Corn Growth Staging Using the Leaf Collar Method

Lindsay Overmyer Author

05/11/2021 Added

117 Plays

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Corn growth staging using the leaf collar method provides an overview of staging corn from emergence (VE) to the abscission layer (R6).

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[00:00:09.350]Corn at Growth Staging Using
[00:00:11.030]the Leaf Collar Method.
[00:00:13.950]Understanding the growth stages
[00:00:15.720]of corn Zea mays is important
[00:00:17.810]for management decisions regarding fertilizer,
[00:00:20.850]irrigation, and pesticide applications.
[00:00:24.060]The leaf collar staging method is the most
[00:00:26.690]commonly used method, as it is used by many in the industry.
[00:00:31.040]For this method, plant growth stages are broken down
[00:00:34.890]into two main phases, vegetative and reproductive.
[00:00:39.670]During vegetative growth, the leaf collar method
[00:00:42.290]of staging corn involves counting leaves
[00:00:44.950]showing visible collars.
[00:00:46.940]A leaf collar is located at the base of the leaf blade
[00:00:50.800]where it wraps around the stem,
[00:00:52.590]and it can be identified as a visually distinct band.
[00:00:57.000]Stages during vegetative growth will include a V
[00:01:00.650]for the vegetative phase,
[00:01:02.390]and the number of leaf collars visible on the plant.
[00:01:05.900]Once the ear and its silks are visible,
[00:01:08.200]the plant has reached the reproductive growth phase
[00:01:10.900]and staging on the plant focuses
[00:01:13.180]on ear and kernel development on the primary ear.
[00:01:16.680]The primary ear is the uppermost ear on the plant.
[00:01:20.700]When the corn seed germinates and the coleoptile emerges
[00:01:24.070]through the soil's surface,
[00:01:25.480]the stage is vegetative emergence or VE.
[00:01:28.890]When the leaf collar of the first true leaf is visible,
[00:01:32.230]the stage is V1.
[00:01:33.930]This first leaf has a rounded tip,
[00:01:36.100]but all remaining leaves produced will have a pointed tip.
[00:01:40.160]This is a V5-stage plant,
[00:01:42.900]as the leaf collars of five leaves are visible.
[00:01:46.820]The growing point of corn is
[00:01:49.190]below the soil's surface until V6.
[00:01:52.690]For the later stages of corn,
[00:01:54.830]it may be difficult to establish the exact number of leaves
[00:01:58.980]because the lower leaves may have dried up and fallen off.
[00:02:03.270]Under these conditions, if leaf stage accuracy is critical,
[00:02:07.250]the exact stage can be determined by dissecting the stalk
[00:02:11.130]and counting the thickened internal leaf nodes.
[00:02:15.310]The vegetative tassel stage
[00:02:17.490]or VT is the last vegetative stage.
[00:02:21.220]The plant is at VT when all branches
[00:02:24.240]of the tassel are fully visible
[00:02:26.570]and not held within the upper most leaves.
[00:02:30.510]The first stage of the reproductive phase
[00:02:33.170]is reproductive silking or R1.
[00:02:36.250]This occurs when the silks extend outside the ear husk.
[00:02:40.780]This is a critical time for the plant
[00:02:43.000]because pollination and fertilization occur.
[00:02:46.410]Pollination is the transfer of pollen grains,
[00:02:49.630]the male reproductive cell,
[00:02:51.610]from the tassel to the silks, the female reproductive cell.
[00:02:55.340]Every silk is attached to an ovary and is receptive
[00:02:58.680]to pollen for at least five days after emerging.
[00:03:02.250]The first silks to emerge are those attached
[00:03:05.060]to potential kernels at the base of the ear.
[00:03:08.420]The silks at the tip of the ear emerge later,
[00:03:12.100]and if they do not receive pollen,
[00:03:14.120]they will not develop into an embryo.
[00:03:16.850]The R2 stage is referred to as the blister stage
[00:03:20.300]because the top of the kernels resemble a blister
[00:03:23.910]where the silks were attached.
[00:03:25.690]R3 is known as the milk stage
[00:03:28.430]because the kernels are filled with a milky material,
[00:03:31.690]and when pressure is applied,
[00:03:33.350]the kernel will easily pop and expose its milky contents.
[00:03:37.920]The dough stage or R4 is identified
[00:03:41.350]when the interior contents
[00:03:43.070]of the kernel has a consistency similar to dough.
[00:03:46.790]At dent, or reproductive stage five, or R5,
[00:03:50.840]the moisture content in the kernel has declined
[00:03:53.630]to about 60% and this results in a dent in most kernels.
[00:03:59.500]However, dry matter content of the kernel continues
[00:04:03.610]to accumulate considerably
[00:04:05.420]as the kernels continue to lose moisture.
[00:04:08.560]Physiological maturity or R6 is the final gross stage
[00:04:12.580]of corn, and kernel moisture content is about 30%.
[00:04:17.340]At R6, an abscission layer, also called black layer,
[00:04:21.610]has formed at the base of the kernel,
[00:04:24.150]and the kernel does not receive further nutrients
[00:04:26.780]from the plant.
[00:04:28.280]Understanding these stages
[00:04:29.750]of growth is important for management decisions.

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Tags:
corn
corn growth stages
leaf collar method
maize
zea mays

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Corn Growth Staging Using the Leaf Collar Method

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