however, appropriate water and fertilizer coupling mode can increase stomatal conductance, reduce co2 compensation point in leaves and strengthen co2 assimilation capacity in mesophyll cells,greatly increasing photosynthetic activity, thereby increasing photosynthetic rate Zhai etal found that a reasonable increase in application amount of nitrogen fertilizer can increase the relative chlorophyll content in leaves and increase the actively of rice roots,therefore benefiting the growth and development of rice.