Study On The Effects Of Temperature Rise By Mulching On The Growth And Development Of Rape And Rice

It's a undeniable fact that global climate changed especially climate became warmer during the past years, which has imposed great effects on agricultural production. In order to deal with the influence to crop production, this research studied the effects to rape and early rice's growth and development by adopting 3 methods respectively being plastic mulch on soil(S), plastic mulch on plant(P), plastic mulch on soil and plant(SP), which were processed at early growth stages(EGS), late growth stages(LGS), and whole growth period(WGP) to simulate the greenhouse effect. The main results were as follows:1 The effects of mulch treatments to temperature changes.(1) During the rape period, the results showed that,compared with CK, plastic mulch on soil and plant and plastic mulch on plant could raise the air temperature and daily temperature change, especially the former. At early growth stages, the average of air daily temperature change of each method were plastic mulch on soil and plant 9.46℃,plastic mulch on plant 7.99℃,plastic mulch on soil 5.9℃;At late growth stages, each changed to 10.23℃,9.04℃,7.13℃. For the soil temperature, plastic mulch on soil and plant showed the highest at EGS, CK showed the highest at LGS, and changed with outside climates. The highest soil daily temperature change showed in CK, then in plastic mulch on plant. The average of soil daily temperature change at EGS of each treatments was CK 4.81℃,plastic mulch on soil and plant 3.39℃,plastic mulch on plant 4.22℃,plastic mulch on soil 3.74℃;and at LGS it was CK 5.76℃,plastic mulch on soil and plant 4.50℃,plastic mulch on plant 5.15℃,plastic mulch on soil 4.90℃.(2) During the early rice period, coverage of plant part could increase the air daily temperature change, the highest air daily temperature change showed in plastic mulch on soil and plant, the average of air daily temperature change was 9.334℃;the second in plastic mulch on plant with the average of 8.653℃;CK showed the lowest change with 6.409℃of average. The differences of soil daily temperature change were less significant between treatments, the highest soil daily temperature change existed in CK with the average of 5.064℃;and the lowest exist in plastic mulch on soil with average of 3.391℃;the average temperature change of plastic mulch on soil and plant was 4.351℃,2.92 percent higher than plastic mulch on soil.2 The effects of mulch treatments on rape (1) Treatments of plastic mulch on soil had the largest stomata dense, then the treatments of plastic mulch on plant. Mulching at EGS increased the stomata dense, mulching at LGS had no effects on stomata dense of plastic mulch on soil and plastic mulch on soil and plant, but increased of plastic mulch on plant.(2) The 3 mulching methods had different effects on rape growth, in which the plastic mulch on soil and plastic mulch on soil and plant could encourage plant growth; mulching for WGP could mostly increase the plant growth, mulching at LGS showed poorer effect on plant growth than mulching at EGS. As for yield characters, treatments of plastic mulching on soil was better than treatments of plastic mulching on soil and plant, treatments of plastic mulch on plant was the worst. The effects of mulching on rape quality mainly showed on the contents of glucosinolates, oil, oleic acid, and effects on other qualities were not so conspicuous. Mulching at EGS showed a increase in the contents of seed-gluco and glucosinolates, mulching for WGP could improve the oil content and oleic acid content, there were no significant difference between the mulching methods.3 The effects of mulch treatments on early rice(1) The difference of rice SPAD between mulching methods were not significant, each reach the highest content at the heading time, then decreased. The SPAD of Mulching at EGS and WGP of plastic mulch on soil were higher than mulching at LGS; but SPAD of mulching at EGS and WGP showed the contrary results.(2) Within the same mulching stage, treatments of plastic mulch on soil had the maximum stomatal density, then treatments of plastic mulch on soil and plant, and the last was treatments of plastic mulch on plant; which within the same mulching method, mulching for WGP had the maximum stomatal density, then at EGS, and at LGS the last. Mulching at WGP of plastic mulch on soil had the maximum stomatal density, the stomatal density of upper epidermis was 37.1% larger than that of mulching at LGS of plastic mulch on plant, while lower epidermis 41.39% larger than the later.(3) As for big vascular bundles area, within different methods big vascular bundles area of treatments of plastic mulch on soil was larger than that of plastic mulch on soil and plant, the treatments of plastic mulch on plant came to last. For the third upper stalks, mulching at WGP of plastic mulch on soil had the largest big vascular bundles area with 0.5432 mm which was 43.4% larger than the minimum one mulching at LGS of plastic mulch on plant of 0.3788 mm2. For the second upper stalks, mulching at WGP of plastic mulch on soil had the largest big vascular bundles area with 0.4261mm2 which was 54.83% larger than the minimum one mulching at LGS of plastic mulch on plant of 0.2752 mm2. For the uppermost stalks, mulching at WGP of plastic mulch on soil and plant had the largest big vascular bundles area with 0.2360 mm2 which was 16.37% larger than the minimum one mulching at LGS of plastic mulch on plant of 0.2028mm2. As for small vascular bundles number, the fist came to the second upper stalks, then the third upper stalks, the last was the uppermost stalk, the small vascular bundles area decline with the rise of the stalks, and within the same mulching method, it declined in the order of mulching at WGP, EGS, LGS.