Force of Detachment in Citrus Leaves: Karthik's Scenario

[karthikjoseph]

Hi,

I am a Horticulture grad student and I have a scenario which could be explained by concepts in physics. Since I have a little knowledge in physics, I hope to get some answers in this forum.

I have attached the picture of the citrus leaf for better understanding. There are two points where detachment can take place (AZ1 and AZ2). I sprayed with a chemical to loosen the tissues at these points and when I measured the detachment force, the reduction in detachment force was same at both these points. But still the leaf blade falls off first at AZ2 and only after few hours, the petiole drops at AZ1. I thought that it might be related to the weight of these tissues (leaf blade weighs about 600 mg and petiole weighs about 40 mg). But still if the two points loosen at the same time shouldn't the leaf blade and petiole detach together at AZ1 since the weight of leaf blade and petiole is heavier than the weight of leaf blade alone? It might be related to a simple concept, but any response will be very much appreciated.

Karthik.

 

[AndyW]

Hi Karthik,

It's great that you are looking for answers in this forum. I can help you understand this scenario using concepts in physics.

Firstly, the detachment force at AZ1 and AZ2 is reduced by the chemical you sprayed because it weakens the bonds between the cells at those points, making it easier for the leaf to detach. However, the weight of the tissues alone does not determine when detachment will occur.

The key concept to understand here is the center of mass. The center of mass is the point at which the mass of an object is evenly distributed. In this case, the center of mass of the leaf blade and petiole combined is closer to AZ2 due to the weight of the leaf blade. This means that when the tissues are loosened at both points, the center of mass shifts towards AZ2, causing the leaf blade to detach first.

Additionally, the petiole is attached to the stem at AZ1, providing some additional support and resistance to detachment. This is why it takes a few hours for the petiole to detach even after the tissues are loosened at AZ1.

I hope this explanation helps you understand the scenario better. Keep exploring and asking questions, that's what science is all about! Good luck with your studies.