The development of smartphones, specifically their cameras, and imaging technologies has enabled their use as sensors/measurement tools. Here we aimed to evaluate the applicability of a fast and noninvasive method for the estimation of total chlorophyll (Chl), Chl a, Chl b, and carotenoids (Car) content of soybean plants using a smartphone camera. Single leaf disc images were obtained using a smartphone camera. Subsequently, for the same leaf discs, a Chl meter was used to obtain the relative index of Chl and the photosynthetic pigments were then determined using a classic method. The RGB, HSB and CIELab color models were extracted from the smartphone images and correlated to Chl values obtained using a Chl meter and by a standard laboratory protocol. The smartphone camera was sensitive enough to capture successfully a broad range of Chl and Car contents seen in soybean leaves. Although there was a variation between color models, some of the proposed regressions (e.g., the S and b index from HSB and Lab color models and NRI [RGB model]) were very close to the Chl meter values. Based on our findings, smartphones can be used for rapid and accurate estimation of soybean and Car contents in soybean leaves., J. P. G. Rigon, S. Capuani, D. M. Fernandes, T. M. Guimarães., and Obsahuje bibliografii
In order to evaluate the effect of static magnetic field (SMF) on morphological and physiological responses of soybean to water stress, plants were grown under well-watered (WW) and water-stress (WS) conditions. The adverse effects of WS given at different growth stages was found on growth, yield, and various physiological attributes, but WS at the flowering stage severely decreased all of above parameters in soybean. The result indicated that SMF pretreatment to the seeds significantly increased the plant growth attributes, biomass accumulation, and photosynthetic performance under both WW and WS conditions. Chlorophyll a fluorescence transient from SMF-treated plants gave a higher fluorescence yield at J-I-P phase. Photosynthetic pigments, efficiency of PSII, performance index based on absorption of light energy, photosynthesis, and nitrate reductase activity were also higher in plants emerged from SMF-pretreated seeds which resulted in an improved yield of soybean. Thus SMF pretreatment mitigated the adverse effects of water stress in soybean., L. Baghel, S. Kataria, K. N. Guruprasad., and Obsahuje bibliografii
Intercropping, a traditional and worldwide cropping practice, has been considered as a paradigm of sustainable agriculture based on complementary mechanisms among different crop species. Soybean (Glycine max) is widely relay intercropped about 60 days before maize (Zea mays) harvest in Southwest China. However, shade caused by tall maize plants may be a limiting factor for soybean growth at a seedling stage. In field research, we studied the ecophysiological responses of two widely cultivated soybean varieties [Gongqiudou494-1 (GQD) and Gongxuan 1 (GX)] to maize shading in a relay intercropping system (RI) compared with monocropped soybean plants (M). Our results showed that soybean seedlings intercropped with maize exhibited significantly downregulated net photosynthetic rate (PN) (-38.3%), transpiration rate (-42.7%), and stomatal conductance (-55.4%) due to low available light. The insignificant changes in intercellular CO2 concentration and the maximum efficiency of PSII photochemistry suggested that the maize shading-induced depressions in PN were probably caused by the deficiency of energy for carbon assimilation. The significantly increased total chlorophyll (Chl) content (+27.4%) and Chl b content (+52.2%), with lowered Chl a/b ratios (-20.5%) indicated soybean plants adjusted their light-harvesting efficiency under maize shading condition. Biomass and leaf area index (LAI) of seedlings under RI decreased significantly (-78.7 and -71%, respectively) in comparison with M. Correlation analysis indicated the relative reduction in biomass accumulation was caused by the decline in LAI rather than PN, it affected negatively the final yields of soybean (32.8%). Cultivar-specific responses to maize shading were observed in respects of LAI, biomass, and grain yield. It indicated that GX might be a better cultivar for relay intercropping with maize in Southwest China., B. Y. Su, Y. X. Song, C. Song, L. Cui, T. W. Yong, W. Y. Yang., and Obsahuje bibliografii
We studied the effect of arbuscular mycorrhizal (AM) fungus, Glomus constrictum (Trappe), and soil phosphorus (P) on
gas-exchange parameters, growth, and nutrition of soybean plants grown in pots with sterilized soil. Two contrasting concentrations of KH2PO4, i.e. no added and 0.5 g(P) kg-1(soil), were used. Addition of soluble phosphate increased all growth parameters, P and N concentrations, and most of the studied photosynthetic parameters of both the mycorrhizal and nonmycorrhizal plants. The mycorrhizal inoculation significantly increased plant growth responses, P and N concentrations in shoot and root tissues, acid and alkaline phosphatase activities, and total soluble proteins in root tissues compared with the nonmycorrhizal plants. The stimulations were related to the level of the mycorrhizal colonization in the root tissues. The mycorrhizal plants showed significantly higher net photosynthetic rate, stomatal conductance, and transpiration rate than those of nonmycorrhizal plants, especially in soil without added P. The phosphate addition to soil reduced generally the percentage of the mycorrhizal colonization in the root tissues, and consequently the mycorrhizal benefits. In general, growth, nutrition, and photosynthetic parameters of the soybean plants showed a high degree of dependency on the mycorrhizal fungus in nonfertilized soil when compared with the soil fertilized with P. This study confirmed that AM colonization could improve growth and nutrition of the soybean plant through increasing photosynthesis in leaves, particularly at low P in soil., G. M. Abdel-Fattah, A. A. Asrar, S. M. Al-Amri, E. M. Abdel-Salam., and Obsahuje bibliografii