华北低平原不同播种期春玉米的产量表现及其与气象因子的通径分析

针对华北地区种植春玉米面临的灌浆期高温胁迫问题，2011—2012年在河北省吴桥县开展了2个春玉米品种(郑单958播种于2011年，金海5号播种于2012年)的播期试验，以探讨气象因子与玉米产量间的关系，为通过调整播种期减轻春玉米灌浆期的高温胁迫提供理论依据。结果初步表明，不同播种期使春玉米灌浆时期发生变化，因而灌浆期气象因子特征表现出差异。4月上旬播种与其他播种期处理相比，春玉米灌浆期光水资源丰富，降雨量增加5.0~47.4 mm，日照时数增多41.0~70.0 h、气温日较差大0.2~0.6℃，但是，高温胁迫严重(≥33℃天数多达15 d，日均温高达28.4℃)；5月中旬播种的玉米灌浆期高温胁迫轻（≥33℃天数仅有8 d，日均温平均26.0℃），而光水资源相对充足；4月中旬、4月下旬和5月上旬播种的玉米灌浆期高温胁迫相对严重；5月下旬播种的玉米灌浆期高温胁迫相对较轻，但阴雨寡照严重。两年的籽粒产量由高到低的播种期依次是，4月上旬、5月中旬、5月上旬、4月下旬、4月中旬、5月下旬；郑单958和金海5号在4月上旬播种的产量分别达9912 kg hm^-2和11 046 kg hm^-2，在5月中旬播种的产量分别达9906 kg hm^-2和10 852.5 kg hm^-2，其他4个播种期的产量比前两个播种期低6.0%~28.2%。通径分析表明，4月上旬播种的玉米灌浆期气温日较差大、光照时数长，对千粒重和穗粒数的直接正效应大，从而缓解了高温胁迫负效应；5月中旬播种的玉米产量较高是因为躲避了灌浆期高温胁迫，但气温日较差和日照时数的正效应比4月上旬播种期的低，因此比4月上旬播种的产量低；4月中旬、4月下旬、5月上旬、5月下旬各播种处理的千粒重和穗粒数受高温胁迫或阴雨寡照影响较大，且气温日较差和光照时数正效应较小，产量下降明显。针对华北地区种植春玉米面临的灌浆期高温胁迫问题，2011—2012年在河北省吴桥县开展了2个春玉米品种(郑单958播种于2011年，金海5号播种于2012年)的播期试验，以探讨气象因子与玉米产量间的关系，为通过调整播种期减轻春玉米灌浆期的高温胁迫提供理论依据。结果初步表明，不同播种期使春玉米灌浆时期发生变化，因而灌浆期气象因子特征表现出差异。4月上旬播种与其他播种期处理相比，春玉米灌浆期光水资源丰富，降雨量增加5.0~47.4 mm，日照时数增多41.0~70.0 h、气温日较差大0.2~0.6℃，但是，高温胁迫严重(≥33℃天数多达15 d，日均温高达28.4℃)；5月中旬播种的玉米灌浆期高温胁迫轻（≥33℃天数仅有8 d，日均温平均26.0℃），而光水资源相对充足；4月中旬、4月下旬和5月上旬播种的玉米灌浆期高温胁迫相对严重；5月下旬播种的玉米灌浆期高温胁迫相对较轻，但阴雨寡照严重。两年的籽粒产量由高到低的播种期依次是，4月上旬、5月中旬、5月上旬、4月下旬、4月中旬、5月下旬；郑单958和金海5号在4月上旬播种的产量分别达9912 kg hm^-2和11 046 kg hm^-2，在5月中旬播种的产量分别达9906 kg hm^-2和10 852.5 kg hm^-2，其他4个播种期的产量比前两个播种期低6.0%~28.2%。通径分析表明，4月上旬播种的玉米灌浆期气温日较差大、光照时数长，对千粒重和穗粒数的直接正效应大，从而缓解了高温胁迫负效应；5月中旬播种的玉米产量较高是因为躲避了灌浆期高温胁迫，但气温日较差和日照时数的正效应比4月上旬播种期的低，因此比4月上旬播种的产量低；4月中旬、4月下旬、5月上旬、5月下旬各播种处理的千粒重和穗粒数受高温胁迫或阴雨寡照影响较大，且气温日较差和光照时数正效应较小，产量下降明显。

Path Analysis between Yield of Spring Maize and Meteorological Factors at Different Sowing Times in North China Low Plain

In order to study high temperature stress problem of spring maize at grain filling stage in North China Plain, an experiment was conducted using two varieties (Zhengdan 958 and Jinhai 5) sown in six sowing times in Wuqiao County, Hebei Province. We investigated the relationship between meteorological factors and maize yield, hoping to find the evitable sowing time to avoid high temperature stress at grain filling stage . Preliminary results showed that meteorological factors during grain filling stage were different when the sowing time was different. Compared with other sowing time, the treatment with sowing time of early April had more than 5.0–47.4 mm of rainfall, more than 41.0–70.0 h of sunshine, and 0.2–0.6°C of diurnal temperature , but the most serious high temperature stress ( ≥33°C days and mean daily temperature up to 15 d and 28.4°C respectively). Compared with other sowing time, the treatment with sowing time of mid May had weak high temperature stress (≥33°C days and mean daily temperature up to 8 d and 26.0°C respectively), but more rainfall, sunshine hours and diurnal temperature range, that of Mid April, late April and early May had more serious high temperature stress. The sowing treatment of late May had weaker high temperature stress, but more rainfall, less sunshine hours and diurnal temperature range. The order of grain yield for different sowing times from high to low was early April, mid May, early May, late April, mid April, late May. Yield of Zhengdan 958 and Jinhai 5 was up to 9912.0 kg ha^-1 and
11 046.0 kg ha^-1 in early April respectively, 9906.0 kg ha^-1 and 10 852.5 kg ha^-1 in mid May respectively. Yield of the other four sowing times was 6.0%–28.2% lower than that of early April and mid May. The result of path analysis showed that the yield of spring maize sown in early April was the highest, due to its higher diurnal temperature range and sunshine hours, resulting in the greater direct positive effects on 1000-grain weight and grain number per ear than those of other sowing treatments from flowering to maturity, and relieving the negative effect of high temperature stress. The yield of spring maize sown in mid May was higher than that of other sowing treatments (except sown in early April), because of avoiding high temperature stress, increasing 1000-grain weight and grain number per ear, while its lower diurnal temperature range and sunshine hours led to lower yield compared with that sown in early April. High temperature stress or cloud and drizzle had higher negative effect on 1000-grain weight and grain number per ear, and diurnal temperature range and sunshine hours had lower positive effect on yield in other sowing date (mid April, late April, early May, and late May).