Evandro Manoel da Silva

Production of guava rootstock grown with water of different salinities and doses of nitrogen

The scarcity of good-quality water and the occurrence of low-fertility soils are limiting factors in irrigated agriculture, especially in arid and semi-arid regions, which leads to the use of salt water and nitrogen fertiliser as alternatives for agricultural production in these regions. The aim of this work therefore, was to evaluate growth, biomass production and rootstock quality in the guava ‘Crioula’ under salt stress and doses of nitrogen fertiliser in a protected environment at CCTA/ UFCG. The experimental design was of randomised blocks in a 5 x 4 factorial scheme, with four replications. The treatments consisted of a combination of five levels of electrical conductivity of the irrigation water (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four doses of nitrogen (70, 100, 130 and 160% of the recommended dose for guava seedlings). The dose of 541.1 mg N dm-3 soil (70% of the recommended N) stimulated growth, the accumulation of shoot biomass, and the quality of the guava ‘Crioula’ rootstock. Irrigation with an ECw greater than 0.3 dS m-1 had a negative effect on the absolute growth rate of the stem diameter, shoot dry matter, root to shoot ratio, and the Dickson quality index. Nitrogen fertiliser at 70 and 100% of the recommended level of N reduced the effect of irrigation water salinity on the relative growth rate of the stem diameter in the guava rootstock.A escassez de agua de boa qualidade e a ocorrencia de solos com baixa fertilidade sao fatores limitantes para a agricultura irrigada, principalmente em regioes aridas e semiaridas, o que induz a utilizacao de aguas salinas e adubacao nitrogenada como alternativas para a producao agricola nessas regioes. Desse modo, objetivou-se avaliar o crescimento, producao de fitomassa e qualidade de porta-enxerto de goiabeira ‘Crioula’ sob estresse salino e doses de adubacao nitrogenada, em condicoes de ambiente protegido no CCTA/UFCG. O delineamento estatistico foi o de blocos casualizados em esquema fatorial (5 x 4), com quatro repeticoes. Os tratamentos consistiram da combinacao de cinco niveis de condutividade eletrica da agua de irrigacao (0,3; 1,1; 1,9; 2,7 e 3,5 dS m-1) e quatro doses de nitrogenio (70, 100, 130 e 160% de N da dose recomendada para cultivo de mudas de goiabeira). A dose de 541,1 mg de N dm-3 de solo (70% de N recomendada) estimulou o crescimento, o acumulo de fitomassa na parte aerea e a qualidade dos porta-enxertos de goiabeira ‘Crioula’. Irrigacao com CEa acima de 0,3 dS m-1 afetou negativamente as taxas de crescimento absoluto do diâmetro do caule, fitomassa seca da parte aerea, relacao raiz/parte aerea e indice de qualidade de Dickson. A adubacao nitrogenada nas doses de 70 e 100% de N recomendada reduziu o efeito da salinidade da agua de irrigacao sobre a taxa de crescimento relativo do diâmetro do caule de porta-enxertos de goiabeira.