Impact of biostimulant and saline water on cape gooseberry (Physalis peruviana L.) in Brazil

Production of Physalis peruviana L. has gained prominence in Northeastern Brazil. However, salinity limits the crop development in the Brazilian semiarid. Thus, this research aimed to evaluate the application of Acadian® biostimulant as mitigant of the deleterious effects of salinity on growth and gas exchange of P. peruviana plants. The experiment was combining different electrical conductivity of irrigation water (0.50, 1.23, 3.00, 4.44, and 5.50 dS m^-1) and biostimulant doses (0.00, 1.45, 5.00, 8.55, and 10.00 mL L^-1). The main variables evaluated were plant height, stem diameter, number of leaves, root length, leaf area, specific leaf area, leaf area ratio, absolute and relative growth rate for plant height, and gas exchange. Experimental results showed that an increase in electrical conductivity of irrigation water had negatively affected the growth components and gas exchange in P. peruviana. Also, the application of seaweed-based biostimulant improves the photosynthetic capacity (43.3%), reduces transpiration rate (26.5%) and water loss by this process, further it attenuated the deleterious effects of salinity on specific leaf area, leaf area ratio, and stomatal conductance. To further elucidate the effectiveness of biostimulant application as a mitigant of salt stress, research aimed at the biochemical and enzyme activities of the plant's antioxidant system should be conducted to better understand this process.

Estimativa da área foliar de Mesosphaerum suaveolens a partir de relações alométricas

Resumo A determinação da área foliar é de fundamental importância em estudos ecofisiológicos que buscam entender a relação planta-ambiente. Objetivou-se com esta pesquisa determinar uma equação alométrica que permita estimar a área foliar de Mesosphaerum suaveolens a partir de medidas lineares do limbo foliar (comprimento e/ou largura). Coletaram-se 900 limbos foliares aleatórios de diferentes formas e tamanhos, em uma área de Caatinga antropizada, localizada no município de Santa Luzia, estado da Paraíba, nordeste do Brasil. Para a construção das equações alométricas utilizaram-se os seguintes modelos de regressão: linear, linear sem intercepto, quadrático, cúbico, potência e exponencial. O modelo linear sem intercepto utilizando o produto entre comprimento e largura (C.L) foi o mais indicado para estimar a área foliar de M. suaveolens, com maior coeficiente de determinação (R2) e índice de concordância de Willmott (d), menor erro absoluto médio (MAE), critério de informação de Akaike (AIC) e raiz do quadrado médio do erro (RQME), e índice BIAS mais próximo de zero (R2 = 0,9971; d = 0,9989; MAE = 0,422; AIC = 2094,69; RQME = 0,770; BIAS = -0,0105). A área foliar de M. suaveolens pode ser estimada satisfatoriamente pela equação AF = 0,6787*(C.L).

Morphophysiological aspects of young Calotropis procera plants submitted to different shading levels

The silk flower (Calotropis procera) is a plant found practically in the whole Northeast region of Brazil and can be used for several purposes. However, its morphophysiological characteristics may be influenced by the degree of brightness. This study aimed to evaluate the morphophysiological behavior of silk flower under different shading levels. The experiment was carried out in a greenhouse belonging to the Federal University of Paraíba, Areia, Paraíba, Brazil. The experimental design was completely randomized, with five treatments and eight repetitions. The treatments used were different shading levels: 0 (full sun), 30%, 50%, 70% and 90% of shading. Growth characteristics, morphofunctional attributes, gas exchange and chlorophyll a fluorescence were evaluated. The data were submitted to analysis of variance by the F-test, and in cases of significance, a polynomial regression analysis was performed. The best result for the plant height was found at the shading level of 68.4%. Gas exchange and chlorophyll a fluorescence variables presented higher values in the levels of higher light availability. Silk flower plants grow best under full sun conditions. Shading negatively affects the gas exchange and quantum efficiency of silk flower plants.