Effect Of Soil Water And Nitrogen Fertilizer On Some Physiological Characters, Yield And Quality Of Pepper

Hot pepper variety (Dafang line pepper) in Guizhou was used in a pot culture experiment. Effects of nitrogen fertilizer rates on some leaf Physiological characters under soil progressive drought during Blossom ing-fruiting stage, yield and quality of red hot pepper fruit with three soil water content from survive after transplanting to the end of harvesting were studied. The main results were as follows:1.Leaf relative water content of nitrogen fertilizer treatments decreased all the time, leaf hold water power firstly increased then decreased under soil progressive drought. Leaf relative water content of nitrogen fertilizer treatments had no distinct difference, when soil relative water content was 80%Q. The descending range of leave relative water content was high N > low N > middle N, when soil relative water content was decreased from 80%Q to 40%Q. Leaf relative water content was Low N, middle N > high N, When soil relative water content was 50%Q, the difference was remarkable between high N and middle N. Leave hold water power of low N treatment was lower than high N and middle N treatments and there was no distinct different between high N and low N treatments, when soil relative water content was 80%Q or 60%Q. Leave hold water power of middle N treatment was higher than low N and high N treatments and there was no distinct difference between high N and low N treatments, when soil relative water content was 50%Q or 40%Q.2. The leaf chlorophyll content of nitrogen fertilizer treatments decreased all the time , The leaf chlorophyll content increased and they were significantly lower than no treatment after re-watering, the leaf chlorophyll content was always high N > middle N >low N. The descending range of leaf chlorophyll content was high N > middle N > low N, the chlorophyll a/b of nitrogen fertilizer treatments decreased, the descending range was low N > high N > middle N , when soil relative water content was decreased from 80%Q to 40%Q.3. SOD and POD activity firstly increased then decreased, the CAT activity descended all the time, meanwhile, cell Membrane Permeability and MDA content increased all the time under soil progressive drought, cell Membrane Permeability, MDA content, and POD activity were higher than no treatment, SOD and CAT activity were lower than no treatment after re-watering. SOD, POD and CAT activity of high N and middle N treatments were significantly higher than low N treatment under soil progressive drought and re-watering. SOD, POD and CAT activity of high N treatment decreased more quickly than middle N treatment under medium and serious drought, finally it was lower than middle N treatment, furthermore, SOD, POD and CAT activity of middle N was still higher than high N after re-watering. Cell Membrane Permeability and MDA content of high N and middle N treatments was clearly lower than high N treatment under soil progressive drought and re-watering. The descending range of Cell Membrane Permeability and MDA content was high N > middle N , when the soil relative water content was decreased from 60%Q to 40%Q. Cell Membrane Permeability and MDA content of high N treatment are higher than middle N treatment, when soil relative water content was 40%Q or 50%Q. The difference of Cell Membrane Permeability was significant difference both high N and middle N, Cell Membrane Permeability and MDA content of middle N was still higher than high N after re-watering.4. The proline content of nitrogen fertilizer treatments increased all the time, soluble sugar content and soluble protein content firstly increased then decreased under soil progressive drought, proline content, soluble sugar content were higher than no treatment, soluble protein content was lower than no treatment after re-watering. proline content, soluble protein content increased with the increase of nitrogen fertilizer rate under soil progressive drought, proline content of nitrogen fertilizer treatments was very significant difference and the difference of soluble protein content was significant difference both high N and low N treatments. Soluble sugar content of low N treatment increased quickly under medium drought and serious drought, finally it was higher than middle N treatment, but the difference was not significant.5. The nitrogen fertilizer rate and soil water content were significant effect on yield, some treatments were very significant difference, W₂N₁ (soil water low limit 60%Q, 0.2gN/kg dry soil) was the highest yield. Capsaicin content, vitamin C content of N₁ compared with N₀ and N₂ was significant difference, some treatments was very significant difference, dry matter content and soluble sugar content of nitrogen fertilizer rates were very significant difference , but capsaicin content and vitamin C content declined with the overuse of nitrogen fertilizer. Capsaicin content was significant difference , some treaments was very significant difference, the comparison of vitamin C content between W₃ and W₁ was significant difference under the same nitrogen fertilizer rate.