Abstract: In order to reveal the difference rules of photosynthetic traits between orthogonal and reciprocal combinations of Brassica napus and provide theoretical basis for high photosynthetic efficiency breeding of rapeseed,19 pairs of orthogonal and reciprocal combinations which had the different genotype and their parents were chosen as test materials to compare the net photosynthetic rate,chlorophyll content,heterosis and parent-offspring correlation.Results showed that:The net photosynthetic rate and chlorophyll content of orthogonal combinations were higher than that of reciprocal combinations with same genotype by -8.93%-25.33% and -7.37%-8.70% respectively and the average value was 2.34 and 1.26 percent,respectively.There were 10,11 orthogonal combinations of which were higher than reciprocal combinations;The over-stand heterosis,mid-parents heterosis and over-parent heterosis of net photosynthetic rate of 10 orthogonal combinations and chlorophyll content of 11 orthogonal combinations were higher than corresponding reciprocal combinations;The net photosynthetic rate and chlorophyll content of orthogonal and reciprocal combination hybrids F₁ all had significant or extremely significant positive correlation with their female parent,male parent,mid-parent value,high parent value and low parent value and the correlation with high parent was higher than that of low parent.The correlation of net photosynthetic rate,chlorophyll content between F₁ and their female parent were higher than that of male parent in orthogonal combinations and the result was opposite in reciprocal combinations;The direct active affection that female parent had on net photosynthetic rate and chlorophyll content of orthogonal combination hybrids F₁ which were 0.622 and 0.579 respectively were higher than that of orthogonal combination hybrids F₁ which were 0.463 and 0.325 respectively.The values of net photosynthetic rate and chlorophyll content,mean of heterosis and appearance probability of strong superiority crosses in orthogonal combinations were higher than that in reciprocal combinations.

Key words: Basic napus, Orthogonal and reciprocal combinations, Net photosynthetic rate, Chlorophyll content, Heterosis, Comparison

CLC Number: 

• S635.01