基于稳定碳同位素技术的华北石质山区2种果农复合模式水分利用研究

在冬小麦返青期、拔节期、扬花-灌浆期和成熟期4个生育期采用稳定碳同位素技术研究华北石质山区4年生株行距3m×4m的核桃-小麦和石榴-小麦复合系统以及单作小麦的水分利用。研究得出核桃间作小麦(WIW)、石榴间作小麦(MIW)和单作小麦(MW)的δ13C和WUE分别为-27.151‰,-26.788‰,-27.338‰和12.780,13.285,12.622mmolC·mol-1H2O。在整个小麦生育期,δ13C和WUE都以石榴间作小麦的最大。WIW和MIW的WUE在拔节期分别比MW显著提高13.84%和10.86%。产量和总生物量都是MW显著高于WIW和MIW。WIW和MIW的总耗水量为185.92mm和175.27mm,分别比MW(253.81mm)少耗26.75%和30.94%,间作系统可显著降低小麦的耗水量,比单作小麦分别减产26.79%和32.19%。产量和生物量呈正相关且两者都与耗水量呈显著正相关,但与WUE相关性不显著,表明小麦耗水越多形成的生物量和产量越多。核桃-小麦和石榴-小麦间作系统在果树的第4年果实收获与清耕果园差异不明显,间作小麦尽管减产但仍有较好的作物收益并且耗水少,可以继续发展林农复合系统,以最大限度地提高经济效益。

A Study on Water Use of Two Fruit Tree-Wheat Intercropping Systems in the Rocky Hilly Region of North China with Stable Carbon Isotope Technique

Trees and crops in an agroforestry system can make the best use of water, nutrients, irradiation and heat. However, competition may occur when the resources are scarce, especially for the water in the semi-arid warm temperate region. Water use of winter wheat (Triticum aestivum) in the walnut(Juglans regia)-wheat and the megranate (Punica granatum)-wheat intercropping systems, and the wheat monoculture field was investigated at seedling establishment, jointing, flowering-filling and maturing growth period of wheat in the rocky hilly area of North China with stable carbon isotope technique. The walnut and megranate were planted in a density of 3 m between plants in the rows and 4 m between rows. The results showed that the δ13C and WUE of wheat in the walnut-wheat and megranate-wheat intercropping as well as the wheat monoculture were-27.151‰,-26.788‰,-27.338‰ and 12.780, 13.285, 12.622 mmol C·mol-1 H2O, respectively. The two parameters were the highest in the megranate-wheat intercropping system. The average WUE of wheat in the walnut and megranate intercropping was obviously higher by 13.84% and 10.86% compared with that in the monoculture wheat at jointing period. The grain yield, total biomass and water use of the monoculture wheat were higher than that ofintercropping wheat. The total water use of walnut, and megranate tree intercropping wheat were 185.92 mm and 175.27 mm, respectively, and 26.75% and 30.94% less than that of monoculture wheat (253.81 mm), suggesting that the intercropping system dramatically decreased water use of wheat. The grain yield of walnut, and megranate tree intercropping wheat was decreased 26.79% and 32.19% in comparison with monoculture wheat. There was a positive correlation between wheat grain yield and the biomass production, and both variables were positively correlated with water use, but had no obvious correlation with WUE, which reflected the more production of wheat with the more water use. In conclusion, in the 4th year walnut and megranate-wheat intercropping systems, there was no obvious difference in fruit harvests of walnut and megranate with or without the wheat intercropping. The wheat in the intercropping system used less water, and had sound returns although the harvest was less than the monoculture wheat. Therefore it is recommended to continue the intercropping implementation in order to gain maximum economic benefit.