Step 1: Planting systems overview.
Planting systems are chosen based on topography, slope, and soil conditions.
Step 2: Hillside planting.
On hilly terrains, planting across the slope (contour planting) is followed to reduce soil erosion and conserve moisture.
Step 3: Elimination of other systems.
- Square and rectangular systems are suitable for plain lands.
- Hexagonal system is also practiced on plains for maximum utilization of land.
- Only the contour system is suitable for hills.
Step 4: Conclusion.
Hence, on hills, the contour system is adopted.
Final Answer: \[ \boxed{\text{Fruit orchards on hills are planted using the Contour system.}} \]
Mandarin orange-Fruit Crop
Mandarin oranges (Botanical name - Citrus reticulata, Family - Rutaceae), commonly known as Santra, are the most refreshing and health-promoting juicy fruits. Besides Vitamin C, it is an excellent source of pectin and certain essential oils. The juice is advised to patients. Subtropical and tropical climates are required for the growth of santra. The trees grow luxuriantly in 1.5 m deep well-drained soils free from excess salts and having adequate content of organic matter. The important varieties are Nagpur santra (Maharashtra), Khansi mandarin (Assam), Coorg mandarin (Karnataka), Kinnow (Punjab), Emperor, Hill orange, Mudkhed seedless, and Honey (for kitchen gardening). Santra are commercially propagated by shield or ‘T’ budding on rootstocks like jamberi or rangpur lime. Average yield is 80 to 160 fruits per tree.