Below and aboveground growth of four Eucalyptus grandis x Eucalyptus urophylla and one Eucalyptus camaldulensis x Eucalyptus spp clones identified as 0063, 0321, 1250, 1260 and 1277, were studied in the field under varying water availability. The objective of the study was to select eucalypt genotypes to be planted in sites with varying soil water availability. The experiment was set in Northeastern Brazil, Inhambupe, Bahia (Latitude - 11º47'00''S; Longitude - 38º21'00''W and Altitude - 154 m), with mean annual rainfall of 950 mm. Two levels of irrigation were applied six months after the seedlings have being planted in the field: (a) irrigated when weekly rainfall was lower than 10 mm and, (b) non-irrigated - plants received water only from rainfall. Root distribution and biomass were determined six months after planting, just before the irrigation treatment started, in order to characterize root growth of each clone. Height and diameter at breast height (DBH) were measured at the age of 38 months. There was no significant difference (P=0.05) in height growth at this age between irrigation treatments, but there were differences in growth among clones: clone 1260 was significantly taller than the others. DBH and volume were significantly larger for irrigated plants; however, there was a tendency of clone 1277 to maintain growth even under drought. Clone 1260 followed by the 0321 presented the highest volume by the age of 38 months in both dry and wet soil conditions. The growth rate of clone 1277 is lower than for clones 1260 and 0321, but, due to its root production and distribution deep in the soil profile, it survives and grows in sites with low soil water availability. Clone 1250 showed great reduction in volume when under water stress, probably due to its poor root growth, i.e., this clone is not recommended for dry sites.
Eucalypt clones; root and aboveground growth and genotype selection to drought
