水浮莲对水稻竞争效应、产量与土壤养分的影响

为了解入侵植物水浮莲在稻田生产中的扩散规律和对水稻农业性状的影响,通过田间水稻田实验,按照de Wit 取代试验方法和添加系列设计方法研究水浮莲与水稻(云稻2 号)混种对植株形态和生物量影响、种间竞争效应、水稻产量以及对土壤养分的影响。结果表明,混种条件下水浮莲母株株高、分蘖数、生物量和开花株数均受到水稻的明显抑制,受到的抑制率显著高于其对水稻的抑制率。水浮莲的种间竞争大于种内竞争(RY 小于1.0)而水稻的种内竞争大于种间竞争(RY 大于1.0),水浮莲混种比例大于和等于1:1 时(RYT大于1.0)与水稻不存在竞争作用,而小于1:1时(RYT 小于1.0)其存在着竞争作用,水浮莲对水稻的竞争力(CB 小于0)小于水稻。混种条件下水稻有效穗数和产量有明显提高,增产比例为3.54%-13.38%。生长过程中水浮莲对土壤钾、磷元素消耗大于水稻,而有机质和氮元素消耗小于水稻;混种条件下水稻明显降低水浮莲对土壤养分消耗,且二者在土壤养分上没有竞争关系。所有这些表明,入侵稻田的水浮莲与水稻生长过程中其形态、生物量等方面都处于劣势,而且一定的水浮莲密度有利于抑制水浮莲对土壤养分的消耗和促进水稻生长繁殖及其产量的提高,因此为满足饲料利用和环境净化,建议在正常耕作稻田中可对水浮莲进行适当的应用。

Competitive effect of Pistia stratiotes to rice and its impacts on rice yield and soil nutrients

To explore the spreading pattern of the invasive plant Pistia stratiotes and its effects on agronomic features of rice, paddy field experiments were conducted to measure the impacts of P. stratiotes on plant morphology, biomass, competitive effect, grain yield, and soil nutrients under mixed cultivation of rice (Yundao 2) with P. stratiotes, utilizing replacement and additive de Wit series. The results showed that in mixed culture, mother ramet plant height, tiller number, biomass, and flowering plant number of P. stratiotes were obviously suppressed, and the inhibition rates were significantly higher than those of rice. The relative yield (RY) of P. stratiotes and rice was clearly lower and higher than 1.0, respectively, showing that the interspecific competition impacts on P. stratiotes were greater than impacts of intraspecific competition, whereas intraspecific competition was higher than interspecific competition in the case of rice. The relative yield total (RYT) of P. stratiotes and rice was significantly higher than 1.0 for a ratio of P. stratiotes to rice of greater than 1:1, demonstrating no significant competition. However, there was serious competition between two plants for a P. stratiotes: rice ratio lower than 1:1. The competitive balance (CB) index of P. stratiotes and rice was significantly less than zero, indicating that P. stratiotes had less competitive ability than rice. In mixed culture, rice grain yield was increased by 3.54%-13.38%, which resulted from increased effective panicle number compared with monoculture (CK). During the growth of P. stratiotes and rice, P. stratiotes consumed more soil potassium and phosphorus than rice, whereas its consumption of soil organic matter and nitrogen was less than rice; soil nutrients absorbed by P. stratiotes was obviously reduced when growing in mixed culture with rice, and there was no competition for soil nutrient utilization between P. stratiotes and rice. All results suggested that morphological and biomass characteristics of P. stratiotes put it at a disadvantage when grown with rice. Moreover, a suitable density of P. stratiotes would prevent its excessive consumption of soil nutrients and at the same time increase growth, reproduction and grain yield of rice. Thus P. stratiotes could be properly grown and applied in cultivated rice fields for the purpose of fodder use and environment purification.