Effects Of Different Cultivation Patterns On Photosynthesis,Yields And Its Components Of Shanlan Upland Rice

Shanlan upland rice(Oraza Saliva L.)is a kind of dryland rice in Hainan mountainous area.In the past,slash-and-burn cultivation pattern known as damaging the environment was mainly used in these planting areas,and the Shanlan upland rice was showed up in poor agronomic traits and low yield.Although paddy cultivation could optimize the agronomic traits and increase the yield of Shanlan upland rice,the large water consumption of submerged irrigation was not conducive to the development of water-saving agriculture.In order to achieve the goal of both high yield and water saving in Shanlan upland rice production,the water-saving irrigation method for Shanlan upland rice under dry farming sprinkler irrigation was proposed and compared with the traditional upland and paddy cultivation methods.The photosynthesis,agronomic traits.material accumulation and transportation,yield and its components,physiological indexes and changes in the anatomical structure of roots and stems of Shanlan upland rice were studied,aiming to obtain high-yield cultivation pattern for water-saving irrigation of Shanlan upland rice,and analyzes its high-yield mechanism.In addition,we also studied the effects of plastic film mulching on photosynthetic characteristics,yield,plastic film degradation speed and weed control of Shanlan upland rice under flooding,moistening,sprinkler irrigation and drought conditions.The main results are as follows:1.The whole growing period of dry farming sprinkler irrigation was shorter than that of traditional dry farming,but higher than that of water farming.The agronomic traits of Shanlan upland rice were optimized by dry farming sprinkler irrigation,resulting in higher SPAD value of functional leaves,higher stomatal conductance and transpiration rate of flag leaves,and higher net photosynthetic rate at heading and full heading stages.Flooding irrigation significantly increased the yield of Shanlan upland rice,but decreased its water use efficiency.Dry farming sprinkler irrigation had the greatest increase in yield.Although the seed setting rate and 1000-grains weight of dry farming sprinkler irrigation were inferior to those of water irrigation because of its weaker grain filling ability of superior and inferior grains,the effective panicles and the number of grains per panicle were significantly higher than those of water irrigation,and its yield was significantly increased.Compared with traditional dry farming,Shanlan upland rice under dry farming sprinkler irrigation showed the root radius increased,the cortex thickens,the large vessel and middle columns becomes larger,the tillering ability of the plants enhances,and the dry quality and the rate of substance output and conversion of the stem and sheath at the heading and maturity stages increased,and the number of spikes and grains per panicle increased.In addition,dry farming sprinkler irrigation enlarged the large vascular bundles in Shanlan upland rice stems and increased the water and nutrient transport capacity of large vascular bundles.We can conclude that dry farming sprinkler irrigation was the best cultivation method of Shanlan upland rice.2.Film mulching cultivation shortened the growing period and increased yield of Shanlan upland rice.Although the seed setting rate and 1000-grains weight of sprinkler irrigation mulched with plastic film were lower than those of flooding farming mulched with film,the effective panicles per hole and the number of grains per panicle were significantly increased,and its yield was significantly higher than the other three film mulching methods and bare dry farming.In addition,film mulching significantly increased stomatal conductance and transpiration rate of flag leaf,SPAD value of functional leaves and net photosynthetic rate of flag leaf of Shanlan upland rice at heading stage.The net photosynthetic rate of flag leaf under film mulching paddy irrigation was significantly higher than that under dry farming film mulching and bare dry farming,but there was no significant difference among three different irrigation film mulching patterns.3.Film mulching inhibited the growth of weeds in the field.The weed control effect of film mulching paddy cultivation for 20 days is higher than that of film mulching upland cultivation.The weed control effect of moistening Mulching for 45 days decreased,which was mainly because that the biodegradable film easily degraded in moistening water cultivation.After jointing stage,amounts of plastic film ruptured,which reduced the weed control efect.4.Under paddy farming condition,plastic film entered the degrading induction period and breaking-up period earlier than sprinkler irrigation and drought conditions,a small number of cracks appeared at the beginning of tillering stage and a large number of cracks occured at the peak tillering stage.Under flooding and wet conditions,plastic film almost completely degraded at the heading stage,while under sprinkler irrigation and drought conditions,plastic film did not completely degrade after the maturity stage.But the plastic film under sprinkler irrigation entered the induction and bursting period in advancecompared with the drought condition.