Forage Sorghum Growth Cycle – Timeline & Tips

Have you ever watched the tall, proud sorghum fields waving in the breeze? Sorghum is important to many and thrives even in dry areas. Ever wondered how forage sorghum grows?

Let’s step into the world of forage sorghum and look at its growth stages. From the beginning in the soil to full maturity, we’ll share tips to help you get the best yield.

Key Takeaways:

• Forage sorghum undergoes 10 official stages of growth and development, from emergence to physiological maturity¹.
• Counting leaves is an effective method to determine the plant’s stage, with approximately five fully expanded leaves before lower leaves start falling off¹.
• The boot stage typically occurs between 50 to 60 days after emergence, heralding the beginning of a crucial phase in the sorghum’s journey¹².
• Transitioning from the boot stage to the heading stage takes about 3 to 5 days¹.
• Flowering, a critical stage in the sorghum’s development, sees the progression of the panicle’s blooming from top to bottom, usually spanning 4 to 9 days¹.
• Sorghum panicles showcase remarkable diversity, ranging from tight and compacted to spreading with long branches¹.

Stage 5: Boot

In the growth cycle of forage sorghum, the boot stage is a key point. At this time, the sorghum’s panicle, or head, is tucked inside the flag leaf sheath, looking swollen. Leaf collars show up clearly, and the panicle is pushed up by a part of the stalk called the peduncle. Stress and the type of sorghum can affect how long the peduncle gets. The boot stage usually happens about 50 to 60 days after the plants come out of the ground³.

When the boot stage hits, the forage sorghum panicle begins to form, leading to the plant’s reproductive phase. This period excites both farmers and scientists as it prepares for the sorghum panicle to develop grains³. As the plant grows, it moves through various stages. Understanding these stages and how to manage them is crucial for the plant’s best growth.

About the Sorghum Panicle

The sorghum panicle, or head, is vital for the plant’s ability to reproduce. It makes the grain and affects the plant’s total yield and grain quality. The panicle has many florets, each with the potential to become a seed. Watching its growth during the boot stage and later stages is important for predicting the crop’s yield and quality³.

While in the boot stage, the sorghum panicle is kept safe inside the flag leaf sheath. But as the plant keeps growing, the panicle becomes easier to see and continues to grow. Managing this stage well, by providing the right nutrients and care, can boost the panicle’s size and the amount of grain it produces³.

Recommended Practices

To do well in the boot stage and later, it’s important to plant the sorghum correctly. The seeding rate depends on what kind of forage sorghum you’re growing. For regular forage sorghum, 12–15 pounds per acre is a good amount. Sudangrass needs about 20 to 30 pounds per acre, and sorghum-sudangrass hybrids do best with 20–30 pounds per acre if drilled, or 30–40 pounds per acre if spread out wide³.

By sticking to these planting tips, farmers can help their forage sorghum plants grow strong from the start. This makes sure the boot stage, and the development of the sorghum panicle, lays a strong base for the plant’s growth and how much grain it will give³.

Stage 6: Flowering

The flowering stage is key in the growth of forage sorghum. It starts at the top of the sorghum panicle and moves down. As the plant blooms, the panicle peduncle grows longer. This process usually takes 4 to 9 days for each panicle.

Hybrid maturity is judged by how quickly a sorghum plant reaches this stage. When over half of the plants are blooming, the crop is in half bloom. Flowering is a major step in sorghum’s life cycle, important for making seeds.

The sorghum’s panicle holds the flowers which turn into grain. This vital stage leads to grain production. It also lays the groundwork for later growth stages.

Based on data from⁴, harvesting hybrid sorghum in the vegetative stage can yield 7.26 to 7.40 dry tons/acre. These figures outperform yields from later stages, showing the vegetative stage’s importance.

Flowering is a critical phase where sorghum plants reproduce and start grain production. Careful monitoring during this stage is necessary to boost yields and ensure successful development.

Yield stability for hybrid sorghum can change based on the year and weather conditions. In Florida, good years can see yields over 11.67 tons/acre. However, bad years might only produce 2.55 to 7.27 tons/acre, says⁴.

Planting time affects yields too, notes⁴. Spring-planted sorghum often yields over 8 dry tons/acre. Yet, planting in summer usually results in lesser yields.

