Yang Rui, Wang Zhuangzhi, Fahad Shah, Geng Shiying, Zhang Chengxiang, Harrison Matthew Tom, Adnan Muhammad, Saud Shah, Zhou Meixue, Liu Ke, Wang Xiaoyan
Hubei Collaborative Innovation Center for Grain Industry, School of Agriculture, Yangtze University, Jingzhou, China.
Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, China.
Front Plant Sci. 2022 Jul 22;13:959784. doi: 10.3389/fpls.2022.959784. eCollection 2022.
Yields of wheat crops that succeed rice paddy crops are generally low. To date, it has been unclear whether such low yields were due to rice paddies altering soil physical or mineral characteristics, or both. To investigate this quandary, we conducted field experiments in the Jianghan Plain to analyze differences in the spatial distribution of wheat roots between rice-wheat rotation (RW) and dryland-wheat rotations (DW) using a range of nitrogen treatments. Dryland wheat crops were preceded by either dryland soybean or corn in the prior summer. Biomass of wheat crops in RW systems was significantly lower than that of DW for all N fertilizer treatments, although optimal nitrogen management resulted in comparable wheat yields in both DW and RW. Soil saturated water capacity and non-capillary porosity were higher in DW than RW, whereas soil bulk density was higher in RW. Soil available nitrogen and organic matter were higher in DW than RW irrespective of N application, while soil available P and K were higher under RW both at anthesis and post-harvest stages. At anthesis, root length percentage (RLP) was more concentrated in surface layers (0-20 cm) in RW, whereas at 20-40 cm and 40-60 cm, RLP was higher in DW than RW for all N treatments. At maturity, RLP were ranked 0-20 > 20-40 > 40-60 cm under both cropping systems irrespective of N fertilization. Root length percentage and soil chemical properties at 0-20 cm were positively correlated ( = 0.79 at anthesis, = 0.68 at post-harvest) with soil available P, while available N ( = -0.59) and soil organic matter ( = -0.39) were negatively correlated with RLP at anthesis. Nitrogen applied at 180 kg ha in three unform amounts of 60 kg N ha at sowing, wintering and jointing resulted in higher yields than other treatments for both cropping systems. Overall, our results suggest that flooding of rice paddies increased bulk density and reduced available nitrogen, inhibiting the growth and yield of subsequent wheat crops relative to rainfed corn or soybean crops.
继稻田作物之后种植的小麦作物产量通常较低。迄今为止，尚不清楚这种低产量是由于稻田改变了土壤物理特性还是矿物质特性，抑或是两者皆有。为了探究这一难题，我们在江汉平原进行了田间试验，采用一系列氮肥处理来分析稻麦轮作（RW）和旱地小麦轮作（DW）之间小麦根系空间分布的差异。旱地小麦作物的前茬作物为前一年夏季种植的旱地大豆或玉米。对于所有氮肥处理，RW系统中小麦作物的生物量均显著低于DW系统，不过最佳氮肥管理使DW和RW的小麦产量相当。DW的土壤饱和含水量和非毛管孔隙度高于RW，而RW的土壤容重更高。无论是否施氮，DW的土壤有效氮和有机质均高于RW，而在花期和收获后阶段，RW的土壤有效磷和钾含量均更高。在花期，RW的根长百分比（RLP）更集中在表层（0 - 20厘米），而在20 - 40厘米和40 - 60厘米处，所有氮肥处理下DW的RLP均高于RW。在成熟期，无论施肥与否，两种种植系统下的RLP均表现为0 - 20厘米＞20 - 40厘米＞40 - 60厘米。0 - 20厘米处的根长百分比与土壤化学性质呈正相关（花期时r = 0.79，收获后r = 0.68），与土壤有效磷相关，而有效氮（r = -0.59）和土壤有机质（r = -0.39）在花期与RLP呈负相关。两种种植系统下，在播种期、越冬期和拔节期分三次等量施氮180千克/公顷，每次60千克/公顷，其产量均高于其他处理。总体而言，我们的研究结果表明，稻田淹水增加了土壤容重并降低了有效氮含量，相对于雨养玉米或大豆作物，抑制了后续小麦作物的生长和产量。
