easyui合并多个单元格

$('#table-v2').datagrid({
    url: './data/am/data1_table.json',
    pagination: true, //显示分页
    fit: true, //datagrid自适应宽度
    fitColumn: false, //列自适应宽度
    striped: false, //行背景交换
    nowap: true, //列内容多时自动折至第二行
    border: false,
    loadFilter: function (data) {
        console.log('ui');
        console.log(data);
        return data;
    },
    columns: [[
        {field: 'ck', checkbox: true, rowspan:2},
        {field: 'itemid', title: '序号', rowspan:2, width: 80, sortable: true},
        {field: 'productid', title: '编号',rowspan:2,  width: 80, sortable: true},
        {title: '监测数据', colspan: 4},

        {title: '监测数据', colspan: 3},

        {title: '监测数据', colspan: 3}

    ],
        [

            {field: 'describe1', title: '消防车数量', width: 80},

            {field: 'describe2', title: '环境湿度',  width: 80},
            {field: 'describe3', title: '环境温度',  width: 100},           合并的4列
            {field: 'describe4', title: '水压', width: 80},
            {field: 'describe5', title: '开度',  width: 80},
            {field: 'describe6', title: '电池电量',  width: 100},           合并的3列

            {field: 'describe7', title: '开度',  width: 80},
            {field: 'describe8', title: '电池电量',  width: 100}

            {field: 'describe9', title: '开度',  width: 80},                合并的3列
            {field: 'describe10', title: '电池电量',  width: 100}

        ]
    ],
效果如下所示：