Wheat vernalization and small grain project report

Reagan NolandExtension Agronomist

West Region Virtual Wheat Tour – May 7, 2020

Winter wheat requires a “chilling” period in order for timely and uniform reproductive growth to occur.

Temperatures need to be between 32 and 45 F.

Temperatures below freezing do not count!

Requirement generally ranges 3 to 6 weeks (500 to 1000 hours) for varieties grown in Texas.

Chilling hour accumulation starts as soon as the seed imbibes with water (before it sprouts).

What is vernalization?

Wheat does NOT flower as soon as a vernalization requirement is met.

Most of our varieties are also photoperiod sensitive.

As days get longer, reproductive growth occurs faster.

Vernalization requirement and maturity are often correlated, but one does not necessarily cause the other.

Timing of maturity also depends on photoperiod sensitivity of the variety.

When does wheat flower?

Sparse or inconsistent head emergenceReduced head size Inconsistent rates of maturity within the fieldThe entire crop may remain vegetative.

Impacts of poor vernalization

Much wheat was planted late Some wheat did not emerge until late December or early January Winter was warmer than normal

2019-2020 Situation

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30-yr Average Precipitation Precipitation (2019-2020)30-yr Average Temperature Average Temp (2019-2020)

We can forecast vernalization issues based on cumulative chilling hours to date Can get a head-start on contingency plans.

Forecasting Issues

Germination Date

Cumulative chilling hours

Actual Projected

Feb - 7 Mar - 1 Apr - 1

10/15/2019 726 844 918

11/1/2019 647 765 839

11/15/2019 549 667 741

12/1/2019 460 578 652

12/15/2019 360 478 552

1/1/2020 247 365 439

Used variety testing data from multiple sites across the state in 2016-2017 (a bad vernalization year).

Assessing variety differences

SitePlanting

date

Cumulative chilling hours since planting

Yield (bu/ac)

Ending Feb-7

Ending Apr-1

TAM 114

SY Grit SY FlintWB

4515Gallagher

SY Razor

TAM 401

Wharton 11/17/2016 174 183 0.4 0.3 0.7 2.9 5.3 6.6 22.4

College Station 11/3/2016 195 215 4.5 9.5 9 9.2 13 - 17

Uvalde 11/28/2016 211 239 22 6.9 22.1 19.4 54.3 38 41.6

McGregor 11/21/2016 312 396 2.9 13.2 12.1 17.6 24.2 - 18.6

Brady 10/25/2016 403 486 41.4 20.6 29.1 20.4 39.4 27.3 23.3

Abilene 10/27/2016 552 707 46.6 45.5 39.7 32.8 39.5 43.9 35.7

TAM 114 and SY Grit appear to require greater vernalization (~500 hours)

Note that low vernalization requirements generally align with earlier maturity and greater potential risk of frost injury after jointing

Varieties should not be selected based on vernalization requirements alone.

Rather, it is helpful to know the vernalization requirement of the varieties you have planted so that issues can be forecasted in the event of a warm winter.

Variety selection

Depending on how fast you can identify a potential vernalization issue, there is opportunity to:

◉ Avoid potential wasted top-dress fertilizer.

◉ Terminate and get ready for a summer crop.

◉ Graze out (goat prices are good).

Management Implications

Species and Variety Selection

Project reports: Forage variety trial

varietytesting.tamu.edu

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Forage Yield Distribution

TAMbar 501 TAM 114 Trical 348

When do you need the forage?

Grazing & Grain 2019 project assessed seeding rate and cutting height

Dual-use Wheat

Cutting Height vs. Forage Yield

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Cutting Height vs. Grain Yield

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Impact of cutting height on forage nutritive value

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RFV

Seeding rate effects on NDF, and RFV

Seeding Rate (million ha-1) NDF (%) RFV

1.5 43.3 b 148.5 a2.2 44.0 ab 144.4 b3.0 44.4 a 142.6 b3.7 44.7 a 143.6 b

Dual-use management and variety trials underway - 2020

Testing warm- and cool-season legume forage and cover crops in wheat-cotton rotations.

Cover Crop Trials – Mereta, TX

Red Clover

Crimson Clover

Hairy Vetch

Silver River Sweetclover

Winter peas

Pea Nodules

Active N-fixing!

Questions?

Reagan Noland Twitter: @WTXAgronomy Email: reagan.noland@ag.tamu.edu