乳线是判定玉米成熟度的重要指标之一, 为明确灌水和施氮对制种玉米种子乳线发育的影响, 以‘郑单958’和‘先玉335’制种玉米为研究对象, 设置充分灌溉(6 000 m3·hm-2, W6000)、中度胁迫(4 500 m3·hm-2, W4500)、重度胁迫(3 000 m3·hm-2, W3000)3个灌水梯度, 不施氮[0 kg(N)·hm-2, N0]、中氮[225 kg(N)·hm-2, N225]、高氮[450 kg(N)·hm-2, N450]3个施氮水平, 研究不同水氮应用对制种玉米种子乳线发育进程、籽粒含水量、百粒重、籽粒脱水和灌浆速率的影响。结果表明, 不同制种组合在不同水氮条件下种子乳线发育表现出明显差异; 不同水氮条件下‘郑单958’乳线发育进程历时18~24 d, 较‘先玉335’的33~36 d短; 随灌水量增加, ‘郑单958’种子乳线发育有延迟趋势, 而‘先玉335’种子乳线受灌水量影响不显著; 在乳线同一发育阶段, 灌水和施氮均对籽粒含水量无显著影响, 百粒重均表现为施氮处理显著高于不施氮; 不同灌水处理间, ‘郑单958’种子在重度胁迫条件下的脱水速率显著高于中度胁迫和充分灌溉, 施氮量间无显著差异, ‘先玉335’种子脱水速率各灌水量间无显著差异; ‘郑单958’种子的灌浆速率各灌水处理间无显著差异, 充分灌水条件下, 不施氮处理灌浆速率显著高于施氮处理, 而‘先玉335’灌浆速率随灌水量增加而增加, 同一灌水条件下均是中氮处理高于不施氮和高氮处理; ‘郑单958’种子每脱水1%, 籽粒百粒重增加幅度在0.37~0.88 g, 而‘先玉335’在0.43~1.34 g。因此, ‘郑单958’种子乳线发育受灌水影响显著, 水分亏缺致使种子脱水加速, 乳线进程加快; ‘先玉335’种子乳线发育受氮素影响显著, 氮素不足和过量均影响种子灌浆, 延迟乳线发育。
The milk line is an important indicator for the determination of the degree of maize maturity. To know the effect of irrigation and nitrogen on milk line development of maize seed, a field experiment involving two maize genotypes (‘ZD958’ and ‘XY335’) was conducted. The experiment included three irrigation treatments (copious irrigation, 6 000 m3·hm-2, W6000; moderate stress irrigation, 4 500 m3·hm-2, W4500; and severe stress irrigation, 3 000 m3·hm-2, W3000) and three levels of nitrogen application [no nitrogen application, 0 kg(N)·hm-2, N0; moderate nitrogen application, 225 kg(N)·hm-2, N225; and moderate-to-high nitrogen application, 450 kg(N)·hm-2, N450]. The milk line development process, kernel moisture, 100-seed weight, dehydration rate and filling rate of maize seeds under different irrigation and nitrogen treatments were investigated. The results showed that milk line development of maize seeds of different varieties was significantly affected by different irrigation and nitrogen levels. Milk line development of ‘ZD958’ seed was 18–24 days and that of ‘XY335 was 33–36 days under different treatments. With increasing irrigation rate, milk line development of ‘ZD958’ seed was longer while that of ‘XY335’ seed was not affected by irrigation. There was no significant difference in seed moisture among treatments at the same stage of milk line development. The 100-grain weight of seed under nitrogen application treatments was significantly higher than that under no nitrogen application treatment. Also the dehydration rate of ‘ZD 958’ seed under severe stress irrigation was significant higher than that under other irrigation treatments. However, there was no difference in dehydration rates under different rates of nitrogen. Also the dehydration rate of ‘XY335’ seed was not affected by irrigation rate. There was no significant difference in filling rate of ‘ZD958’ seed under different irrigation rates. The filling rate of ‘ZD958’ seed under no nitrogen application and copious irrigation was significantly greater than that under nitrogen application. The filling rate of ‘XY335’ seed significantly increased with increasing irrigation rate. For the same irrigation rate, the filling rate of ‘XY335’ seed under moderate nitrogen application was significantly higher than that under other nitrogen rates. With 1% decrease in moisture of ‘ZD958’ seed, 100-grain weight increased by 0.37–0.88 g against that (0.43–1.34 g) for ‘XY335’ seed. Therefore, milk lime development of ‘ZD958’ seed was affected significantly by irrigation. The dehydration rate of seed increased with increasing stress irrigation application, resulting in relatively shorter milk line development. Nitrogen significantly affected milk line development of ‘XY335’ seed. Also the filling rate of the seed was affected with short or excessive nitrogen application. This led to a relatively longer milk line development.