Plant propagation 61 plant layering 60 plant harvesting 59 Sociology 39 Engineering 38 Genetics 38 atmosphere 38 Climatology 33 metabolism 25 Plant cell 23 Management 22 Chromosomes 21 Plant physiology 20 Cytology 19 Economics 19 morphology 17 Crop improvement 16 Cell Division 15 Metabolism 15 Currency 14 Morphology 14 Photosynthesis 14 Taxation 14 Trade Union 14 Wage Act 14 photosynthesis 14 Biochemistry 13 Expenditure 13 Microbiology 13 Nucleus 13