Effects Of Phosphorus In Nutrient Solution On Physiological Characteristics,Yield And Quality Of Garlic

Effects of different phosphorus concentrations on physiological characteristics, yield and quality of garlic were studied under hydroponic culture, in order to provide the reference for the rational use of phosphate fertilizer of garlic."Jinxiang3" were tested in this research, with Hoagland and Arnon nutrient solution based, five phosphorus applications levels of0mmol·L1、0.5mmol·L-1、1.0mmol·L-1、1.5mmol·L-1、2.0mmol·L-1和2.5mmol·L-1was treated to study the effect of phosphorus on growth and development, nutrient absorption, photosynthetic characteristics, active oxygen metabolism, yield and quality of garlic.,The main conclusions are as follows:1. The plant fresh weight, plant height, leaf width, leaf area, pseudostem length and pseudostem diameter of garlic seedling were increased at first and then decreased with the increase of phosphorus concentrations, and these indexes reached the maximum at1.5mmol·L-1phosphorus concentration.2. With the increase of phosphorus levels, the elements contents of P, K, Ca and Mg in garlic seedling leaf increased, but when phosphorus concentrations was extremely low or high, the contents of P, Ca and Mg would be lack or excessively accumulative, in addition to potassium elements. At the same time, there was a parabola relationship between the contents of N and Zn in garlic seedling leaf and phosphorus levels, and the elements absorption of N and Zn was inhibited when the phosphorus level was extremely low or high. The contents of P and K in bolt and bulb increased with the increase of phosphorus levels, while N content was parabola relationship.3. Application of phosphate fertilizer could significantly enhance the photosynthetic performance of garlic seedling leaf. The photosynthetic pigment contents and photosynthetic parameters (Pn, Tr, Gs) of leaf were the highest at1.5mmol·L-1phosphorus concentration, and they were decreased at below or above1.5mmol·L-1.4. After sowing on80and160days, the MDA content in garlic seedling leaf were decreased at first and then increased with the increase of phosphorus concentrations, and reached the minimum at1.5mmol·L-1phosphorus concentration, which were decreased by30.92%and42.35%compared to the treatment of0mmol·L-1. At the same phosphorus treatment, protective enzymes (SOD、POD and CAT) activities in garlic seedling leaf on80 days were lower than on160days after sowing. The protective enzyme activity were decreased at first and then increased with the increase of phosphorus concentrations on80days after sowing, while were increased at first and then decreased on160days after sowing. At this stage, the protective enzyme activity of phosphorus deficiency or high phosphorus treatment decreased sharply, and the protective enzyme activity of middle phosphorus treatment remained at a relatively high level. Collectively, active oxygen metabolism system in garlic seedling leaf was at the treatment of1.5mmol·L-1to maintain the best state. It shows that the response of protective enzymes activities to phosphorus levels supplied, should not be studied by static state or absolute activity of protective enzyme, but should consider the cumulative effects of different phosphorus treatments.5. Phosphorus deficiency seriously affects the yield formation of bolt and bulb. The fresh weight of bolt, the bolt diameter, the fresh weight of bulb and the transverse diameter of bulb, were increased with the increase of phosphorus concentrations in the range of0～1.5mmol·L-1,and then they were decreased. These yield indexes at the treatment of1.5mmol·L-1were the highest, which were increased by305.79%、396.20%、868.63%and182.97%compared to the treatment of0mmol·L-1. Thus it can be seen that, application of phosphate fertilizer could significantly promote the formation of bolt’s and bulb’s yield, and the biggest promotion was at the treatment of1.5mmol·L-1.6. Phosphate fertilizer has a significant impact on the formation of the nutrition quality of garlic. The contents of allicin, soluble sugar, free amino acid and soluble protein in garlic seedling leaf and pseudostem, as well as vitamin C content in leaf, reached the highest at1.5mmol·L-1phosphorus concentration. Too low or too high phosphorus supplied were not conducive to the increase of nutrition quality index. The contents of vitamin C, soluble sugar, free amino acid and soluble protein in bolt and bulb reached the maximum at the1.5mmol·L-1phosphorus concentration, while allicin content at2.0mmol·L-1.