Gas exchange and chlorophyll fluorescence responses of Pinus radiata D. Don seedlings during and after several storage regimes and their effects on post-planting survival

Abstract

Post-storage gas exchange parameters like CO 2 assimilation, stomatal conductance, transpiration, water use efficiency and intercellular CO 2 concentrations, together with several chlorophyll a fluorescence parameterswere examined in radiata pine (Pinus radiata D. Don) seedlings that were stored for 1, 8 or 15 days at 4°or 10°C with or without soil around the roots. Results were analysed in relation to post-storage water potential and electrolyte leakage in order to forecast their vitality (root growth potential) following cold storage, and post-planting survival potential under optimal conditions. During storage at 4°and 10°C, photosynthesis was reduced, being more pronounced in bare-root seedlings than in seedlings with soil around the roots. The depletion of CO 2 assimilation seemed not to be solely a stomatal effect as effects on chloroplasts contributed to this photosynthetic inhibition. Thus, the fall in the ratios F v /F m , F v /F o and F m /F o indicated photochemical apparatus damage during storage. Photosynthetic rate was positively correlated with the root growth index and new root length showing that new root growth is dependent primarily on current photosynthesis. Pre-planting exposure of bare-root radiata pine seedlings to temperatures of 10°C for more than 24 h during transportation or storage is not recommended.

Stomatal Development and Associated Photosynthetic Characteristics of Watermelon (Citrullus lanatus) Plug Seedlings during Light Storage

“…Carbon assimilation and dry mass accumulation. One important reason for better quality of seedlings stored in light mainly the result of the preservation of the photosynthetic ability (Kubota and Kozai, 1994;Mena-Petite et al, 2003), which would ensure the transplant quality of post-storage seedlings effectively (Hou et al, 2010;Sato et al, 2004). As shown in Figure 4, plants stored in light showed a marked high value in Pn accompanied by higher g S , Ci, and Tr than in darkness after 8 d of storage, which is in agreement with the changes in F v /F m and FPSII.…”

“…Kubota and Kozai (1994) found that broccoli plantlets stored in light could preserve their photosynthetic ability. Similar results were also observed in seedlings of Phalaenopsis (Su et al, 2001) and radiata pine (Mena-Petite et al, 2003). Compared with storage, the recovery of post-storage photosynthetic performance is very crucial for plants (Hou et al, 2010;Sato et al, 2004).…”

“…Compared with storage, the recovery of post-storage photosynthetic performance is very crucial for plants (Hou et al, 2010;Sato et al, 2004). A positive correlation was obtained after storage between photosynthetic rate and the new root growth in radiata pine seedlings (Mena-Petite et al, 2003). Chlorophyll fluorescence parameters were also closely related to the survival of Douglas fir seedlings in a greenhouse (Harper et al, 2010).…”

Physiological Advantages of Grafted Watermelon (Citrullus lanatus) Seedlings under Low-temperature Storage in Darkness

“…As mentioned, the reasons for the higher photosynthesis in grafted watermelon seedlings might be: 1) a higher carbohydrate reserve in the leaves of grafted seedlings contributed to photosynthesis; and 2) higher activities of antioxidant enzymes in the grafted seedlings scavenged the excess ROS, reduced the chlorophyll loss, and protected the photosynthetic system during storage. In addition, our previous study showed that the grafted ones had a stronger root system and quicker root regeneration after transplanting compared with the non-grafted watermelon seedlings (Ding et al, 2009), which could supply enough water to maintain a high photosynthetic rate (Mena-Petite et al, 2003).…”

Estratégias no uso da energia luminosa por plantas jovens de Genipa spruceana Steyerm submetidas ao alagamento

“…A determinação da fl uorescência da clorofi la a por ser uma técnica rápida, precisa e não destrutiva, tem sido usada para investigar danos causados por vários tipos de estresses sobre o aparato fotossintético (Oliveira et al 2002;Mielke et al 2003;Gonçalves et al 2005;Fernández 2006;Lavinsky et al 2007;Naumann et al 2008). Além disso, os parâmetros de fl uorescência da clorofi la a também têm se mostrado como ferramenta sensível capaz de diagnosticar a redução da assimilação de CO 2 e/ou destruição da estrutura fotossintética (Mena-Petite et al 2003). Sendo o fotossistema II responsável pelo fornecimento de energia para a fotossíntese, a avaliação de sua efi ciência mediante medidas da emissão da fl uorescência da clorofi la a pode ser usada como indicador dos danos causados pelo alagamento em espécies arbóreas.…”