Effect of Irrigation Methods on Canopy Temperature,Photosynthesis and Agronomic Traits of Autumn Sweet Corn

Effects of drip,sprinkler,and flooding irrigation methods on the temperature,humidity,and sunlight exposure on the fields of autumn sweet corn were studied in southern Fujian.The results showed:(1)At booting and flowering stages of the plants,the peak temperatures in the field with the drip and the sprinkler irrigation were2.4oC and 2.5o C,respectively,lower than the flooding method.The slight differentiations did not alter the photosynthesis and biosynthesis of the sweet corn.The peak RHs with the drip and the sprinkler irrigation were 0.5and 2.4percentage points,respectively,higher than the flooding method,while the average daily RHs were 1.9and2.6percentage points,respectively,higher than the flooding method.The greater RH provided by the two former methods supplied extra moisture and offered drought prevention for the plants.The peak sunlight exposure with the drip and the sprinkler irrigation were 2.9and 1.8percentage points,respectively,while the average daily sunlight exposure was 2.6and 1.8percentage points,respectively,more than the flooding method.Thus,the drip and the sprinkler irrigation increased the sunlight utilization of the plants.(2)In the entire growing stage of the plants,the average surrounding air temperatures with the drip,sprinkler,and flooding irrigation were 24.1℃,23.8℃,and24.4℃,respectively.The temperature range resulted from the drip and the sprinkler irrigation was more conducive to the pollination grouting and dry matter assimilation of the sweet corns.The average RHs with the drip,sprinkler,and flooding irrigation were 48.3%,49.4%,and 46.4%,respectively.The higher RH induced by the drip or sprinkler irrigation benefited the development,water metabolism,and growth of the corn plants.The average sunlight exposure rates with the drip,sprinkler,and flooding irrigation were 39.6%,40.2%,and 36.2%,respectively.Hence,the two former methods of irrigation provided a greater photosynthesis for the plants.And,(3)The yield of the sweet corns grown under the drip or sprinkler irrigation was significantly higher than that of the flooding method.There were significant effects observed of the drip irrigation on the plant height,ear length,ear weight,and root weight of the plants,and those of the sprinkler irrigation on the spike rate,bald tip length,and green leaf count of the sweet corn.