🌱 How Plants Sense Time: Photoperiodism & Vernalisation Explained!

-

Preparing for NEET 2025 Botany? Here’s a concept that confuses many but is actually quite fun once you get it. Plants cannot walk, talk, or text, but they are master timekeepers. They can sense day length, seasons, and even cold weather to decide when to flower. This magical ability is explained through photoperiodism and vernalisation. Let’s dive in!


---

☀️ Photoperiodism: Plants and Day Length

Plants are not random about flowering. They flower only when the light conditions are just right. This response of plants to the relative length of day and night is called photoperiodism.

Short Day Plants (SDPs): Flower when nights are longer than a critical period. Example – Rice, Soybean, Chrysanthemum.

Long Day Plants (LDPs): Flower when nights are shorter than a critical period. Example – Wheat, Barley, Spinach.

Day-Neutral Plants: Flower irrespective of day length. Example – Tomato, Cotton, Cucumber.


👉 Exam Tip: Always remember it is the length of the night (dark period) that is critical, not the day.


---

❄️ Vernalisation: Plants and Cold Treatment

Some plants won’t flower unless they feel the chill of winter. This process of stimulating flowering by exposure to a period of low temperature is called vernalisation.

Seen in biennial plants like Carrot, Beet, Cabbage and winter varieties of Wheat and Barley.

It prevents premature flowering and ensures plants flower at the right season.

Vernalisation can be reversed by high temperature – called Devernalisation.


👉 NEET Hotspot: Vernalisation is an adaptive mechanism to synchronize flowering with favorable conditions.


---

🌾 Applications in Agriculture

Farmers can manipulate photoperiodism to grow crops in different seasons.

Vernalisation is used to increase yield in winter crops.

Hybridization programs depend on controlling flowering time.



---

📚 NEET Practice Questions

Q1. A short-day plant requires 14 hours of uninterrupted darkness. If exposed to 2 minutes of red light in between, will it flower?
👉 Answer: No, because red light interrupts the critical dark period.

Q2. Vernalisation is essential in:
a) Rice
b) Wheat (winter variety)
c) Cotton
d) Maize
👉 Answer: b) Wheat (winter variety)


---

📝 Quick Revision Notes

Photoperiodism = Response to day length.

Critical factor = Night length.

Vernalisation = Cold treatment for flowering.

Devernalisation = Reversal of vernalisation by heat.

NEET loves to test examples of SDP, LDP, and day-neutral plants.

Comments

Post a Comment

Popular posts from this blog

Celebrating Teacher’s Day 2025: Honoring the Architects of Knowledge

-
Image
The Origin of Teacher’s Day Teacher’s Day in India commemorates Dr. Sarvepalli Radhakrishnan, born on September 5, 1888. A philosopher, statesman, and the second President of India (1962–1967), Dr. Radhakrishnan believed education was the cornerstone of progress. When students and admirers suggested celebrating his birthday, he humbly proposed that the day be dedicated to honoring all teachers instead. Since 1962, September 5th has been celebrated as Teacher’s Day across the country, a tradition that continues to thrive. Why Teachers Matter Teachers are more than just educators—they are mentors, role models, and catalysts for change. On this Teacher’s Day, let’s reflect on their impact: Shaping Minds: They introduce students to new ideas, critical thinking, and problem-solving skills. Building Character: Beyond academics, teachers instill values like discipline, empathy, and resilience. Inspiring Futures: Many successful individuals credit a teacher for sparking...
Read more

NEET 2025 – Cell: The Unit of Life | NCERT-Based Notes + Diagrams

-
Image
Post Content: Introduction: "Cell: The Unit of Life" is a conceptual and factual chapter. NEET 2025 can include diagram-based MCQs and questions from cell organelles and types of cells. Focus on NCERT keywords and functions. 1. Discovery of Cell Discovered by Robert Hooke in 1665 (cork cell) Cell Theory by Schleiden & Schwann Rudolf Virchow: "Omnis cellula-e-cellula" – cells arise from pre-existing cells 2. Prokaryotic vs Eukaryotic Cells Feature Prokaryote (Bacteria) Eukaryote (Plants/Animals) Nucleus Absent Present Organelles No membrane-bound Membrane-bound Ribosome Type 70S 80S Cell Wall Peptidoglycan Cellulose (plants) 3. Cell Organelles Nucleus: Double membrane, contains nucleolus and chromatin Mitochondria: Powerhouse, double membrane, has its own DNA Plastids: Chloroplast: Green, photosynthesis, has DNA Endoplasmic Reticulum (ER): Rough ER: Protein synthesis Smooth ER: Lipid synthesis Golgi Apparatus: Modifies & packages proteins Lysosome...
Read more

🌱 Plant Kingdom – Bryophytes (Mosses & Liverworts) | NEET 2025 Notes

-
Image
Introduction Bryophytes are often called the “Amphibians of the Plant Kingdom” because they require water for reproduction but can survive on land as well. They form a crucial link between algae and pteridophytes. For NEET aspirants, bryophytes are an important NCERT-based topic that often appear in exams with direct questions. --- General Characteristics of Bryophytes Non-vascular plants (no xylem or phloem) Plant body is thalloid (undifferentiated into true root, stem, and leaves) Anchored by rhizoids instead of roots Reproduction occurs through spores Life cycle shows alternation of generations (gametophyte dominant, sporophyte dependent) --- Classification of Bryophytes Bryophytes are divided into three main groups: 1. Liverworts Example: Marchantia Plant body is dorsiventral, thalloid Asexual reproduction: by fragmentation and gemmae Sexual reproduction: male and female sex organs borne on separate structures 2. Mosses Example: Funaria, Polytrichum Gametophyte has two ...
Read more