| Oyza sativa L.is one of the important food crops,China's production and consumption of rice has always been at the forefront of the world.With the rising global temperature in recent years,the water shortage and frequent drought has severely restricted rice production.As another ecological type of cultivated rice,upland rice mainly grew on dryland,which has the advantage of being more water-saving and drought-tolerant compared with irrigated rice.However,the phenotypic differences between irrigated rice and upland rice in adaptability to dryland are still unclear.This study including 75 irrigated rice and 90 upland rice germplasm resources from major rice producing areas was used as representative test materials.In the field trial of the Agricultural College of Yunnan University in Xishuangbanna,Yunnan Province,three seasons(2017 early rice,2017 late rice,2018 early rice),two ecological environments(paddy,dry land)was used for the two types of ecological rice(irrigated rice,upland rice)testing.And three replicates were used for to evaluate their phenotypic traits such as yield,yield related traits,photosynthetic traits and water use efficiency.The results are as follows:1.The yield of irrigated rice in paddy field and dryland was 27.49 g and 10.36 g per plant respectively,while the yield of upland rice in paddy field and dryland was 22.78 g and 10.59 g per plant respectively.The result indicated that irrigated rice and upland rice could produce a certain yield in both paddy and dryland environments,and the yield of both in paddy field were higher than that in dryland environment(P<0.001).Further analysis showed that the yield of irrigated rice in dryland was 62.31%lower than that in paddy field,while yield of upland rice in dryland environment was 53.51%lower than that in paddy field.Compared with paddy field,the yield decrease of upland rice in dryland was significantly lower than that of irrigated rice,which indicated that upland rice is more suitable for growth in dryland than irrigate rice,while irrigate rice is more suitable for growth in paddy field,and upland rice has remarkable dryland adaptability.2.The seed setting rate of irrigated rice in paddy field was 78.66%,the seed setting rate in dryland environment was 64.52%,and the seed setting rate of upland rice in paddy field and dryland was 81.37%and 71.92%respectively,showed that seed setting rate of irrigated rice and upland rice in paddy field and the dryland all exceeded 50%,and rice cultivation has wide adaptability.Further analysis showed that there was no significant difference in the seed setting rate between irrigated rice and upland rice in paddy field(P=0.095).The seed setting rate of upland rice in dryland was significantly higher than that in irrigated rice(P<0.001),indicated that upland rice has more obvious advantage compared with irrigated rice,that means upland rice has higher seed setting rate,which also indicated that the upland rice has the potential to obtain higher yield and has dry land adaptability.3.Further analysis of yield showed that the harvest index of irrigated rice in the paddy field was 53.70%,which was significantly higher than that of the upland rice,which was 48.83%(P<0.001).In the dryland environment,the harvest index of irrigated rice was 39.75%,the harvest index of upland rice was 42.73%.The harvest index of upland rice is significantly larger than that of irrigated rice(P=0.001).indicated that upland rice can obtain more economic benefits than irrigated rice in the case of accumulating the same biomass on dry land.Compared with upland rice,irrigated rice is more incompatible with the dryland environment and more adaptable to paddy field.Conversely,upland rice is more adaptable to dryland.4.Effective panicle of irrigated rice in paddy filed was 11 panicles per plant,effective panicle in dryland was 6 panicles per plant,for upland rice,effective panicle in paddy field and dryland was 9 and 5 panicles per plant.respectively.Which showed that the effective panicles of irrigated rice and upland rice in paddy field are larger than that in dryland.5.The plant height of the irrigated rice was 99.18cm in paddy field and 84.77cm in dryland,the plant height of the upland rice was 122.01cm in paddy field and 108.98cm in dryland,which indicated that the plant height of irrigated rice and upland rice in paddy field is higher than that in dryland,but the dryland environment has less impact on the plant height of upland rice than the lrrigated rice.Compared with irrigated rice,the upland rice can accumulate more biomass,and is more adapt to the dryland environment.6.The thousand-grain weight of irrigated rice in the paddy field environment was 23.75 g/plant,which was significantly higher than that of the dryland of 22.33 g/plant,the thousand-grain weight of the upland rice in the paddy field was 25.74 g/plant and there is no significant difference between the that under dryland of 25.13 g/plant.It indicated that irrigated rice is more suitable for paddy field environment,and upland rice is more suitable for dryland environment.Further analysis showed that the thousand-grain weight reduction in irrigated rice was 5.98%,and the reduction of upland rice was 2.37%.It also showed that irrigated rice is more suitable for paddy field,and upland rice is more suitable for dryland.7.Net photosynthetic rate is an important factor in determining rice yield.The net photosynthetic rate(19.31?mol·m2·s-1)of irrigated rice in paddy field was higher than that in dryland(12.70?mol·m2·s-1)and the phenotypic value was significantly different(P<0.001),indicated that irrigated rice can accumulate more dry matter under paddy environment,which can explain the phenonmenon that the yield of rice under paddy environment is higher than that under dryland environment.In the paddy field,the net photosynthetic rate(18.56?ol· m2·s-1)of upland rice was smaller than the net photosynthetic rate of irrigated rice(19.31?mol·m2·s-1)and the difference was significant(P<0.001);in dryland environment the net photosynthetic rate of upland rice was 14.89(?mol·m2·s-1,and the net photosynthetic rate of irrigated rice was 12.70?mol·m2·s-1.The net photosynthetic rate of upland rice was high and the difference was significant(P value less than 0.001).The variation trend of the yield of irrigated and upland rice in water and dryland was consistent with the change trend of net photosynthetic rate,indicated that the net photosynthetic rate had a greater impact on yield,and also showed that the effect of dryland water shortage on net photosynthetic rate of irrigated rice was more obvious than that of upland rice.Upland rice is more adapted to the dryland environment than irrigated rice.8.The transpiration rate of irrigated rice in paddy field was 6.82mmol·m2·s-1,while that in dryland environment was 4.60mmol ·m2· s-1;and the transpiration rate of upland rice in paddy field and dryland was 6.15mmol·m2·s-1 and 4.60mmol·m2·s-1,respectively.Which indicated that the transpiration rate of upland rice in dryland environment is less than the paddy field environment,transpiration rate of both upland and irrigated rice can be adjusted according to changes in the ecological environment.Further analysis showed that the transpiration rate of irrigated rice was reduced by 32.55%,and the reduction of upland rice was 25.20%,indicated that irrigated rice has adaptability to paddy field environment,while upland rice has adaptability to dryland environment.9.The water use efficiency of irrigated rice in paddy field was 3.05,that in dryland was 3.46;the water use efficiency of upland rice in paddy field is 3.30,and that in dryland was 3.71,indicated that the water use efficiency of irrigated rice and upland rice in dryland environment is higher than that of paddy field,which is related to the lack of water in dryland environment,and it is also a regulation mechanism of rice on water shortage environment.Furtherly,we found that the water use efficiency of upland rice in paddy field environment and dry land environment was greater than that of irrigated rice,indicated that more effective water use mechanism has been formed in the process of long-term adaptation of upland rice to dryland environment.In summary,compared with irrigated rice,the seed setting rate,plant height,1000-grain weight,water use efficiency,net photosynthetic rate and harvest index traits of upland rice is more suitable to dryland environment;compared with upland rice,the effective panicle,net photosynthetic rate and harvest index traits of irrigated rice is more suitable for the paddy field environment,which is the result of long-term adaptation of their adapted environments.The research results have certain theoretical and practical significance for improving the dryland adaptability of rice by using upland rice resources. |
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