Influence of Root Interaction in Eucalyptus Clones under Two Environmental Conditions

Abstract

The global climate changes likely will alters water availability to plants. This makes relevant to investigate how plants manage water use. Competition for limited resources is constant in plant life. Competition for water occurs among roots and is related with the ability of plants to discriminate self from nonself roots. Even clones have such ability, allowing them to compete, or not, depending on resources availability. Therefore, we investigated how self/nonself discrimination ability influences the establishment of interaction among cloned plants under two water regimes.An experiment was performed with the urograndis hybrid ‘I 144’ (Eucalyptus grandis & Eucalyptus urophila) from a unique clonal garden. Roots were pruned, letting only two similar roots per plant. They were arranged in two types of triplets: self and nonself ones (Figure 1). The plants were grown during 60 days under two different water regimes: well-watered (WW) and water-deficit (WD). Biometrics averages were compared by two-way-ANOVA, and Tukey test (p<0.05).Self-WD decreased total biomass (26%), root biomass (37%), leaf biomass (28%) and leaf number (16%) compared with self- WW. Non-self-WD decreased leaf number in 24%, compared with non-self-WW (Table 1).Non-self-WW decreased total biomass, leaf biomass, stem biomass, leaf area by 24%, and height (9%), compared with self-WW. Non-self-WD decreased branch mass (13%) and leaf number (29%), compared with self-WD.The root interaction influenced the behavior of plants, as demonstrated by differentiated development between self and nonself treatments. There was competition in non-self-WW triplets, since plants accumulated less total biomass than self-WW. There was no competition in non-self-WD, because plants accumulated the same total biomass than self-WD. Actually, we suggest that these plants may have collaborated. This behavior was already reported to clones under resource limitations. Switch between competition and collaboration may be a frequent response of plants to global climate change depending on their neighborhood.