| Usually, nitrogen is the main limiting factor in garlic production. At present, it is one-sided pursuit of high-yield, farmers using nitrogenous fertilizer blindly and excessively duringthe planting of garlic. With the increasing in the amount of nitrogen fertilizer, the yield ofgarlic increased to a certain extent, but also this has resulted in many problems, such asdecreasing the quality of garlic, economic decline and environmental pollution. So how toimprove nitrogen utilization of the garlic is a key problem that should be solved.In recent years, because of greenhouse and plastic greenhouse universal access, manyyears of succession cropping and multiple cropping index increased, it causes excessive boronconsumption and the phenomenon of boron deficiency has become increasingly commonproblem. The balance of the boron application and boron demand for plant growth is growingconcern. At the same time, nitrogen and boron fertilizer have a close relationship with theformation of onion-type garlic. Effects of different N and B nutrition on garlic growth werestudied by nutrient solution.‘Cangshansuan’（Allium sativum.L） was tested in this research bymeans of nutrient solution （DFT） experiments.1. Effect of nitrogen on physiological, quality of garlic and the formation of onion-typegarlicEffects of different nitrogen levels on physiological characteristics, quality of garlic andthe formation of onion-type garlic were studied by using nutrient solution(the nitrogen contentin Hoagland nutrient was15mmol·L-1). Four different nitrogen concentrations at0,7.5,15and22.5mmol·L-1were designed. The main results were as follows:1). The proper concentration of nitrogen in nutrient solution could promote garlic growth.The garlic increments, photosynthetic parameters （Pn, Tr, Gs） and the activity of protectionenzyme （POD, CAT, SOD） in leaf reach their maxima when the nitrogen content is7.5mmol·L-1. When the boron concentration is15mmol·L-1, these indexes are decreased. And onthis concentration, photosynthetic pigment contents and the activity NR were higher than theother treatments.2). The contents of soluble sugar, soluble protein, vitamin C （Vc） and allicin in garlicfirst increased and then decreased with the increase of nitrogen concentration，its reachedmaximum while boron content was7.5mmol·L-1. Meanwhile，these indexes in bolt of garlic were34.29%，41.27%，20.23%and22.86%higher than the treatment of0mmol·L-1N;while these indexes increased by34.60%，65.89%,9.62%and522.06%, in bulb.3). The contents of N, K and Mg in bulb were first increased and then decreased with theincrease of nitrogen concentration. The absorption of K and Mg was higher whenconcentration of nitrogen was7.5mmol·L-1, the highest N content was obtained by15mmol·L-1nitrogen treatment. The P and Ca concentration in bulb decreased as nitrogenconcentration increased.4). The onion-type garlic can be induced when boron content were7.5,15or22.5mmol·L-1, as well as fresh and dry weight of bulb decreased at these concentrations. Theoccurring rate of onion-type garlic increased as nitrogen concentration increased. Comparedwith normal plants, growing of the onion-type garlic was premature stop. During the earlygrowing stage of bulb, the photosynthetic pigment contents, photosynthetic rate and theactivity of protection enzyme （POD, CAT, SOD） in leaf were lower than the normal plantswhich in the same condition as the onion-type garlic. Under the7.5mmol·L-1, the contents ofsoluble sugar, soluble protein and free amino acids were195.97%,276.13%and121.41%lower than the normal plants. These indexes decreased by120.57%,209.97%and112.11%asnitrogen concentration was15mmol·L-1, and decreased by35.69%,171.11%and81.93%when N concentration was22.5mmol·L-1.2. Effect of boron on physiological, quality of garlic and the formation of onion-typegarlicEffects of different boron levels on physiological characteristics, quality of garlic and theformation of onion-type garlic were studied by using nutrient solution. Four different nitrogenconcentrations at0,0.5,1.0and1.5mg·L-1were designed. The main results were as follows:1). The boron contents of garlic are increased with the boron concentrations rangingfrom0to1.5mg·L-1, which reaches the maximum when the boron concentration in nutrientsolution is1.5mg·L-1. At the same time, the garlic increments，photosynthetic pigmentcontents，photosynthetic parameters （Pn，Tr and Gs） in leaf laminas are increased with theincrease of boron levels in the range of0–1.0mg·L-1, and those reach their maxima when theboron content is1.0mg·L-1. When the boron concentration is1.5mg·L-1, these indexes aredecreased.2). The highest concentrations of Vc, soluble protein, allicin in leaf laminas andpseudostems of garlic seedling were obtained by1.0mg·L-1boron treatment. Meanwhile, thecontents of soluble sugar and free amino acids in leaf laminas are reduced by34.3%and 22.8%, while the contents of soluble sugar and free amino acids in pseudostems are improvedby160.5%and43.6%. And on this concentration, the content of soluble sugar, soluble protein,Vitamin C （Vc）, free amino acids and allicin in bolt and bulb were71.33%and59.20%,47.91%and131.79%,50.02%and68.71%,62.80%and38.83%,57.69%and50.94%higherthan the treatment of0mg·L-1boron concentration.3). The1.0mg·L-1boron concentration in nutrient solution could promote the absorptionand accumulation of N, P, K and Mg in bulb of garlic. The Ca concentration in bulb decreasedas nitrogen concentration increased.4). The onion-type garlic can be induced when boron content were0mg·L-1or1.5mg·L-1,as well as fresh and dry weight of bulb decreased at these concentrations. Compared withnormal plants, the onion-type garlic senescence was slower. During the late growing stage ofbulb, the boron content, photosynthetic pigment contents，photosynthetic parameter（Pn, Trand Gs） and the activity of protection enzyme （POD, CAT, SOD） in leaf were higher than thenormal plants which in the same condition as the onion-type garlic. It can be respectivelyincreased the content of soluble sugar, soluble protein and free amino acids which include inleaf laminas and pseudostems of onion-type garlic, when the boron in nutrient solution were0mg·L-1and1.5mg·L-1. And on these concentrations, the content of soluble sugar, solubleprotein and free amino acids in bulb reduced by30.45%and51.99%,152.26%and258.34%,82.01%and56.09%. |
