Emergência de sementes de cajazeira e produção de mudas sob estresse salinos e fontes potássicas.

Abstract

The cajá culture has great potential for the semiarid Northeast of Brazil, however, its production is limited by the germination processes, in turn, it interferes in the production of seedlings for the formation of commercial orchards, therefore, its production consists only of stratification, otherwise, is that in the semi-arid region, there is an excess of salts in the water used for irrigation, which leads to a reduction in crop production due to osmotic and ionic effects. In this sense, the objective was to evaluate the emergence in the function of the storage and emergence of seeds to break dormancy and growth, photosynthetic pigments, and phytomass, using the function of the break of dormancy and storage of seeds and sources of potassium in the mitigation of saline stress in cajazeira tree seedlings. The research was carried out in two stages, in the first stage, the experimental design was adopted in randomized blocks, in a 3 × 2 factorial schemes related to three types of scarifications (without scarification, scarification of the distal part, and scarification of the distal and proximal part of the seed) and two forms of storage (freezer storage for two years and seeds of the year), with four replications, 23 seeds per plot, totaling 552 experimental units. In the second stage, an experimental design was used in randomized blocks with a 5 × 3 factorial scheme, corresponding to five levels of electrical conductivity of irrigation water (0.3, 1.3, 2.3, 3.3 and 4.3 dS. m-1) and three sources of potassium fertilization (potassium chloride, potassium sulfate, and potassium nitrate) with three replicates and two plants per plot, totaling 90 experimental units. The cajazeira seeds of the year resulted in a higher index of emergence speed and plant height, while seeds stored for two years had a larger stem diameter than the plants. The scarification of the distal and proximal parts of the cajazeira nut seeds increased the emergence percentage and emergence speed index. Irrigation with water with an electrical conductivity of 4.3 dS. m-1 associated with KCl fertilization reduces growth, photosynthetic pigments, and phytomass, and increases the extravasation of electrolytes and carotenoids. The deleterious effects of saline stress on cajazeira seedlings are not attenuated by fertilization with potassium sources.