The quadratic regression rotation combination design was used to investigate effects of applying nitrogen amount,ratio of nitrogen as base manure and density of spot seeding on effective spikes and single stem weight of rice population at heading stage.

Effects of seeding density on quantitative characters of oat;

Effects of Sowing Density and Seedling Age on Yield Formation and the Number of Groups in Hybrid Medium Indica Rice " Xin Liangyou 6 ";

Test on sowing density of seedy lotus in swamp soil zone of Honghu lake;

The application amount of nirtrogen, the propotion of the nitrogen in base fertilizer and the sowing density of rice dry planting were studied by rotational design of the quadratic regression with three experimental factors.

Effect of different planting density on the main agronomic traits of film-mulched wheat;

Influence of planting density on the growth of Allium mongolicum;

Effects of different planting density on the growth and fertility of thermo-sensitive male-sterile line in flax

The relation among straw flax yield,density,amount of nitrogen, NP K ratio was studied.

The relation among product of flax and different, density amount of nitrogen, NPK ratio was studied.