In 2009, Florida’s hybrid sorghum showed strong structure with less than 1% lodging, according to⁴. This suggests a very stable plant build.

Seed treatments mentioned in⁴ include Concep III®, Cruiser®, and Gaucho® for pest control, plus fungicides like thiram. These treatments help protect seeds, ensuring better growth and yield stability.

Stage 7: Grain Filling

The grain filling stage is key in forage sorghum’s growth. During this time, the plant works on developing and filling the grain more. The kernel quickly fills up with starch, making the grain heavier. About half of the grain’s final weight is reached at this stage⁵.

As this phase moves forward, some older leaves might begin to die. This is more common if there’s not enough water, due to drought. Yet, if plants get enough water, less leaves will die. This helps the grain fill better⁶⁵.

This phase is vital for the quality and amount of sorghum a farmer gets. So, knowing what affects grain filling is important for a good harvest. But, how sorghum grows during this time can change depending on the place and the year⁶. Farmers should look at many kinds of information to understand what’s best for their crops⁶.

Let’s look at why the grain filling stage is so important. Medium-maturity sorghum usually spends 32 to 35 days in this phase⁵. The number of seeds is very important here. It’s responsible for about 70% of the grain yield⁵.

About 30 to 35 days after the plant comes up, sorghum starts working on panicle initiation. Any problem here can result in fewer seeds. This lowers the grain yield⁵. Good weather and the right number of plants can lead to more tillers and seeds⁵.

In summary, the grain filling stage is very important for sorghum. It’s when the grain really starts to fill out and store starch. To get a good harvest, farmers need to watch this stage closely⁶⁵.

Stage 8: Hard Dough

In the growth stages of forage sorghum, the hard dough stage stands out. This phase signifies the near end of grain growth. Seeds toughen and change color, showing they’re almost ready⁷.

It’s crucial to remember that lack of water after flowering can cause problems. These include weak plants and poor-quality grain⁷.

Forage sorghum changes nutritionally during the hard dough stage. This phase boosts the crop’s dry matter and starch. But it also reduces the protein and fiber, affecting how digestible it is⁷.

Harvesting forage sorghum at the soft dough stage could be great for feeding dairy cows. It offers stable energy for milk⁷.

A Nebraska study showed cows eating BMR sorghum produced as much milk as those eating corn silage. But when sorghum partially replaced corn silage at the milk stage, cows gave more milk fat despite eating less⁷.

Older BMR sorghum varieties didn’t yield as much as conventional ones. Yet, newer BMR types now match those yields thanks to breeding improvements⁷.

Stage 9: Physiological Maturity

Physiological maturity marks a key stage in forage sorghum’s life. It’s when the plant is at its heaviest dry weight. The grain is also fully mature by then.

Detailed Notes: This maturity happens as a black layer forms at the seed’s base. Grain moisture can be from 25% to 40%, affected by growth conditions. It takes about 40 to 45 days after flowering to reach this stage.

Understanding Physiological Maturity

The forage sorghum goes through big changes during this time. Grain sorghum hits its max dry weight. It usually has about 25-35% moisture.

⁸ Sorghum grows through ten stages, with stage 9 being physiological maturity. This point shows the grain is fully grown and ready to be harvested.

At this point, the grain gets hard and dry. A black layer at the seed’s base tells us it’s mature.

It’s vital to check the grain’s moisture to pick the best harvest time. Harvesting at the correct moisture level prevents loss and keeps the grain quality high.

Growth conditions and sorghum types can change how long maturity takes. But generally, it’s 40 to 45 days from flowering to this important stage.

Sorghum growers must watch the crop’s progress to pick the best harvest time. They look at moisture and the plant’s health.

Maintaining Yield Potential

Reaching physiological maturity is key to getting the most yield from forage sorghum. It means the grain’s development is complete, and it’s at its largest weight.

⁸ Yield factors like head count, seeds per head, and seed size and weight all play a role in overall yield⁸.

Evaluating the plant’s health and nutrient intake is critical now. This helps ensure the plant can reach its highest yield potential.

Studies have shown keeping the right nutrition levels up during the growth cycle, including physiological maturity, can greatly affect yield. Adequate nutrition boosts grain quality and total crop productivity.

