Effect of Nitrogen Topdressing on Growth and Yield of Garlic

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1. Kingenta Ecological Engineering Group Co., Ltd., Linshu 276700, China; 2. Key Laboratory of Plant Nutrition and New Fertilizer R&D, Ministry of Agriculture, Linshu 276700, China

1 Introduction

The period of garlic seedling establishment is the transition period from non-growth state of garlic under winter low temperature to gradual thriving. The garlic seedling growth rate and quality at this stage have a direct impact on the later growth and yield of garlic stems and garlic bulbs. At the early stage of garlic growth, the main source of nutrients is from garlic shoot and some soil nutrients. Garlic’s demand for nutrients is mainly in the period of seedling establishment or after. The supply of nutrients, especially nitrogen in the period of seedling establishment, has an important impact on the late garlic growth. Different forms of nitrogen have different effects on crop growth. A number of scholars use water culture method to study the effect of different forms of nitrogen on the roots of rice, wheat, corn, soybeans and other crops at the seedling growth stage[1-3], and the results show that ammonium nitrogen and nitrate nitrogen have significantly different effects on roots, that is, ammonium nitrogen makes the roots become significantly short and thick, while nitrate nitrogen increases the root length and lateral roots[4]. Obviously, the form of nitrogen can change the form of crop root, and affect the crop absorption. By studying the effect of nitrogen on crop growth, we can determine the best form of nitrogen suitable for crop growth and the optimum nitrogen fertilizer ratio to improve yield and quality. In this study, with two different varieties of garlic as experimental materials, by applying different forms of nitrogen fertilizer, we systematically explore the response of garlic to different forms nitrogen fertilizer, with a view to provide the experimental basis for nitrogen topdressing on garlic.

2 Materials and methods

2.1OverviewoftheexperimentalsiteThe experiment was carried out in Youzhuang Village, Luzuo Town, Cangshan County, from September 2014 to May 2015. The soil is Shajiang black soil, with high and even fertility, and there are good irrigation conditions. pH value of 0-20 cm soil is 6.5; average organic matter content is 16.8 g/kg-1; total nitrogen content is 1.29 g/kg-1; alkali-hydrolyzable nitrogen content is 98.34 mg/kg-1; available phosphorus content is 27.4 mg/kg-1; available potassium content is 116.11 mg/kg-1.

2.2ExperimentaldesignThe experiment selects two cultivars with different production purposes: the first one is early bolting garlic, with early sprouting and high yield of garlic stems, and the garlic sprouts produced are mainly supplied for early spring markets; the second one is Cangshan garlic, with high yield of garlic stems and garlic bulbs. The early bolting garlic was sown on September 29, 2014, with seeding rate of 675000 plants per ha; Cangshan garlic was sown on October 3, 2014, with seeding rate of 600000 plants per ha. The same amount of same base fertilizer was applied before sowing, namely 15-15-15 1500 kg/ha-1potassium sulfate compound fertilizer, and 1200 kg/ha-1FA-K organic fertilizer. Other cultivation and management measures are also consistent. During the first time watering (around April 5), three different nitrogen topdressing treatments were set for each variety of garlic, namely T1urea (300 kg/ha-1, N=138 kg/ha-1); T2ammonium chloride (575 kg/ha-1, N=9.2 kg/ha-1); T3ammonium phosphate (431.25 kg/ha-1, N=9.2 kg/ha-1). 330 m2of plot was set for each treatment, and replicate was no longer set. On April 15, plant height and stem diameter were determined; on April 30, garlic stems of early bolting garlic were harvested; on May 6, garlic stems of Cangshan garlic were harvested; on May 16, garlic bulbs of early bolting garlic were harvested; on May 22, garlic bulbs of Cangshan garlic were harvested.

2.3SamplecollectionanddeterminationAfter 10 days of topdressing, the plant height and stem diameter of 20 garlic plants were continuously determined under each treatment. The plant height was measured with a meter stick, from the ground to the highest point of plant; the stem diameter was measured with caliper, according to the thickest part above the ground. During the harvesting of garlic stems, 2.5 m×1 m plot was selected under each treatment, to measure garlic stem yield, and each treatment was repeated three times; during the harvesting of garlic bulbs, 60 garlic plants were continuously chosen under each treatment, to measure garlic bulb yield, and each treatment was repeated three times.

2.4DataprocessingMicrosoft Excel 2010 is used to analyze experimental data and draw diagram, and SPSS18 is used to perform significant difference test on data (Duncan SSR method, α = 0.05).

3 Results and analysis

3.1EffectofdifferentformsofnitrogenfertilizerongarlicplantheightandstemdiameterAs can be seen from Table 1, after 10 days of different nitrogen topdressing, there are differences in plant height and stem diameter between two kinds of garlic. For early bolting garlic, the garlic plant height is greatest under T3, significantly higher than under T1, an increase of 5.2%; the garlic plant height under T2is also greater than under T1, but the difference is not significant. There are no significant differences in stem diameter among the three treatments, but the stem diameter is in the order of T3>T2>T1. For Cangshan garlic, the garlic plant height under T3and T2is significantly higher than under T1, an increase of 10.8% and 6.1%, respectively; the difference is not significant between T3and T2, but the plant height is in the order of T3>T2. There are no significant differences in stem diameter among the three treatments, but the stem diameter is in the order of T3>T2>T1. This shows that under the same climatic conditions, the nitrogen supply for garlic under T3is significantly faster than under T1and T2, and the supply under T2is also faster than under T1.

