ABSTRACT
To determine the suitable planting density and row spacing of short-season cotton suitable for machine picking in the Yellow River Basin of China, we conducted a two-year field experiment in Dezhou during 2018-2019. The experiment followed a split-plot design, with planting density (82500 plants·hm-2 and 112500 plants·hm-2) as the main plots and row spacing (equal row spacing of 76 cm, wide-narrow row spacing of 66 cm+10 cm, equal row spacing of 60 cm) as the subplots. We examined the effects of planting density and row spacing on growth and development, canopy structure, seed cotton yield and fiber quality of short-season cotton. The results showed that plant height and LAI under high density treatment were significantly greater than those under low density treatment. The transmittance of the bottom layer was significantly lower than under low density treatment. Plant height under 76 cm equal row spacing was significantly higher than that under 60 cm equal row spacing, while that under wide-narrow row spacing (66 cm +10 cm) was significantly smaller than that under 60 cm equal row spacing in peak bolling stage. The effects of row spacing on LAI varied between the two years, densities, and growth stages. On the whole, the LAI under the wide-narrow row spacing (66 cm+10 cm) was higher, with the curve declining gently after the peak, and it was higher than that in the two cases of equal row spacing in the harvest time. The change in transmittance of the bottom layer presented the opposite trend. Density, row spacing, and their interaction had significant effects on seed cotton yield and its components. In both years, seed cotton yield was the highest (3832 kg·hm-2 in 2018, 3235 kg·hm-2 in 2019) under wide-narrow row spacing (66 cm+10 cm), and it was more stable at high densities. Fiber quality was less affected by density and row spacing. To sum up, the optimal density and row spacing of short-season cotton were as follows: density with 112500 plants·hm-2 and wide-narrow row spacing (66 cm+10 cm).
Subject(s)
Rivers , Seeds , Seasons , Biomass , GossypiumABSTRACT
In this study, the cytotoxicity of sliver nanoparticle-doped chitosan composite films (AgNPs/CS) was investigated in vitro. In this slow-release system, the doped silver nanoparticles (AgNPs) might modify both the surface properties of the matrix and the ion environment of the surrounding fluid via slow-release, determining the dominant mechanism is of interest. Here, AgNPs (average size is 25 nm) were doped into chitosan (CS) films by mechanical mixing to form a slow-release system. The surface properties and stabilities of the films and the Ag-releasing behavior were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectrophotometry, and a weight loss method. The morphology of adhered cells and the survival rate (obtained by both MTT and CCK-8 assays) of human umbilical vein endothelial cells (HUVEC) were employed to describe the cytotoxicity. Using statistical analysis, the following conclusions can be made: the doped AgNPs dispersed in the CS matrix with a polycrystalline structure. During the early erosion, a small amount of debris peeled off and became suspended in the fluid. After that erosion, the composite film became relatively stable, and the doped Ag was slowly released into the fluid. In comparison with the released Ag (either in the peeled debris or dissolved in the fluid), Ag immobilized in the AgNPs/CS films shows a more significant influence on cell adhesion and subsequent proliferation. Film thickness and AgNP content show a synergistic effect on the survival rate of the cell, with the AgNPs content being the key factor.
