ABSTRACT Among the main problems that compromise the development of forest species are water and salt stresses, especially in the early stages of development, when seedlings are more sensitive. Thus, the objective of this study was to evaluate the morphophysiological and biochemical changes in Enterolobium contortisiliquum seedlings subjected to abiotic stresses. The experimental design was randomized complete blocks (RCB), composed of five treatments, with four replicates, and the experimental plot consisted of twenty plants. From the 31st day after sowing, when the seedlings reached approximately 15 cm in height, they began to receive the treatments, which consisted of different levels of electrical conductivity of irrigation water (0.3; 2; 4; 6; 8 dS m-1) for salt stress and periods of water restriction (0; 4; 8; 12 and 16 days without irrigation) for water stress. The traits evaluated were: plant height, root length, stem diameter, number of leaves, leaf area, total dry matter, Dickson quality index, height/shoot dry matter ratio, total soluble sugars, starch, total amino acids and proline. An increase in the electrical conductivity of irrigation water and days without irrigation compromised the development of E. contortisiliquum seedlings, which was intensified from 2 dS m-1 and four days without irrigation for salt and water stresses, respectively. The mechanism of survival of E. contortisiliquum to abiotic stresses involves reduction in the growth and quality of seedlings, with activation of biochemical defense mechanisms of the species.

ABSTRACT The objective was to verify if the primary root emission can be recommended as a vigor test for soybean seeds. For this, five lots of varieties ANTA 82, NA7337 and BRS1074IPRO were evaluated by first count, germination, emergence, emergence speed index and tetrazolium tests. In the root protrusion test at 20, 25 and 30 ºC, two evaluation criteria were adopted: primary root emission precocity index (PREPI) and percentage of seeds that emitted the primary root (PRE). The seeds counted were those with a primary root equal to or greater than 2 mm, every 12 h from the installation of the test until 120 h. The design was completely randomized and means were compared, within each evaluation time, using the Scott-Knott test at 5% probability. Pearson’s linear correlation was performed for PREPI and PRE with emergence. PREPI was not considered efficient. For the PRE, at 20 ºC, there was a correlation at 72 h, for the three varieties. At 25 ºC there was a correlation for a period of 36 h for ANTA 82 and NA7337 and 60 h for BRS1074IPRO. At 30 ºC there was a correlation in the time of 36 h for the three cultivars. Considering that speed in obtaining results is important in vigor tests, it is concluded that primary root emission for 36 h after installing the test at 30 ºC is recommended as a vigor test in the quality control of soybean seeds.

ABSTRACT: The boundary line is a method frequently used to assess the nutritional status of plants when the relationship between the variables under analysis is influenced by other interacting factors. The objective of this study was to propose and test the boundary line model to estimate the nutrient sufficiency range and nutritional status of irrigated muskmelon. The lower and upper limits of the sufficiency range were calculated as a basis for assessment of the nutritional status of muskmelon. Leaf material was collected from 70 muskmelon crop areas in northern Brazil. The nutrient (N, P, K, Ca, Mg, S, Fe, Zn, Mn, B, and Cu) concentrations in the leaf tissue and the respective fruit yield of each area were measured. The proposed model to estimate the boundary line allowed estimation of the sufficiency range of nutrients for irrigated muskmelon. The main growth-limiting factors of muskmelon due to nutritional deficiency were P > N = K, and those caused by nutrient excess were N > Zn = Cu.

Este estudo objetivou avaliar o efeito do fertilizante orgânico no crescimento de raiz e da parte aérea do meloeiro em função de graus dias acumulado. Foi instalado um experimento em vasos, em delineamento experimental em blocos casualizados com quatro repetições em esquema fatorial 2x6, referente a presença e ausência de fertilizante orgânico e seis épocas de amostragens (7; 14; 21; 28; 35 42 dias), totalizando 48 parcelas experimentais. Para cada amostragem determinou-se número de folhas (NF), área foliar (AF), matéria seca de raiz (MSR) e matéria seca da parte aérea (MSPA). A taxa de crescimento absoluto (TCA) divergiu em função da adubação para as diferentes características avaliadas e na presença do fertilizante orgânico, verificou-se que as somas calóricas para se obter as maiores TCAmax foram maiores nos tratamento que não receberam o fertilizante orgânico.

This study aimed to evaluate the effect of organic fertilizer on root and shoot growth in the melon as a function of accumulated growing degree days. An experiment was set up in pots, in a randomized block design, with four replications and a 2x6 factorial arrangement, corresponding to the presence and absence of organic fertilizer, and six sampling dates (7; 14; 21; 28; 35 and 42 days), giving a total of 48 plots. For each sample, the number of leaves (NL), leaf area (LA), root dry matter (RDM) and shoot dry matter (SDM) were determined. The absolute growth rate (AGR) differed for those traits analysed according to the type of fertilisation used and the presence of organic fertilizer, it was found that the caloric totals required to get the highest AGR were higher in those treatments that received no organic fertilizer.