AGR3301 Crop Physiology: Duckweed Growth Analysis Lab Guide

https://www.youtube.com/watch?v=vV9NjHA5uOg

Original video: https://youtu.be/vV9NjHA5uOg

Welcome to the essential video guide for the AGR3301 Crop Physiology Experiment. In this lab, we shift our focus from traditional land plants to duckweed, a "super-crop" capable of doubling its biomass in as little as 16 to 48 hours. This video will walk you through the entire experimental process, from the initial setup to final data analysis.

Phase 1: Materials collection (Day 0)

At the Laboratory:

1. Go to the Physiology Lab (Block D, Faculty of Agriculture) to collect your materials.

2. Collect the following items:

• 8 clear plastic cups

• 6 paper cups

• Duckweed

• Nutrient solution

• Wooden stick

• Red coloured paper

• Tray

3. Each group will be assigned ONE treatment:

• Blood Meal

• Feather Meal

• Urea

• CIRP

• White Sugar

• Melaka Palm Sugar

4. Collect duckweed samples:

• Fill up quarter of the plastic cup with water

• Take 2-3 scopes using the wooden sticks

• Cover the cup with parafilm

• Avoid damaged or white leaves

Phase 2: Home Care and Daily Monitoring (Day 1 – Day 10)

At Home:

1. Place your tray in a bright area. (Avoid direct midday sunlight (too hot))

2. Prepare the cups:

• Place each plastic cup inside a paper cup

• This reduces light and prevents algae growth

3. Add nutrient solution: Fill each cup to the 150 mL mark (~top line)

4. Inoculation: Place 3 healthy and similar size duckweed fronds into the cup.

5. Label your cups clearly:

👉 You have 6 cups total:

Day 5 harvest (T1):

• R1-T1

• R2-T1

• R3-T1

Day 10 harvest (T2):

• R1-T2

• R2-T2

• R3-T2

6. Maintenance: Top up evaporated water every 2 to 3 days to the top mark using the premixed nutrient solution.

7. Daily Data Logging: Perform the following two measurements every day at approximately the same time (e.g., 12:00 PM):

8. Light Measurement (GPS Status App)

• Download the Apps from the App store: https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&hl=en

• Open the GPS Status & Toolbox app.

• Use the light sensor (usually near the front camera) to measure the light intensity at the level of your plants.

• Record the value in Lux.

9. Aerial Imaging (Easy Leaf Area App)

You must take a daily aerial image to calculate the Leaf Area Index (LAI) and Crop Growth Rate (CGR).

• Download the apps here: https://play.google.com/store/apps/details?id=com.heaslon.EasyLeafArea

• Setup: Place a 4 cm² red scale square (2cm x 2cm) on the rim of the cup, ensuring it is at the same height as the duckweed.

• Capture: Open the Easy Leaf Area app and position the camera parallel to the water surface.

• Calibration:

• Move the Green Sliders until only the duckweed is highlighted.

• Move the Red Sliders until only the red scale square is highlighted.

• Record the leaf area value.

• Use the phone camera, take the one aerial image and save your image using the format: Treatment-Day-Replication (e.g., BloodMeal-R1-T1).

• Upload: Upload the daily images to the dedicated file link provided in the class chat.

Phase 3: Harvest and Analysis (Day 5 and Day 10)

At Laboratory:

Time 1 (T1) - Day 5

1. Bring 3 cups T1 (R1, R2, R3) back to the lab for destructive sampling.

2. Make sure to measure the leaf area using Easy Leaf Area app first

3. Fresh Weight: Strain the duckweed, pat dry with tissue for 30 seconds, and weigh on an analytical balance.

4. Dry Weight: Place samples in an oven at 60°C for 24 hours. Record the weight once dried.

Time 2 (T2) - Day 10

1. Bring the remaining 3 cups (R4, R5, R6) back to the lab.

2. Repeat the Leaf Area, Fresh Weight and Dry Weight measurements as done on Day 5

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