The correct option is (a).
Explanation
Post-harvest losses in agricultural produce, particularly grains, occur due to various environmental and biological factors during storage. These factors are broadly classified into biotic (living) and abiotic (non-living) categories, which degrade the quality, weight, and germinability of the produce.
Statement-wise Analysis:
- Statement 1 is Correct: Biotic factors refer to living organisms that cause damage to stored grains. These include insects, rodents (such as rats), birds, mites, fungi, and bacteria. These organisms consume the grains or cause spoilage through contamination and metabolic activities.
- Statement 2 is Incorrect: Abiotic factors are non-living environmental conditions. While inappropriate temperature is a significant factor, it is not the only one. Moisture content (humidity) is a critical abiotic factor. High moisture promotes fungal growth and enzymatic activity, leading to spoilage. Therefore, abiotic factors include both inappropriate moisture and temperature.
- Statement 3 is Incorrect: Storage losses are not limited to quantity (weight loss). They also encompass qualitative degradation. Discolouration of produce indicates chemical changes or microbial attack, leading to poor marketability and loss of nutritional value. Consequently, discolouration is explicitly considered a form of storage loss.
Key Takeaway:
Storage losses in grains are caused by a combination of biotic factors (insects, rodents, fungi, bacteria) and abiotic factors (primarily inappropriate moisture and temperature). These result in degradation of quality, discolouration, loss of germinability, and weight loss.