Estresse hídrico em mudas de Astronium graveolens jacq.
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Data
2018-01-19
Autores
Sifuentes, Maria Vitória Barros [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As práticas silviculturais de manejo em viveiros florestais têm grande influência na qualidade e sobrevivência das mudas depois de plantadas em campo e estão também diretamente relacionadas com atributos de crescimento e fisiológicos das plantas jovens. A etapa de produção que tem por objetivo aclimatar as mudas e torná-las aptas ao plantio e mais resistentes às adversidades ambientais é denominada rustificação, sendo aplicada na última fase de produção de mudas. Nesse sentido os objetivos deste trabalho foram: verificar de que forma o manejo hídrico aplicado à muda na fase de rustificação afeta as variáveis de crescimento e fisiológicas das mudas de Astronium graveolens Jacq. e, como este manejo afeta a sobrevivência e desenvolvimento inicial das mudas em condições de vaso (simulação de condições de campo). O delineamento experimental adotado foi inteiramente ao acaso com 4 tratamentos aplicados durante 50 dias: T1, T2 e T3 - mudas irrigadas quando o substrato atingia uma tensão de retenção de água de -10 KPa, -100 KPa e -1500 KPa, respectivamente; T4- mudas permanentemente na irrigação. Cada tratamento foi composto por 5 repetições (5 bandejas com 25 plantas). Foram avaliados: atributos morfológicos (altura, diâmetro do colo, massas secas de raiz, caule e folha e área foliar; fisiológicos (trocas gasosas, potencial hídrico foliar e conteúdo relativo de água). Depois as mudas foram mantidas em vaso por 130 dias. Os dados foram submetidos a ANOVA simples e de dois fatores. As massas secas de raiz e total diminuíram com o aumento do nível de estresse. As análises de trocas gasosas e de potencial hídrico mostraram a formação de dois grupos ecofisiológicos após a aplicação da rustificação: T1- plantas não estressadas e T2, T3 e T4- plantas estressadas. As mudas alteraram seu padrão fisiológico apontando uma adaptação (aclimatação) às condições ambientais a que foram submetidas. Ao final dos quatro meses de plantio em vaso T3 apresentou o melhor desempenho com maior biomassa e trocas gasosas mais eficientes
The silvicultural management applied in nurseries influences seedling quality and survival after field planted and are also related to morphological and physiological traits. The last stage of seedling production in nurseries is called hardening and its objective it is to acclimate the plants making them able to cope with field planting. The hardening phase comprises in a management with no fertilizing and low levels of water to the plant inducing drought acclimation. The aim of this study was verifying the relationship between hardening irrigation in the production of Astronium graveolens seedlings with its morphological and physiological traits and also if the hardening treatments influence their field performance after outplanting. Plants were submitted to four different treatments during 50 days: T1, T2 e T3- seedlings were irrigated when substrate water tension reached -10 KPa, -100 KPa and -1500 KPa, respectively; T4- seedlings were permanently capillarity irrigated. Each treatment was compound with five repetitions (five trays with 25 plants each). We assessed morphological traits as stem height, stem diameter, root dry mass, stem and leaves dry mass and leaf area; assessing physiological traits as gas exchange and leaf water potential. The experimental design was completely randomised, a one-way and two-way ANOVA were performed. Root, stem and leaf dry mass decreased with increasing drought stress, and also to flood stress. Gas exchange and leaf water potential assessment suggest the formation of two ecophysiological groups after hardening treatment: T1- non-stressed plants and; T2, T3 and T4 stressed plants. Seedlings changed their physiological behavior pattern resulting in an acclimation to the environmental conditions they were submitted. After four months planted in vases, T3 seedlings showed the highest biomass and a more effective gas exchange
The silvicultural management applied in nurseries influences seedling quality and survival after field planted and are also related to morphological and physiological traits. The last stage of seedling production in nurseries is called hardening and its objective it is to acclimate the plants making them able to cope with field planting. The hardening phase comprises in a management with no fertilizing and low levels of water to the plant inducing drought acclimation. The aim of this study was verifying the relationship between hardening irrigation in the production of Astronium graveolens seedlings with its morphological and physiological traits and also if the hardening treatments influence their field performance after outplanting. Plants were submitted to four different treatments during 50 days: T1, T2 e T3- seedlings were irrigated when substrate water tension reached -10 KPa, -100 KPa and -1500 KPa, respectively; T4- seedlings were permanently capillarity irrigated. Each treatment was compound with five repetitions (five trays with 25 plants each). We assessed morphological traits as stem height, stem diameter, root dry mass, stem and leaves dry mass and leaf area; assessing physiological traits as gas exchange and leaf water potential. The experimental design was completely randomised, a one-way and two-way ANOVA were performed. Root, stem and leaf dry mass decreased with increasing drought stress, and also to flood stress. Gas exchange and leaf water potential assessment suggest the formation of two ecophysiological groups after hardening treatment: T1- non-stressed plants and; T2, T3 and T4 stressed plants. Seedlings changed their physiological behavior pattern resulting in an acclimation to the environmental conditions they were submitted. After four months planted in vases, T3 seedlings showed the highest biomass and a more effective gas exchange
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Palavras-chave
Viveiros florestais, Manejo hídrico, Aclimatação vegetal, Forestry nurseries, Irrigation management, Plant acclimation