Nutrient Requirements at Different Growth Stages

Knowing how forage sorghum needs different nutrients at each growth stage is key to getting the most yield. As the plant grows, what nutrients it needs changes. We’re going to look into what nutrients forage sorghum needs from planting to harvest.

Stage 2: Seedling

A young forage sorghum plant works hard to grow strong roots. Phosphorus (P) and potassium (K) are really important for this. Having enough of these nutrients early on helps the plant grow well right from the start⁹.

Stage 3: Vegetative Growth

When the plant starts to grow leaves and stems, it needs more nutrients. Nitrogen (N), phosphorus (P), and potassium (K) are key for this growth. About 7 pounds of nitrogen for each ton of yield is what sorghum takes from the soil. Around 100-150 pounds of nitrogen is needed during its life⁹. Phosphorus and potassium needs are about the same as for corn silage⁹.

Stage 4: Pre-Boot

At the pre-boot stage, the plant gets ready to make flowers. It still needs lots of phosphorus (P) and potassium (K) for good flower and seed growth. Making sure these nutrients are available helps the plant fill its grains well and gives a good yield⁹.

Stage 5: Boot

During the boot stage, the sorghum is getting ready to flower. It’s important to have enough nitrogen (N) for strong stems and leaves. Thinner stems from planting more seeds closely can mean animals don’t dislike the stems as much when eating. Plant about 30,000 seeds per kg depending on the type of sorghum¹⁰

Stage 6: Flowering

The plant focuses on making flowers at this stage. Getting plenty of nitrogen (N), phosphorus (P), and potassium (K) is key now. Nova and others found in 2021 that some hybrids can grow pretty tall and are good for grain, silage, or as an alternative to maize¹⁰.

Stage 7: Grain Filling

When it’s time for grain filling, the plant really starts to use up nutrients. Nitrogen (N), phosphorus (P), and potassium (K) are crucial for making healthy seeds. Not having enough of these can lower the grain yield and affect the crop’s success⁹.

Stage 8: Hard Dough

At the hard dough stage, the plant doesn’t need as many nutrients. Some maintenance fertilization might be needed, though. Now, the focus is on getting the seeds to mature well. Good management is key to quality seeds¹¹.

Stage 9: Physiological Maturity

When forage sorghum is fully grown, keeping up with nutrients is still important. This helps with the last bit of seed development. Using nitrogen (N) wisely can help the next crop grow well too⁹.

It’s really important to understand what nutrients the plant needs at each stage. Giving the right nutrients at the right time helps forage sorghum crops grow better. This means more productivity for farmers.

To learn more about controlling weeds in sorghum, the Penn State Agronomy Guide is a great resource. It has a lot of advice on what herbicides work best⁹.

Growing Degree Units and Sorghum Growth Stages

Growing Degree Units (GDUs) are key in understanding when sorghum will grow through its stages and mature. By using temperature data to figure out GDUs, farmers can make smarter choices about their crops.

Temperature greatly affects how sorghum grows. For seeds to sprout, the soil must be at least 60°F, but 65°F is better¹². Knowing the right temperatures helps farmers ensure the crops start off strong.

Different sorghum types need varying growth days. Forage sorghums need about 90 days. Sorghum-sudan and sudangrass varieties need around 40 good days for each cut¹². These time frames help farmers plan for the growth and development of their crops.

Harvest times for sorghum-sudan and sudangrass are different too. In warm weather, they’re ready for a first cut in 45 to 60 days. A second cut happens in 30 to 40 days¹². This info helps with planning when to harvest.

Sorghum silage has an ideal moisture range from the high 60s to low 70s. Cutting it at a 1-inch size when moisture is at 72 percent prevents too much juice¹². Managing moisture is key to storing quality silage.

Sorghum plants have unique traits useful for managing crops. Brachytic dwarf plants are shorter due to closer nodes. They produce a bit less but don’t lose much yield¹². Their sturdy nature lessens damage risk.

Photo-period sensitive sorghums start heading after getting about 12 hours and 20 minutes of sunlight daily. This offers a longer harvest period, adding flexibility for farmers¹².

High-quality forage is essential. Sorghums with the brown mid-rib (BMR) trait have lower lignin and better fiber digestibility. This leads to improved livestock nutrition¹².

