The reproduction system in peanuts is very distinct as they do not reproduce as most nuts or legumes. Moreover, they flower above the ground and fruit under the soil. This distinctive feature of peanuts leads to confusion regarding their reproduction.
Peanuts reproduce through self-pollination. That means the plant doesn’t need outside aids like bees or flies to pollinate itself. Self-pollinating flowers of a peanut plant release a peg, which contains the ovary that buries itself in the soil as it falls and matures as a new peanut plant.
As you read further, we will dive deeper into understanding the peanut’s reproduction process in detail. Moreover, we will also see the differences between peanuts and other nuts.
The Process of Reproduction in Peanuts
Boote systematically arranged the reproduction process of peanuts in 1982. He categorized the whole plant growth into two stages; vegetative and reproductive stages. To solve our query about peanut reproduction, we will only look at the reproductive stage.
The reproductive stage is divided into nine steps. Let’s have a look at each stage and its process:
R1 – Beginning Bloom
Peanut plants start to bloom about 30 days after their first emergence. In this stage, the plant begins to produce flowers. The number of flowers increases until the plant reaches its peak of blooming at about 60 to 70 days after emergence.
After the blooming stage, the plant declines to produce more flowers and enters the next phase of the beginning peg. The peg rises at the back of the flower.
R2 – Beginning Peg
The gynophore is commonly known as a peg, which contains an ovary at the tip and grows downwards to push itself into the soil. After burying itself in the earth, the ovary begins to develop and takes up a horizontal position in the ground.
The peg generally takes about one to two weeks to reach the soil and penetrate the ground after pollination. It is sensitive to light, touch, and gravity, which makes it capable of transporting the newly fertilized ovules into the soil.
R3 – Beginning Pod
After entering the soil, the ovary starts to swell. The swollen ovary, which is the tip of the peg, is called a pod. The beginning stage of the pod does not take more than a couple of days to swell and enter the next phase of the full pod.
R4 – Full Pod
When only a single peg swells and takes shape, it is not yet considered a full pod. However, when about 50% of a plant’s pegs achieve the set of podding, that is called the full pod. Pods become countable, measurable, and weighable.
It may take about 60 to 70 days for a plant to reach this stage after planting. Depending on its variety and botanical type, the number of pods reaches its zenith between 80 and 120 days.
R5 – Beginning Seed
In the beginning seed stage, seeds begin to develop inside the pod. The stage denotes that 50% of the sample plants have at least one pod that has started growing the seed.
The seed cotyledon becomes visible in the beginning stage in the cross-section of the pod. The endocarp inside the woody shell recedes with the growth of the ovule and disappears entirely after seed maturation.
R6 – Full Seed
In this stage, the seed takes its shape. However, not all pods develop simultaneously in the same plant, depending on their pegging stage. If the pegging starts late, seeds will take time to mature respectively.
R7 – Beginning Maturity
After getting its shape, the seed starts to mature. The outer shell of the peanut hardens, and the endocarp (the innermost layer of the pericarp) continues receding until the seed gains its full size. The pod shows visible natural coloration of the pericarp.
R8 – Harvest Maturity
The seeds mature entirely and are ready to be harvested in this stage. In the harvest maturity, 66 – 75% of the pericarps show natural coloration and have developed testa. Seeds have passed all the stages of maturation. Hence, it is high time to harvest peanuts before their outer layer starts to disintegrate for the next crop cycle.
R9 – Over Mature Pod
The last stage includes the process of over maturation if not cultivated timely. In this stage, the woody shell of peanuts will start ripening and turn tan orange in color. These new peanuts will begin an unknown lifecycle near the mother plant and develop a colony if not harvested in the next crop cycle.
How Long Does The Peanut Reproductive Cycle Take?
A peanut plant takes about 120 – 150 days to mature depending on its variety, before it’s harvested. However, the period mentioned above includes both its vegetative stage and reproductive stage.
The peanut plant’s reproductive cycle takes 90 – 120 days.The first 30 days of a peanut plant’s life are spent in vegetative growth. The next three to four months are spent in the reproductive stage.
Here we will look at the timeline of a peanut plant’s reproductive stage.
- R1 – Beginning Bloom (30-31 days).
- R2 – Beginning Peg (39-42 days).
- R3 – Beginning Pod (46-51 days).
- R4 – Full Pod (52-60 days).
- R5 – Beginning Seed (57-62 days)
- R6 – Full Seed (67-74 days)
- R7 – Beginning Maturity (80-93 days)
- R8 – Harvest Maturity (119-129 days)
- R9 – Over Mature Pod (after 123 days)
Peanuts prefer a warm season for the growing cycle to proceed and the plant to mature properly. That is why it is best to start planting peanut seeds in mid to late spring to give it enough time to bloom and undergo the reproduction process in the summer and be ready for harvest by fall.
The ideal month to start growing peanuts varies significantly depending on the region because of varying climates. Different varieties of peanuts also have different lifespans as some can dry up in winter but regrow in spring.
Peanuts have a unique reproductive system. Although they come from the legumes family and count under the nut category, they are pretty different from both. Their reproductive process is different from true nuts and other legumes like peas or lentils.
The peanut plant is self-pollinating and flowers above the ground but bears fruits under the soil. Pegging is a unique feature in peanuts that works as a bridge between flower and earth.