NITROGEN RATES AND SIDE-DRESSING TIMING ON SWEET CORN SEED PRODUCTION AND PHYSIOLOGICAL POTENTIAL

ABSTRACT Sweet corn is an important crop because of its seeds with high total sugar and low starch contents. As common corn, this group requires an adequate amount of nitrogen to reach high yields. However, the studies on nitrogen and sweet corn are performed for ear yield instead of seed yield. As seeds are the main propagation method for this species, we proposed to evaluate the effects of nitrogen rates as side-dressing at different plant stages of a sweet corn seed production. Sweet corn seeds (variety BR 400) were sown in Latosol (Oxisol), and a 3×2+1 factorial scheme was designed with three nitrogen rates (40, 80, and 120 kg ha-1) at two plant stages (V6 and R1) plus the control (no nitrogen side-dressing). The evaluated variables were seed yield, protein content, P and Zn contents, germination, and vigor rates. We concluded that nitrogen applied at a rate of 120 kg ha-1 at V6 increases seed yield and maintains unaltered the protein content in seeds of sweet corn (BR 400 variety). Neither germination nor seed vigor increases when nitrogen rates are increased or administered at different stages of plant development. We also noted a slight decrease in P content or an increase in Zn content of seeds at low nitrogen rates; however, they are insufficient to promote changes in the physiological potential of sweet corn seeds.

摘要：甜玉米因种子总糖含量高、淀粉含量低而成为一类重要作物。与普通玉米一致，该类作物需充足氮肥以实现高产，但当前关于氮肥与甜玉米的研究多以果穗产量为考察目标，而非种子产量。鉴于种子是该物种的主要繁殖方式，本研究拟评估不同生育期追施氮肥（side-dressing）对甜玉米种子生产的影响。供试甜玉米品种为BR 400，种植于砖红壤（Oxisol），试验采用3×2+1因子设计：设置3个氮肥施用量水平（40、80、120 kg·ha⁻¹）、2个追肥生育期（V6与R1），并设置不追施氮肥的对照组。本研究测定的指标包括种子产量、蛋白质含量、磷（P）与锌（Zn）含量、发芽率及活力指标。研究结果表明，在V6生育期施用120 kg·ha⁻¹氮肥可提升甜玉米（品种BR 400）的种子产量，且不会改变其种子蛋白质含量；无论提高氮肥施用量，还是在不同生育期追肥，均无法提升种子发芽率与活力。本研究同时发现，低氮肥施用量下甜玉米种子的磷含量略有降低、锌含量略有升高，但上述变化均不足以改变甜玉米种子的生理潜力。