Protecting the Corn Plant at Flowering Stage
This time around, I will discuss the late whorl to flowering stages. Al. though the period covering these stages is not as long as the early vegetative phase, it is a very critical stage that could make or break your hybrid’s performance. The recent drought in Northern Luzon this, year is a testament of how the gains of proper care in the early stages can go to waste when severe stress (lack of moisture) coincides with the pollination period. Healthy looking crops in drought-stricken areas of Isabela and Cagayan had resulted in barren plants or poorly filled ears. Farmers were devastated by the very low grain yield at a time when grain prices are attractive.
LATE WHORL STAGE
Corn plants at this stage undergo rapid nutrient and dry matter accumulation. The leaves develop much faster while ear size, number of kernel rows, total number of kernels per ear are also being determined. In addition, brace roots start to develop from the lower nodes to provide additional anchorage. Any stress at this time could only mean a permanent and irreversible damage to the plant leading to poor grain-filling or barren plants.
All these indicators imply the need for more water and complete set of nutrients tq keep up with the various processes. Phosphorus (P) and potassium (K) is badly needed at this point while sufficient levels of soil moisture should ensure nutrient uptake and proper plant metabolism.
TASSELING AND SILKING STAGE
At this stage, the corn plant has achieved its maximum height and number of leaves. The plant enters the tasseling stage when the tassel branches spread out. Silking is expected to occur 2-3 days later and when pollens have been continuously shed prior to silk emergence. Pollen shedding occurs mid-morning and/or at night time and may continue for about a week or two. A successful pollination happens when a pollen grain is dropped and attached to a silk after which it fertilizes the ovule and becomes a corn grain. Each ovule is a corn grain resulting from a successful fertilization. (The silk continues to elongate until it is pollinated. Once the ovule is fertilized, the silk is easily shed from the ear). Kernel-setting can be concluded in 2-3 days.
In comparison to the late whorl stage, the tasseling/silking stage in corn is more sensitive to environmental stresses. Severe drought can lead to a widening gap between the period of pollen shedding and silk emergence. Non-synchrony of these two will lead to poor grains filling. In extreme cases, pollens and silks are desiccated by heat leading to totally barren ears.
It was also observed that too much rain during this period can interfere with pollen shedding. Low sunlight and reduction of leaves (or leaf area) can also lead to, aborted grains despite a successful polination.
MANAGEMENT CONSIDERATIONS
1. It is important that a sound and balance nutrient management program is in place prior to ear development (2:1:2 NPK ratio). Late application or lack of these nutrients, in particular P and K, could lead to poor ear formation.
2. Avoid hilling-up at this stage since the crops may be too tall already or that roots may be unintentionally damaged.
3. Provide adequate water. Pollens and silks are the most sensitive to moisture stress especially under a dry and warm
growing condition. If budget is a limitation, prioritize irrigation schedule at this time.
4. In rainfed areas, adopt a combination of strategies to combat drought. These could range from proper hybrid selection to balance nutrient management and optimum planting density. Remember that healthier crops have a better tolerance to stress than weak plants.
5. Avoid water logging to minimize risk of stalk rots. Poor soil drainage can likewise interfere with flowering and grain formation.
6. Watch out for corn borers and other leaf-feeding insects, if you opt to use conventional hybrid corn. Better yet, choose insect-protected hybrids to eliminate this problem.