Low temperature is one of the main environmental constraints for rice (Oryza sativa L.) grain production yield. It is known that multi-environment studies play a critical role in the sustainability of rice production across diverse environments. However, there are few studies based on multi-environment studies of rice in temperate climates. The aim was to study the performance of rice plants in cold environments. Four experimental lines and six cultivars were evaluated at three locations during three seasons. The grain yield data were analyzed with ANOVA, mixed models based on the best linear unbiased predictors (BLUPs), and genotype plus Genotype × Environment interaction (GGE) biplot. High genotype contribution (> 25%) was observed in grain yield and the interaction between genotype and locations was not very important. Results also showed that 'Quila 241319' was the best experimental line with the highest grain yield (11.3 t ha -1 ) and grain yield stability across the environments; commercial cultivars were classified as medium grain yield genotypes.

Embothrium coccineum J.R. Forst. & G. Forst. (Proteaceae) is a tree that grows successfully in nutrient poor soils of southern Chile at full sunlight. Under these conditions it develops cluster roots (CR). However, the induction of CR on this species has not been studied completely. The aim of this work was to study the effect of seasonality, soil and weeds in the development of CR in E. coccineum. The present study was performed in Los Lagos Region (41º72' S lat), Chile. Plants of E. coccineum were grown in sandy soils in presence or absence of weeds, using two concentrations of organic matter. The number of CR per plant, CR mass and P concentration in leaves was measured during the four seasons in E. coccineum plants. The CR development in the soil with high organic matter concentration and without weeds was observed in autumn, spring and summer, and in the soil with low organic matter concentration was observed in autumn, winter and spring. Not found related of this result with the foliar P concentration in E. coccineum. The results suggest a strong seasonal and weeds effect on CR development in E. coccineum under field conditions.

Auxins play an important role in cluster root (CR) development in some species under low P conditions. However, the mechanism for CR induction in Embothrium coccineum J.R. Forst. & G. Forst remains unknown. Therefore, the aim of this work was to determine the effect of auxin on CR induction in E. coccineum, under low P conditions. For this, plants of E. coccineum were grown under P sufficiency and deficiency, and were treated with exogenous auxin and an auxin transport inhibitor. Phosphorous concentration in leaves, proportion of the total root allocated to CR mass (CRA), CR number (CRN), CR mass (CRm), and individual CR mass (ICRm), were measured. The number of CR showed a negative correlation with P concentrations in leaves. Furthermore, application of auxin in plants grown under P deficiency increased the CRA in a 50% and CRN in a 60%. The values of all parameters measured in plants grown under P deficiency conditions were reduced to less than half that observed in control plants, after foliar application of auxin transport inhibitor. However, no difference was observed when auxin was applied in plants grown with P supply. These results suggest that P and auxin are important factors for CR induction in E. coccineum.