Effect of nitrogen foliar application in different growth stage on canopy light receiving on 3 polygerm sugar beet yield

An experiment was conducted on three sugar beet cultivars(IC, PP22 and 7233) and different application method of Nitrogen in a RCBD base factorial in three replication in 2005. Results showed that there was significant difference between light receiving in bottom and head of canopy among cultivars. N affected this attribute also. In IC the highest light receiving to bottom and head of canopy and yield in foliar N application at 6-8 leaf stage were 627 PPF, 1198PPF respectively. In soil application and 14-16 leaf stage foliar application of N led to 248 PPF in bottom and 988 PPF in head of canopy, recpectively.In IC the least root yield obtained in foliar application at 14-16 stage as 75/2 ton/ha. In PP22 light receiving to bottom and head of canopy was 472 PPF, 1134 PPF for soil and foliar application at 14-16 leaf stage and yield at that stage was 100 ton/ha. There was a %58 and %21 decreasing in light receiving to bottom and head in 6-8 leaf stage in compare with 14-16 leaf stage, foliar application at 14-16 leaf stage led to root yield increasing as %38 and %42 than soil and 6-8 leaf stage application, respectively. In 7233 cultivar highest light received to bottom was 491 PPF in 14-16 leaf stage which was %17 higher than soil application. The highest light received to head of canopy was 1190 PPF in 6-8 leaf stage foliar application. There wasn’t difference between root yield in different method N application in this cultivar. In spite of N fertilizer application led to increase leaf area and light absorption by plant canopy, there is limited information on the higher rates of N application between cultivars