Study On Plastic Mulched Cultivation And Feeding Value Of Fodder Sugar Beet(Beta Vulgaris)in Alpine Region

1. In alpine region with the altitude of 2960m ASL, when the sugar beet was cultivated with plastic mulch, the soil temperature and humidity can be increased, the organic matter, total nitrogen, available nitrogen, total phosphorus in soil can be also improved, and the weeds in the field can be inhibited as well during whole growing period of the crop. With the increase of the mulch thickness, the effect got more and more remarkable. Compared with the control (without mulch), the accumulative temperature of soil within 0?5 depth were improved 1630. 80C, 2023.40C and 3004.90C in whole growing period, equaling to l.90C, 2.S0C and 3 .40C per day on average when covered with 0.006mm, 0.008mm and 0.014mm plastic mulches (treatments), and the humidity, organic matter, total nitrogen, available nitrogen and total phosphorus in soil were increased 1.1 6?.45 unit percent, 0.004. i36unit percent, 0.049?.090 unit percent, 0.004-0.015 unit percent and 0.005?.0 14 unit percent respectively under the condition of mulch covering during 151 days growing period of the fodder sugar beet. 2. The phonology of the crop cultivated with the plastic mulch was 15d ahead of the control, and it showed some variation among the plastic mulches of different thickness, that of the plant with 0.0 14 mm was 2-4 d earlier than 0.008mm, 3? d earlier than 0.006mm, and that of the plant with 0.008mm was 1? d earlier than 0.006mm. The leaf area index(LAI), growth rate of the crop with the mulch were higher than the control. There were not significant difference between the photosynthesis of the treatment and that of the control (P>0.05). 3. Daily dynamic of the photosynthesis (Pn) of the sugar beet clearly showed double picks at 10:00 a.m. and 14:00 p.m., and the second pick was a bit lower than the first, the bottom appeared at 12:00, which can be explained as 搕he Noon Break?of photosynthesis. The daily dynamic of relative humidity (RH) of the sugar beet completely showed same tendency. But that of the leaf temperature (TI) was totally difference, with only one peak at 10 a.m. 4. The DM yields of the aboveground part (stem and leaf) and the underground part (root) of fodder sugar beet with plastic mulch were significantly higher than the control (P<0.05 or P<0.01). The average yield (aboveground and underground in total) of Lc-1 sugar beet(variety) with 0.006mm, 0.008mm and 0.014mm plastic ? mulch were 19.54t1hn9, 21.84 tihni2, and 24.07 f/bin2 respectively, and that of their control was only 5.77 t/hn9. The yields of Red sugar beet(another variety) were ? 18.12 t/hm2, 19.27 t/hin2 and 30.59 t/hm2 accordingly, that of their control was only 2.35 t/hm2 The conversion efficiencies of solar energy by the underground part (root) of Lc-1 sugar beet with 0.006mm, 0.008mm and 0.014mm plastic mulch were 0.46%, 0.500/o and 0.55% individually, and that of the control was 0.11%, with non-significant difference (P>0.05) among the treatments, and significant difference between the treatment and the control (P<0.05 or P<0.01). The conversion efficiencies of solar energy by the aboveground parts (stem and leaf) of Lc-1 were 0.77%, 0.70%, 0.6 1% accordingly, and that of the control was 0.31%, with the same statistical results as the underground part (root). 5. The average contents of nutrients in the underground part (root) and aboveground parts (stem and leaf) of fodder sugar beet harvested in alpine r...