Effect of water soluble alginic acid fertilizer on the growth, yield and quality of pear

Abstract:【Objective】Effects of water soluble alginic acid fertilizer on the growth and fruit quality of pear were investigated in order to reduce the use of chemical fertilizers.【Methods】‘Whangkeumbae’and‘Suli’pears were used as the materials for the experiment, which was performed in the villages of Liuhudong, Erqi district, Zhengzhou and in the villages of Yuzhuangzhai, Ningling county, Shangqiu.There were five treatments in the experiment, including the conventional fertilization treatment[NPK (C) ], traditional water soluble fertilizer treatment[NPK (F) ]with equivalent NPK, alginic acid water solution treatment with equivalent NPK[NPK (HF) ], alginic acid solution with 25%reduction in NPK, and alginic acid solution with 50%reduction in NPK.All the treatments were with three randomly arranged replicates.In[NPK (C) ]treatment, the total annual doses of N, P and K were 270 kg·hm-2, 120kg·hm-2and 270 kg·hm-2respectively in‘Whangkeumbae’orchard, and 337.5 kg·hm-2, 150 kg·hm-2and 337.5 kg·hm-2respectively in‘Suli’orchard.In all the treatments, the fertilizers were applied during sprouting stage (March 20;March 25) , the first fruit expanding stage (May 20;May 25) , and the second fruit expanding stage (July 20;July 25) , with 40%, 35%and 20%of total fertilizer application respectively in both‘Whangkeumbae’and‘Suli’pear orchards.【Results】The treatment of 3/4NPK (HF) had a leaf area 19.55%and 11.65%larger, a sugar acid ratio 27.87%and 7.67%higher, a N nutrition content in 19.56%and 6.08%greater, and stone cells 42.85%and 42.85%less than NPK (C) and NPK (F) treatments, respectively in‘Whangkeumbae’orchards.The fruit weight under 3/4NPK (HF) and 12NPK (HF) treatments was decreased significantly by 23.41%and 17.14%, respectively, compared with NPK (HF) treatment.However, there were no significant differences in the growth and quality (excep for mean fruit weight) among alginic acid treatments.In addition, the treatment of 3/4NPK (HF) had no significant effect on the N, P and K nutrient uptake in fruit and leaves, but the N content in the leaves in1/2NPK (HF) treatment was significantly decreased by 17.27%compared with NPK (HF) treatment.In‘Suli’pear orchard, the shoot length, hundred leaf fresh weight, soluble sugar and TSS contents under NPK (HF) treatment were 12.47%, 12.99%, 5.20%and 8.72%higher respectively compared with NPK (C) treatment.However, there was no significant difference in fruit nutrient contents between NPK (C) and NPK (HF) treatments.Moreover, the reductions in dose of alginic acid fertilizers had no significan effect on pear growth and yield (except for the shoot) .Interestingly, leaf N nutrient content was significantly increased by 3/4NPK (HF) and 1/2NPK (HF) treatments, while soluble sugar and N contents in the fruit were decreased, especially for 1/2NPK (HF) treatment.Furthermore, correlation analysis showed that the quantity of alginic acid application was significantly negatively correlated with PEP but significantly positively correlated with shoot length, fruit soluble sugar, TSS and N nutrient contents, indicating that the quality and N nutrient uptake of‘Suli’pear depended on the doses of fertilizer applied.Fertigation management increased the economic profits in pear orchard under the same fertilizer dosage.In comparison with NPK (HF) treatment, the economic profits under 3/4NPK (HF) and 12NPK (HF) treatments increased by 735 Yuan·hm-2and 4 135.2 Yuan·hm-2respectively for‘Whangkeumbae’orchard, and 398 Yuan/hm2and 3 936.1 Yuan·hm-2respectively for‘Suli’pear orchards【Conclusion】The water soluble alginic acid fertilizer increased growth and quality of pears, and reduced manpower.Additionally, there was no significant decrease in the fruit quality and yield if the dosage of alginic acid was reduced.Among all the treatments examined, the optimal fertilizer treatmen was 3/4NPK (HF) .