Salt tolerance during the seedling production stage of Catharanthus roseus, Tagetes patula and Celosia argentea

Resumo

The guarantee of water supply for irrigated agriculture in the semi-arid region must necessarily involve the use
of lower quality water, such as brackish water. The objective of the present work was to evaluate the tolerance to salinity of
the ornamental species Catharanthus roseus, Tagetes patula and Celosia argentea, using different methods. The experiment
was conducted in a randomized block, arranged in a 10 x 3 factorial scheme, corresponding to 10 saline concentrations of
irrigation water (ECw 0.5; 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0; 5.0 and 6.0 dS m-1) and 3 ornamental species. Four salinity tolerance
assessment methods were tested, using relative values or percentages of reduction in quantitative and qualitative analyses. The
different methods show the highest sensitivity to salinity of C. roseus, in the seedling production stage, compared to T. patula
and C. argentea species. The methods of threshold salinity and ORN index led to similar results in terms of classification of
salt tolerance, with C. roseus classified as sensitive and T. patula and C. argentea as moderately sensitive. The method of
Fageria (1985) allowed good separation of the species, with tolerance limits of 1.5, 2.5 and 3.5 dS m-1, respectively for C.
roseus, T. patula and C. argentea. It is obvious from the comparison with literature data that the seedling production stage is
more sensitive to salt stress, and it is necessary to carry out new studies aimed at attenuating the effects of stress at this stage,
through the use of management techniques.