source of food

source of food

1. crops

   • can be protected by
     • biological control
       • chemical control
         • pestcides
         • herbicides
       • enviromental friendly
       • natural method e.g introduce predators
       • imbalance of eco system
   • need
     • sunlight
     • water
       • required for
         • growth
           • regulated for
             • plant hormones
     • air

2. improving plants and animals varieties

   • intensive production methods