Table1Effectofdifferenttreatmentsonplantheightandstemdiameterofdifferentgarlicvarieties

VarietyTreatmentPlantheightcmPlantheightincreasecomparedwithT1∥%StemdiametermmStemdiameterincreasecomparedwithT1∥%EarlyboltinggarlicT178.1±1.2b-15.2±1.4a-T280.5±1.2ab3.015.3±1.6a0.4T382.2±1.8a5.215.5±1.8a1.8CangshangarlicT165.3±0.8b-13.5±1.6a-T269.3±1.3a6.113.6±1.4a0.2T370.7±2.4a10.814.1±0.6a4.4

Note： Different letters represent differences between different treatments of the same garlic variety, the same below.

3.2EffectofdifferentformsofnitrogenfertilizeronyieldofgarlicstemsandgarlicbulbsAs can be seen from Table 2, different nitrogen topdressing has significant effect on garlic yield. As for early bolting garlic, the yield of garlic stems under T3is 10.5% significantly higher than under T1; the yield of garlic stems under T2also tends to be higher than under T1, but the difference is not significant; there is no significant difference in the yield of garlic stems among the three treatments, but it is in the order of T3>T2>T1. As for Cangshan garlic, the yield of garlic stems under T3is 9.1% significantly higher than under T1; the yield of garlic stems under T2also tends to be higher than under T1, but the difference is not significant; the yield of garlic bulbs under T2and T3is significantly higher than under T1, an increase of 5.7% and 6.5%, respectively, compared with T1.

Table2Effectofdifferenttreatmentsontheyieldofgarlicstemsandgarlicbulbsofdifferentgarlicvarieties

VarietyTreatmentYieldofgarlicstemsg/667m2YieldincreasecomparedwithT1∥%Yieldofgarlicbulbskg/667m2YieldincreasecomparedwithT1∥%EarlyboltinggarlicT113417.5±510b-14122.5±307.5a-T213891.5±565.5ab3.514442±316.5a2.3T314821.5±475.5a10.514737.5±325.5a4.4CangshangarlicT17602±276b-22737±474b-T27747.5±261ab1.924031.5±228a5.7T38293.5±186a9.124220.5±381a6.5

3.3EconomicbenefitsofapplyingdifferentformsnitrogenfertilizerAs can be seen from Table 3, in terms of early bolting garlic, both the economic benefits of garlic stems and garlic bulbs, and the economic benefits per ha, are in the order of T3>T2>T1; the economic benefits per ha under T2are 2628 yuan higher than under T1, while the economic benefits per ha under T3are 6690 yuan higher than under T1. Cangshan garlic shares the similar trend with early bolting garlic: T3>T2>T1. The economic benefits per ha under T2are 3537 yuan higher than under T1, while the economic benefits per ha under T3are 5490 yuan higher than under T1.

Table3Economicbenefitsofdifferentvarietiesofgarlicunderdifferenttreatments

VarietyTreatmentEconomicbenefitsofgarlicstemsyuan/ha-1Economicbenefitsofgarlicbulbsyuan/ha-1Economicbenefitsperhayuan/ha-1Topdressingcostsyuan/ha-1IncomeincreasecomparedwithT1∥yuan/ha-1EarlyboltinggarlicT161720.52259684316.5510T263901.523107.587009574.52628T368179.52358091759.512636690CangshangarlicT125846.554568.580415510T226341.55767584016.5574.53537T328198.558129.58665812635490

Note： For early bolting garlic, the price of garlic stems and garlic bulbs is 4.6 yuan/kg and 1.6 yuan/kg, respectively; for Cangshan garlic, the price of garlic stems and garlic bulbs is 3.4 yuan/kg and 2.4 yuan/kg, respectively; the price of urea, ammonium chloride and ammonium phosphor nitrate is 1700 yuan/t, 1000 yuan/t, and 2200 yuan/t, respectively.

4 Conclusions and discussions

With Cangshan garlic and early bolting garlic as experimental materials, this paper studies the effect of nitrogen topdressing on the garlic growth and yield of garlic stems and garlic bulbs. The results show that under the same amount of nitrogen, applying ammonium phosphor nitrate can better promote the growth of garlic than applying urea and ammonium chloride; both ammonium chloride and ammonium phosphor nitrate can effectively improve the yield of garlic stems and garlic bulbs, especially for ammonium phosphor nitrate; through economic benefit analysis, applying ammonium chloride and ammonium phosphor nitrate can produce greater economic benefits than applying urea, and especially ammonium phosphor nitrate increases the economic benefits of Cangshan garlic and early bolting garlic by 5490 yuan and 6690 yuan per ha, respectively. Thus, applying ammonium phosphor nitrate as topdressing for garlic can effectively increase yield and income. Different forms of nitrogen in the soil will be converted into each other, and then be absorbed by plants. Under suitable temperature, moisture and aeration conditions, due to the action of soil microbes and enzymes, urea is hydrolyzed into ammonium nitrogen, and ammonium nitrogen is oxidized into nitrate nitrogen. Nitrate and ammonium nitrogen can be directly absorbed by the plants, but plant absorption of nitrogen is mainly in the form of nitrate nitrogen, and excessive ammonium nitrogen may be toxic to plants. The fertilizers containing nitrate nitrogen can provide nitrogen for plants without conversion, while urea and ammonium nitrogen need to go through the conversion. And it is converted slowly in early spring and nitrogen supply is delayed, so ammonium phosphor nitrate has better effect than ammonium chloride and urea.

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