Optimising Hybrid Performance
A crop is considered to have reached a specific stage when 50 of the plants display the typical characteristics of that particular stage.
1st growth stage
Leaf differentiation and emergence
2nd growth stage
Ovule development and pollination
Leaf, root, and stalk growth
3rd growth stage
+/- 80 GDDs, depending on planting date, climate, and soil
- The first leaf emerges on the soil surface. Seedlings are visible along the row.
2 - 3 leaves
- The first leaf has a rounded tip. The seedling lives off the seed reserves.
4-5 leaves | Seedling “weaning”
- The seedling feeds off the recently-emerged seminal roots and crown roots.
- Establishment of the final plant population.
An average 44 GDDs are needed for each new leaf.
8-10 leaves | Tassel and ear shoot initiation
- At 50-percent visible leaves (8 leaves in early hybrids and 10 leaves in late hybrids), all leaves are differentiated and the tassel and future ear are initiated. The plant enters its rapid growth phase.
12 - 14 leaves
- Leaves cover the inter-row space. Leaf area index is close to 1 (1 hectare of leaves per cultivated hectare).
220 GDDs before female flowering
Tassel is visible in the whorl
- The tassel emerges from the leaf whorl. The silks begin to elongate. The number of ovules per row is set.
- The number of potential ears is set.
- The number of ovules which can be pollinated is set.
• Early: 825 to 875 GDDs • Semi-early, flint-dent: 875 to 925 GDDs • Semi-early, dent: 925 to 980 GDDs • Semi-late: 975 to 1000 GDDs • Late: 1000 to 1050 GDDs
- The silks emerge from the ear. The tassel produces pollen. The ovules are pollinated. The leaves have finished growing. The leaf area index is at its maximum.
250 dj après floraison femelle
Kernel abortion threshold
- The cells of albumin (future reservoir of starch) multiply during the three weeks of latent stage which follow the pollination. The increase in kernel weight is low during this period, when the final number of kernels is established. The plant reaches its maximum height.
The dry matter that has been produced is stored in the stalk. The vegetative portion of the plant reaches its maximum weight.
20-24 days needed at the end of this stage, per point of additional dry matter.
Emergence of lentille vitreuse (in vitreous and vitreous-dented varieties) • Emergence of the depression at the top of the kernel (in dented varieties)
- Dry matter accumulates fast inside the kernel. The starch texture evolves, going from milk to wax, then floury and vitreous. The early development of vitreous starch inside the kernel of flinty and flinty-dented varieties indicates a D.M. rate of 25 to 27 percent.
600 to 675 dds after the female flowering.
50 percent kernel moisture
- Kernel growth slows down. This stage is characterized by one third of milk starch in the albumen.
- At 50 percent kernel moisture, the DM of the whole plant is at about 32 percent.
• 640 to 700 dds after the female flowering. • 18 dds needed to decrease kernel moisture by 1 percent.
45 percent kernel moisture
- The kernel reaches 75-80 percent of its maximum weight.
- The stalk and leaf DM supports the growth of the kernels. The leaf index decreases fast.
- The whole plant yield is maximum.
Feed harvest between 28 and 35 percent DM/whole plant.
850 to 950 dds after female flowering, depending on the earliness.
32 percent kernel moisture
- The maize plant has reached physiological maturity. Kernel weight is at its maximum. The black layer appears at the kernel base, indicating that the nutrient transfer is over. Starch is either completely floury or flinty. The plant has a dried-out aspect.
Grain harvest – if possible – after 35 percent moisture, or earlier for maize used for .