休闲期深松配施氮肥对旱地土壤水分及小麦籽粒蛋白质积累的影响

为探索旱地小麦休闲期蓄水保墒及其配套施肥技术,2009—2011年连续2个小麦生长季,在山西闻喜县进行了休闲期深松或无耕作条件下低(75 kg hm–2)、中(150 kg hm–2)、高(225 kg hm–2)施氮水平的田间试验,以明确深松处理配合施氮对土壤水分、籽粒蛋白质形成的影响。结果表明,深松处理可提高播前土壤蓄水量,尤其是深层土壤(60~160 cm)蓄水量,欠水年和丰水年分别提高12%~34%、10%~22%。深松处理后,籽粒谷氨酰胺合成酶(GS)、旗叶谷氨酸合酶(GOGAT)、低氮和中氮条件下籽粒GOGAT、籽粒谷丙转氨酶(GPT)活性均提高;籽粒蛋白质产量和球蛋白含量,及丰水年谷蛋白含量和谷醇比也提高。随施氮量增加,开花期20~200 cm土壤蓄水量呈下降趋势,但籽粒GS、灌浆中后期旗叶GOGAT、灌浆后期籽粒GPT活性均上升,籽粒蛋白质及其组分含量提高,中氮条件下籽粒谷醇比最高。施氮量对深松处理开花期深层土壤蓄水量、籽粒蛋白质产量、籽粒GS和GPT活性有较大调控效应。深松配施氮肥条件下,丰水年开花期土壤水分与籽粒清蛋白、谷蛋白、蛋白质含量关系密切,而欠水年开花期土壤水分与谷醇比关系密切。氮代谢酶主要影响籽粒球蛋白含量、蛋白质产量的积累,丰水年还影响籽粒谷蛋白含量和谷醇比的提高。总之,旱地小麦休闲期深松蓄水效果好;配施氮量225 kg hm–2有利于提高籽粒蛋白质及其组分含量,在欠水年施氮量150 kg hm–2有利于提高籽粒蛋白质产量及谷醇比。

Effect of Subsoiling in Fallow Period and Nitrogen Application on Soil Moisture and Grain Protein Accumulation in Dryland Wheat

The objective of this study was to explore a technique to increase and maintain soil moisture of dryland through subsoiling during fallow period (SS) and the proper nitrogen (N) application in wheat production. In a two-year field experiment carried out in Wenxi County of Shanxi Province, China from autumn 2009 to summer 2011, we tested soil moistures in different soil layers, protein content and its components in grain, and activities of enzymes related to protein accumulation during grain filling after SS and non-tillage practice (CK) in combination with the applications of low (LN, 75 kg ha^-1), medium (MN, 150 kg ha^-1), or high (HN, 225 kg ha^-1) N. Before sowing, the soil moistures in 0-300 cm soil layers under SS condition were higher than those under CK condition, especially in 60–160 cm soil layers, which were increased by 12%–34% in dry year and 10%–22% in humid year. Under SS condition, the activities of protein-related enzymes increased, such as glutamine synthetase (GS) in grain, glutamate synthase (GOGAT) in flag leaf, and GOGAT in grain in LN and MN treatments, and glutamic acid-pyruvate transaminase (GPT) in grain. In mature grains, the globulin content and protein yield in SS treatment were increased compared with CK, and Glutenin content and glutenin/gliadin ratio in humid year also increased in SS. The soil moisture in 20–200 cm soil layer at anthesis stage showed a decrease trend with the increase of nitrogen application level; however, the GS activity in grain, GOGAT activity in flag leaf at middle to late filling stage , GPT activity in grain at late filling stage were enhanced, and the contents of protein and its components in grain were increased. The glutenin/gliadin ratio in grain was the highest in MN treatment. Nitrogen application had obvious effects on soil moisture in the deep soil layer at anthesis, also on protein yield, GS and GPT activities in grain under SS condition. Under SS plus N application condition, soil moisture at anthesis was closely correlated with grain albumin, glutenin, and protein content in humid year and with glutenin/gliadin ratio in dry year. In conclusion, subsoiling during fallow period is an effective method to maintain soil moisture in dryland; N application at 225 kg ha^-1 has a positive effect on increasing contents of grain protein and its components, whereas N level of 150 kg ha^-1 is favorable for high protein yield and glutenin/gliadin ratio in grain in dry year.