(untitled) (Nativa, 2019)
O trabalho objetivou avaliar os efeitos do excesso de ferro sobre a emergência e desenvolvimento inicial de genótipos de porta-enxertos cítricos. Adotou-se delineamento em blocos casualizados (DBC), em fatorial 5x2, com cinco porta-enxertos e dois substratos, repetidos quatro vezes, com parcela útil de 15 recipientes. Os genótipos consistiram do limoeiro ‘Cravo Santa Cruz’; citrandarins ‘Riverside’, ‘San Diego’ e ‘Índio’, além de, tangerineira ‘Sunki Tropical’, cultivados com ou sem óxido de ferro no substrato. Analisaram-se as porcentagens de emergência (PE) e calculou-se o índice de velocidade de emergência (IVE). Realizaram-se biometrias aos 30, 60 e 90 dias após a semeadura (DAS), mensurando-se a altura (H) e diâmetro de caule (D) das plântulas, determinando-se massa fresca (MV) e seca (MS). O excesso de ferro induziu subdesenvolvimento, e até mortalidade de plântulas já emergidas, o que refletiu diretamente nos resultados, porém, todos os genótipos apresentaram emergência superior a 75%, destacando-se o citrandarin ‘San Diego’, com maior altura e caule mais espesso, e o citrandarin ‘Riverside’ com maior sensibilidade ao estresse, registrando os menores valores. O citrandarin ’San Diego’ demonstrou tolerância o estresse e desenvolveu-se satisfatoriamente, necessitando estudos que avaliem a manutenção das características inferidas em combinação com a cultivar copa. Palavras-chave: ambiente protegido, citricultura, enxertia, estresse, mudas. EXCESS OF IRON ON THE DEVELOPMENT OF CITRUS ROOTSTOCKS ABSTRACT: The objective of this work was evaluated the effects of iron excess on the emergence and initial development of citrus rootstock genotypes. A randomized complete block design (DBC), factorial 5x2, with five rootstocks and two substrates, repeated four times, with useful plot of 15 containers was adopted. Genotypes consisted of the ’Santa Cruz’ Rangpur lemon; ’Riverside’, ’San Diego’ and ’Indio’ citrandarins, as well as ’Sunki Tropical’ tangerine, grown with or without iron excess in substrate. The percentages of emergency (PE) were analyzed and the rate of emergency (IVE) was calculated. Biometry was performed at 30, 60 and 90 days after sowing (DAS), by measuring the height (H) and stem diameter (D) of the seedlings, determining fresh (MV) and dry mass (DM). The excess of iron induced underdevelopment, and even mortality of already emerged seedlings, which reflected directly in the results, however, all genotypes presented an emergency higher to 75%, standing out ’San Diego’ citrandarin, with greater height and more stem thick, and the ‘Riverside’ citrandarin with greater sensitivity to stress, registering the lowest values. ’San Diego’ citrandarin demonstrated stress tolerance and developed satisfactorily, requiring studies that evaluate maintenance of inferred characteristics in combination with cultivar canopy. Keywords: protected environment, citriculture, grafting, stress, seedlings.