Basagran is a widely used selective herbicide in agricultural settings. Its active ingredient is bentazon, often found at 44.0% concentration. It controls certain broadleaf weeds and sedges. It works through contact action, affecting weeds it directly touches and providing control within 7-14 days.
Understanding Photosynthesis
Photosynthesis is the process by which plants convert light energy into chemical energy, forming sugars for growth. It occurs within chloroplasts, abundant in plant leaves. Chlorophyll, a green pigment within chloroplasts, absorbs light energy.
Photosynthesis unfolds in two stages: the light-dependent reactions and the light-independent reactions, or the Calvin cycle. The light-dependent reactions occur in the thylakoid membranes of chloroplasts. Light energy is captured by chlorophyll and converted into ATP and NADPH.
Photosystems, complexes of pigments and proteins in the thylakoid membrane, are involved in light-dependent reactions. Photosystem II (PSII) is the initial step where light energy is absorbed, exciting electrons. These electrons move through an electron transport chain, generating ATP and NADPH. Water splitting supplies electrons for PSII, releasing oxygen. The ATP and NADPH then power the light-independent reactions in the stroma, synthesizing sugars from carbon dioxide.
How Basagran Disrupts Photosynthesis
Basagran’s active ingredient, bentazon, functions as a Photosystem II (PSII) inhibitor, interfering with photosynthesis. Bentazon binds to the Qʙ-binding site on the D1 protein within PSII, located in the thylakoid membrane. This blocks the electron transport chain.
This blockage prevents the flow of electrons needed to convert light energy into ATP and NADPH. Absorbed light energy cannot be utilized, leading to excited chlorophyll accumulation. These excited chlorophyll molecules react with oxygen to form damaging reactive oxygen species (ROS), such as singlet oxygen and hydrogen peroxide.
Excessive ROS production causes oxidative stress in plant cells. This damages cellular components, including proteins, lipids, and photosynthetic cell membranes. Cell membrane integrity is compromised, leading to destruction. This widespread damage halts energy production, impairing physiological functions and leading to cell death in susceptible weeds.
Visible Effects on Plants and Practical Application
Plants affected by Basagran exhibit symptoms resulting from the herbicide’s action. The initial symptom is chlorosis, or leaf yellowing, especially in sun-exposed areas. This yellowing occurs because inhibited photosynthesis prevents chlorophyll production.
As damage progresses, chlorosis is followed by necrosis, the browning and death of plant tissue. This tissue death results from oxidative damage caused by accumulated reactive oxygen species due to the blocked electron transport chain. Compromised cell membranes and proteins lead to cellular function collapse, appearing as dead, discolored patches on leaves.
Basagran is effective as a selective herbicide due to its differential impact on weeds versus crops. Susceptible weeds cannot detoxify bentazon, leading to their demise. However, many crops like soybeans, corn, rice, peanuts, and peas can quickly metabolize bentazon. This rapid metabolism renders the herbicide harmless, allowing crops to outgrow any initial leaf speckling or bronzing. This selective action makes Basagran a valuable agricultural tool for controlling broadleaf weeds without harming cultivated crops, optimizing yield and health.