To screen pesticides with improved disease control and increase the yield of konjac plant, we grew one-year-old konjac corms, determined the field control effect, growth indicators, photosynthetic indicators, and yield of konjac plants, and compared the results with those obtained after treatments with three kinds of antibiotic pesticides, three kinds of copper fungicides, chloroisobromine cyanuric acid, bismerthiazol, and water (as control). The results showed that the soft rot incidences in konjac plants after treatment with several pesticides were significantly lower than that of the control (CK). The control effects of tetramycin, copper succinate, and chloroisobromine cyanuric acid were high, the growth status of the plants treated with cuprous oxide, tetramycin, and copper succinate improved; the net photosynthetic rates of each pesticide treatment showed no significant difference from that of the CK, and the yield was the highest with copper succinate and tetramycin. This study demonstrated that certain copper fungicides or antibiotic pesticides can be used for the control of konjac soft rot, but their effects are different. The comprehensive comparison suggests that the effects of copper succinate and tetramycin are the best for the disease control and yield increase of konjac.

No abstract

To study the effects of shading level on the photosynthesis and corm weight of konjac plant, the chlorophyll fluorescence parameters, daily variation of relative electron transport rate (rETR), net photosynthetic rate (Pn), and corm weight of konjac plants under different treatments were measured and comparatively analyzed through covered cultivation of biennial seed corms with shade nets at different shading rates (0%, 50%, 70%, and 90%). The results showed that with the increase in shading rate, the maximum photochemical efficiency, potential activity, and non-photochemical quenching of photosystem Ⅱ (PSⅡ) of konjac leaves constantly increased, whereas the actual photosynthetic efficiency, rETR, and photochemical quenching of PSⅡ initially increased and then decreased. This result indicated that moderate shading could enhance the photosynthetic efficiency of konjac leaves. The daily variation of rETR in konjac plants under unshaded treatment showed a bimodal curve, whereas that under shaded treatment displayed a unimodal curve. The rETR of plants with 50% treatment and 70% treatment was gradually higher than that under unshaded treatment around noon. The moderate shading could increase the Pn of konjac leaves. The stomatal conductance and transpiration rate of the leaves under shaded treatment were significantly higher than those of the leaves under unshaded treatment. Shading could promote the growth of plants and increase corm weight. The comprehensive comparison shows that the konjac plants had strong photosynthetic capacity and high yield when the shading rate was 50%-70% for the area.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

No abstract