种植密度对苜蓿生长及生物量的影响

种植密度作为影响作物产量和品质的重要因素,会造成植物对于光照、水分和养分的竞争。为研究种植密度对苜蓿生长与产量的影响,在日光温室环境下,以紫花苜蓿(Medicago sativa)为材料,设置25、100、400、800、1 500、2 000株·m~(–2),共6个种植密度,对紫花苜蓿的种群密度和生长状况进行了观测。结果表明,各处理播种后15天的平均种植密度分别为25、100、373、745、1 255、1 938株·m~(–2);随着紫花苜蓿的生长,除了低密度(25、100株·m~(–2))处理没有发生植株数量的变化外,其余4个密度处理植株数量均有所减少,即发生不同程度的自疏,至第二茬收获时(播种后第187天)种群数量分别减少为297、571、759、839株·m~(–2)。植株个体的株高、基径和分枝数量随着现存密度的增加呈指数下降;个体生物量与现存密度的关系满足竞争密度效应的幂函数关系,即随着密度的增加而减小。紫花苜蓿单位面积地上生物量符合最终产量恒定法则,然而,随着密度的增加,地下生物量有先增加后减小的趋势

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies