of the Mediterranean forests of South America, were collected. In this study, we evaluated the effect of temperature on different germinative attributes of five N. glauca provenances representative of their natural distribution. The seeds were treated at a constant temperature (i.e., 18 °C, 22 °C, 26 °C, or 30 °C) in the absence of light for 40 days. The results show that in all the provenances, the germination ratio and energy increase linearly with temperature until reaching an optimum temperature (i.e., 22 °C), above which they decrease severely. At 22 °C, the response of average germination speed and germination vigor was significantly higher than with the other temperatures (performance of germination start day was not clear). The base temperature was around 18 °C and the maximum, above 30 °C, which may be close to thermo-inhibition. Given the threat of climate change, it is necessary to increase research in terms of the possible adaptation of this species to increased temperatures and prolonged periods of drough

Field performance of various Pinus radiata breeding families established on a drought-prone site in central Chile

Background: Pinus radiata D. Don is in its third generation of selective breeding on contrasting site types in central Chile, creating interest in its responses to selection and any differential adaptation to site types. We studied the phenotypic variability of growth traits, survival and six ecophysiological traits in 30 open- and control-pollinated families, representing two breeding regions and three breeding generations, in a 2-year-old P. radiata field trial on a sandy soil in the Mediterranean drylands of Central Chile. Findings: Growth, survival and the ecophysiological traits did not differ between the regional origin of the breeding populations. However, breeding-generation effects were significant for height and diameter. As expected, growth traits showed progressive improvement with successive generations. Individual-family effects were evident for all traits except one ecophysiological trait. Conclusions: Breeding has evidently improved early growth performance in the field, despite no clear effect of regional breeding population, but no such effects were observed for the ecophysiological traits. Despite the current study demonstrating considerable family variation at age 2 years, it is unclear how these results relate to performance of mature trees in the field.CONICYT, 11121484, 7915001

Effect of crop management intensity on energy and carbon dioxide balance of two bioenergy Sorghum bicolor hybrids

Although bioenergy sorghum has many traits that make it ideal for biofuel production, management conditions that can affect the productivity and sustainability of these systems are still poorly understood. This paper estimated the energy and CO2 balance of two bioenergy sorghum (Sorghum bicolor L. Moench.) hybrids (H128 and H133) cultivated during two growing seasons and under two different levels of crop management, high and low input. At the end of both growing season, sorghum was harvested for biomass yield determination. Calorific value and net energy production were also estimated. Crop management had important effects on sorghum CO2 and energy balance. The energy produced varied between 126 and 365 GJ ha–1 depending on crop management, hybrid and growing season. Regarding of the CO2 balance, the high level of crop management had a superior CO2 emission. However, the energy produced per kg of CO2 emitted was higher (>300%) than the energy produced with the use of fossil fuels. The use of bioenergy sorghum can contribute to better energy sustainability and reduced CO2 emission in Mediterranean ecosystems

Early Effects of Mycorrhizal Fungal Inoculum and Fertilizer on Morphological and Physiological Variables of Nursery-Grown <i>Nothofagus alessandrii</i> Plants

Nothofagus alessandrii (ruil) is an endangered relict species, endemic to the Mediterranean area of Chile, and one of the most threatened trees in the country. Its natural distribution area has been greatly reduced by the effect of human activities; the remaining fragments are mostly intervened and highly deteriorated as a habitat and refuge for the associated biodiversity. In order to produce healthy and resistant nursery plants for recovery and restoration of N. alessandrii forests, this study evaluates the early effects of mycorrhizal fungal inoculum (MFI) combined with fertilization on the cultivation of seedlings. The experiment was established under a completely randomized design with a factorial arrangement of the mycorrhizal factors (M0 = without mycorrhizal, M1 = Thelephora sp. and M2 = Hebeloma sp.) and fertilization (F1 = standard fertilization and F2 = intensive fertilization), with three replicates of each combination, for each type of plant (P1 = plants from one season and P2 = plants from two seasons). Each experimental unit corresponded to a group of 20 plants, with 720 plants in the test. The results indicate that application of fertilizer and MFI significantly affects some growth and photosynthesis parameters of ruil plants in one and two seasons. The morphological parameters obtained in the study show shoot height values ranging between 67 and 91 cm for P1 and between 96 and 111 cm for P2; while, for shoot diameter, values ranged between 7.91 and 8.24 mm for P1 and between 10.91 and 11.49 mm for P2. Although formation of fully developed mycorrhizal roots was not observed during the assay period, we conclude that inoculation of mycorrhizal fungi combined with fertilization could be an efficient strategy to produce a quality plant, in addition to maintaining a high photosynthetic capacity and, therefore, a higher percentage of survival in the field