In some situations, preventing grain in sorghum is needed. Male sterile plants work well for markets that don’t feed grains to livestock. They stop grain production without outside pollen¹².

Growing Degree Days (GDDs) monitor growth in crops like sorghum. Each crop has its own base temperature for growth¹³. Sorghum, field corn, sweet corn, and soybeans use 50°F. Alfalfa uses 41°F, as it’s suited for cooler climates¹³.

To calculate GDDs, subtract the base temperature from the average daily temperature. If GDDs are positive, it means the crop is growing well above its base temperature¹³. This helps predict growth more accurately than just using a calendar.

Tools like the Cornell Climate Smart Farming Growing Degree Calculator aid farmers. They can anticipate crop stages and inse

ct and weed lifecycles¹³. This makes crop management decisions more informed.

Conclusion

Getting to know the forage sorghum growth cycle is key to getting the best yields. Farmers need to watch how the plants grow. They also need to choose the right hybrids, use the right amount of fertilizer, and water the plants well.

Information¹⁴ from countries like Venezuela, Australia, Brazil, Egypt, Pakistan, and the USA shows us how important forage sorghum is. It helps with milk production in cows, weight gain in steers, meets the nutrient needs of sheep, and manages weight in cattle. This shows that forage sorghum is a great choice for animal feed all across the world.

Furthermore, studies¹⁵ outline the growth stages of forage sorghum, like emergence, flowering, and grain filling. Each stage is important for the crop’s growth and how much yield it will give. Good management, like ensuring the plants have enough nutrients and keeping an eye out for pests, is crucial.

Last but not least, data¹⁶ on sorghum-sudangrass hybrids show their strengths. They can grow a lot of biomass, keep weeds down, fight off diseases, improve the soil, and handle different soil pH levels and dry conditions. These hybrids offer great benefits when used as cover crops or forage.

Source Links

1. https://www.sorghumcheckoff.com/our-farmers/grain-production/growth-and-development/ – Growth and Development – Sorghum Checkoff
2. https://www.cropscience.bayer.us/articles/bayer/sorghum-growth-stages – Sorghum Growth Stages | Crop Science US
3. https://extension.umaine.edu/publications/resource/bulletin-2271-maine-forage-facts-sorghum-sudangrass-and-sorghum-sudangrass/ – Maine Forage Facts: Sorghum, Sudangrass and Sorghum-Sudangrass
4. https://edis.ifas.ufl.edu/publication/AG343 – SS-AGR-333/AG343: Forage Sorghum
5. http://glasscock.agrilife.org/files/2015/05/Sorghum-Growth-and-Development.pdf – Sorghum Growth and Development
6. https://www.lewishybrids.com/en-us/agronomy-library/sorghum-growth-stages.html – Sorghum Growth Stages
7. https://www.journalofdairyscience.org/article/S0022-0302(19)30478-3/pdf – Optimal harvest timing for brown midrib forage sorghum yield, nutritive value, and ration performance
8. https://www.sorghumcheckoff.com/wp-content/uploads/2021/11/2018_04_17_MidAtlanticGuide_ea_New-Logo.pdf – PDF
9. https://extension.psu.edu/planting-forage-sorghum-sudangrass-and-sorghum-sudangrass-hybrids – Planting Forage Sorghum, Sudangrass, and Sorghum-Sudangrass Hybrids
10. https://epgseeds.com.au/2022/09/09/forage-sorghum-planting-grazing-guide/ – Forage sorghum planting and grazing guide | EPG Seeds
11. https://extension.psu.edu/sweet-sorghum-production-basics – Sweet Sorghum Production Basics
12. https://www.agproud.com/articles/32880-sorghum-sorghum-sudan-or-sudangrass-which-is-right-for-me?xid=nl_Emailscontent – Sorghum, sorghum-sudan or sudangrass: Which is right for me?
13. https://extension.psu.edu/understanding-growing-degree-days – Understanding Growing Degree Days
14. https://www.feedipedia.org/node/379 – Sorghum forage | Feedipedia
15. https://www.sorghumcheckoff.com/wp-content/uploads/2021/11/westforageguideforweb092611.pdf – PDF
16. https://www.sare.org/publications/managing-cover-crops-profitably/nonlegume-cover-crops/sorghum-sudangrass/ – Sorghum Sudangrass Cover Crop – SARE