钙水平对大葱生长及氮代谢的影响

摘要

Objectives]The effect of calcium (Ca) on growth and nitrogen metabolism of Welsh onion (Allium fistulosumL.) was investigated to clarify the role of Ca in improving the yield and quality, and provide a theoretical basis for the optimization fertilization technique.[Methods]Welsh onion cultivars ‘Zhaohe’and‘Zhangqiu’ were used as test materials in sand cultural and feild trails. Four Ca2+levels of 0, 4, 6, 8 mmol/L in sand cutural trail and four CaO application rate of 0, 225, 450, 675 kg/hm2in field trail were designed. Different forms of nitrogen and activities of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate dehydrogenase (GDH) in onion leaves were determined during seedling over-summer stage (Jul. 17), vigorous growth stage (Sept. 11) and cauloid forming stage (Oct. 20). The growth, yield and quality of Welch onion were measured at harvest stage (Nov. 13).[Results]With the increase in solution Ca level, plant height, cauloid diameter of potted Welsh onion as well as root and shoot fresh weight were increased significantly, and reached peak in 6 mmol/L Ca level with biomass per plant of 211.13 g. Continue increase to 8 mmol/L, the biomass significantly decreased to 185.83 g. ‘Zhangqiu’ showed significantly higher plant height, cauloid diameter and shoot fresh weight compared to ‘Zhaohe’, while the root fresh weight was not the case. Appropriate Ca application enhanced the activities of GOGAT, GDH, NR and GS dramatically in Welsh onion leaves particularly in the most sensitive vigorous growth stage. The content of NH4+-N, NO3–-N, soluble protein and free amino acid increased with growth stage and reach peak at vigorous growth stage. All the quality-related indexes of two cultivars were highest at 6 mmol/L Ca level, the yield of ‘Zhangqiu’ and ‘Zhaohe’ was significantly increased by 79.94%, 74.42% in 6 mmol/L, respectively, compared to the control. For the field trial, the yields in treatment with CaO of 450 kg/hm2were increased by 12.30%, 19.00%, respectively.[Conclusions]The appropriate application of Ca can enhance the growth, improve enzyme activities of nitrogen metabolism and the contents of different nitrogen forms of Welsh onion, therefore the yield and quality. Comprehensively, the nutrient solution containing Ca of 6 mmol/L and soil CaO supplying at 450 kg/hm2are the most conducive to improve the growth, quality and yield of Welsh onion.%【目的】通过探讨钙对大葱生长及氮代谢的影响，明确钙在提高大葱产量和品质中的作用，为优化大葱施肥技术提供理论依据。【方法】以‘昭和’和‘章丘’大葱为试材，进行了砂培试验和田间试验。用砂培试验营养液钙水平设0、4、6、8 mmol/L 4个处理。于大葱越夏期(7月17日)、叶丛速生期(9月11日)及假茎充实期(10月20日)取大葱叶片测定不同形态氮含量以及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)和谷氨酸脱氢酶(GDH)活性，于收获期(11月13日)测定大葱生长量、产量及品质。田间试验设置0、225、450、675 kg/hm24个水平(以 CaO计)，于收获期(11月13日)测定产量。【结果】砂培大葱株高、茎粗、根及茎叶鲜重均随营养液钙水平提高而显著增加，至钙水平达6 mmol/L时表现较好，单株生长量达211.13 g，钙水平继续增加至8 mmol/L时，单株生长量仅185.83 g，与4 mmol/L的183.29 g无显著差异；除根系鲜重外，‘章丘’大葱株高、茎粗及茎叶鲜重均显著高于‘昭和’大葱。适量增加钙水平亦可显著提高大葱叶片 GOGAT、GDH、NR、GS活性，以叶丛速生期影响最大。大葱叶片铵态氮(NH4+-N)、硝态氮(NO3–-N)、可溶性蛋白、游离氨基酸含量均随营养液钙水平提高而呈先增加后降低，均以叶丛速生期最高。两品种大葱品质相关指标均以钙水平6 mmol/L时最高，8 mmol/L时有所降低。钙水平为6 mmol/L时，盆栽大葱产量显著高于其它处理，‘章丘’和‘昭和’分别较对照增产79.94%和74.42%。大田试验，‘章丘’和‘昭和’大葱均以施用 CaO 450 kg/hm2产量最高，分别较对照提高12.30%、19.00%。【结论】适量施钙可显著促进大葱生长，提高叶片氮代谢酶活性及不同形态氮含量，提高产量及品质。综合分析表明，以营养液钙水平6 mmol/L、土壤施钙450 kg/hm2时最有利于大葱的生长及产量品质的提高。