Do you understand the different growth phases of your maize crop?
Did you know each phase has different nutritional requirements?
Are you following the best protocols for each phase to boost your yields?
First, a refresher on the maize plant:Every maize plant has both male and female organs. The male organ, known as the tassel, emerges from the top of the plant after all the leaves have emerged. The tassel has many small flowers, each of which releases pollen grains. The female organ is called the ear, of which there can be more than one. The immature ear consists of the cylindrical cob with eggs that develop into kernels after pollination. From each egg, a hair-like structure called a silk grows and emerges from the husk. Pollination occurs when pollen falls on the exposed silk, and the male sex cell grows down the silks to a single egg and fertilisation occurs. The fertilised eggs develop into the kernels.
The Lifecycle of Maize
The lifecycle of the maize plant has two key developmental phases: the vegetative phase (V phase) and the reproductive phase (R phase)
Note: Vegetative and reproductive stages are determined on a whole-field basis when at least 50% or more of the plants have reached or are beyond a particular stage.
Vegetative (V Phase)
Vegetative growth stages are from emergence (VE stage) to tasseling (VT stage), with each V stage based upon the number of visible leaf collars. For example, 1 visible leaf collar is V1 stage, and V4 stage would be 4 visible leaf collars. The period between V6 (six leaves with visible collars) and VT (tassel) is often referred to as the period of rapid growth.
NOTE: While water stress prior to the V4 to V5 growth stages would probably cause little yield loss if plants survive, at V6, the development of tassels and ears starts, so water stress can cause more damage than at the seedling stage, with progressively more damage the closer the stress occurs to tasseling
VT is the last stage of the vegetative state, where the plant has reached its full height and tassels emerge. Spraying of any products must be avoided at this stage so as not to damage the pollen and influence pollination.
VE - EmergenceThe shoot has emerged from the soil.
V1 - First leafLowest leaf has a visible collar; this leaf has a rounded tip
V2 - Second leafTwo of the lowest leaves have a visible collar, the second and subsequent leaves have pointed tips.
V(N) - Nth leafnth leaf – “n” leaf collars present. Count the collars to know the V stage.
VT - TasselThe lowest branch of the tassel is visible.
Reproductive (R stage)
Once the plant has silks visible outside of the husks it has reached the first reproductive phase (R1)
R1 - SilkingWhen silks emerge from the eat to receive pollen and begin the fertilisation process. This comes directly after and must coincide with tasseling for pollination to occur.
R2 - BlisterKernels resemble ‘blisters’ with clear liquid
R3 - MilkKernels develop a buttery yellow colour and are full of milky white fluid
R4 - DoughKernels gain consistency and size, but remain soft and very moist.
R5 - DentingKernels are fully dented and hard starch begins forming at the crown of kernels.
R6 - Physiological MaturityKernels at maximum dry matter accumulation; a “black layer” will form at kernel base (2-3 days after physiological maturity).
What are the Nutrient Requirements at the Different Stages of Maize Growth?
When preparing the soil and planting:
Nitrogen to promote strong early growth.
Phosphorus and zinc to maximise root development and shoot growth.
Calcium to improve root growth and strengthen plant cells.
VE (Emergence) to V6 (Stem Extension)
Nitrogen – apply your main doses here to drive growth – sufficient N will support stem extension.
Potassium and phosphorus – to promote leaf growth.
Sulfur and magnesium – to maintain vigorous leaf growth and build plant supplies.
Zinc and boron – to maintain good new growth.
V6 & VT (Stem Extension to Tasseling)
Potassium – for yield and protein synthesis.
Nitrogen – in reduced amounts to maintain protein production.
Magnesium and sulfur plus micronutrients – to maintain strong leaf growth, canopy development and grain proteins.
R1 to R6 (Reproductive Growth)
Potassium – to maximize growth and yields.
Nitrogen – to ensure good protein levels and to balance potassium.
Boron – pollen tube growth and grain set.
Zinc – to sustain high uptake during grain filling.
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