BRITO, M. E. B.; http://lattes.cnpq.br/8351301033142826; BRITO, Marcos Eric Barbosa.
Résumé:
This work was carried out aiming to evaluate the salt tolerance of citrus
genotypes (varieties and hybrids) in the formation stage of seedlings under greenhouse
conditions and in the initial growing under field conditions. Two experiments were
conducted: one in a greenhouse located in the UFCG, Campina Grande Campus; and another
in an experimental area of 'Tabuleiro' Farm located in the municipality of Pombal, State of
Paraíba. In the greenhouse experiment, three factors were investigated: five levels of salinity
of the irrigation water and twelve genotypes of citrus rootstocks grafted with two varieties -
acid lime tree 'Tahiti [Citrus latifolia (Yu Tanaka) Tanaka] 'CNPMF 2001' selection, and
grapefruit (C. Parididi) 'Star Ruby'. The statistical design was in randomized blocks with
three replications and the experimental unit consisted of nine plants. The rootstocks were
formed using polyethylene tubes (288 mL capacity), with their subsequent transplanting
(150 days after sowing) to plastic bags (3400 mL capacity) with 12 cm diameter and 30 cm
height. After grafting, the plant growth was evaluated and, after growth of grafts, the most
promising six combinations (scion/rootstock) were selected, using as criteria the percentage
of survival of the plants with increasing salinity. In the field experiment, the six selected
combinations of scion/rootstocks were investigated under three different managements of
water salinity: (1) Control management - plants were exposed to water with electrical
conductivity (ECw) of 0.8 dS m"1 during the seedlings formation and in the field; (2) - plants
irrigated with water with ECw of 0.8 dS m"1, during the seedlings formation, began to
receive water with ECw of 2.4 dS m"1, at field conditions; (3) - plants were subjected to
irrigated with water with ECw of 2.4 dS m"1, in the seedlings formation and in the field.
Variables of growth and physiological parameters were evaluated under field conditions, at
60, 90 and 210 days after plant transplantation. The studied variables were subjected to the
'F' test comparing averages by Tukey's test or Scott-Knott. It was observed a greater growth
in the formation stage of genotypes rootstocks G3 (TSKC x CTC25 - 010) and G4 (TSKFL
x CTC13 - 025), followed by Gl (lime tree "Rangpur Santa Cruz"), G5 (Hybrid Trifoliate -
069) and G12 (lime tree 'Volkameriano'), and they, also, were less affected by increasing
salinity. After grafting, especially with increasing salinity, the rates of survival involving
combinations of rootstocks with G3 and G4 with the grapefruit or the lime tree 'Tahiti' were
low; the best combinations were observed in G l , G5 and G12 with both treetop varieties, 'Tahiti' and 'Star Ruby'. Under field experiment, higher growth rates and better
physiological behavior were observed in lime tree 'Rangpur' grafted with 'Star Ruby' or
'Tahiti' when irrigated with saline water.