Abstract
Climatic changes have induced the spread of aridity in many parts of the globe. Eucalyptus plantations show wide variations in productivity due to several factors, including climatic changes. Therefore, Eucalyptus genotypes that can adapt to such conditions is very welcome. Thus, an evaluation was done by comparing the physiological responses of two Eucalyptus genotypes, tolerant and drought-sensitive. They were assessed in different stages of experimental period and the rate of chlorophyll and chlorophyll fluorescence (minimal fluorescence and maximal fluorescence) were recorded. The potential photosystem II (PSII) quantum efficiency was then calculated. A decline in the rate of total chlorophyll (values below 25) and in the minimal fluorescence (values below 190) in clone sensitive due to the water stress was observed, while an increase was noted in clone tolerant to aridity. A reduction in the maximal fluorescence and photochemical efficiency was recorded in the genotype not being irrigated, with an earlier and more severe effect being verified for the sensitive genotype with values below 300 and 0.40, respectively. The variables studied confirm that clone tolerant exhibits greater drought tolerance, thus indicating that the photochemical efficiency of photosystem II is a reliable tool that enables the nondestructive choice of genotypes naturally tolerant to water scarcity conditions. Key words: Abiotic stress, arid land plants, chlorophyll, ecophysiology, photochemical efficiency, tree drought tolerance, water deficit, water potential.
Highlights
Despite the fact that planted forests represent merely 7% of the world's forest cover, they make a vital contribution to forest services (Villar et al, 2011), the plants of the Eucalyptus genus
This study focused on the commercial clone sensitive of the Eucalyptus hybrid urograndis (Eucalyptus grandis vs. Eucalyptus urophylla), a genotype inefficient under water stress and clone tolerant of the hybrid Eucalyptus camaldulensis vs. E. grandis - a genotype model with high tolerance to water shortage
Emphasis was placed on day 11 of the stress, clear differences were noted in the chlorophyll content between the genotypes under the irrigated water regime, highlighting the clone tolerant
Summary
Despite the fact that planted forests represent merely 7% of the world's forest cover, they make a vital contribution to forest services (Villar et al, 2011), the plants of the Eucalyptus genus. Climatic changes over the recent decades have caused the proliferation of arid conditions across the world (Allen et al, 2010; Kirono et al, 2011), resulting in a growing demand for Eucalyptus genotypes adapted to such situations. Scientists believe that the escalating emissions of greenhouse gases is one of the main reasons causing the recent spurt in the global average temperature and alterations in the global hydrological cycle, including predictable sharp surges of aridity (Sterl et al, 2008). The need of the hour, is to identify parameters which can rapidly and efficiently distinguish between genotypes that are tolerant and susceptible to drought for forest development programs
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