Yield Maximization

With the best management practices under less limited environment, it is possible to achieve the highest crop yield. Maximum yield achievable under a production system includes the best of all controllable factors needed to produce, the highest possible yield. The yield maximum generally varies with climate, soils and growing season. In a place where all the parameters are optimum during a perfect growing season, maximum yield should be approximate to the maximum potential yield. In this situation, all the production factors will be interrelated.
Growth of medicinal plants depends on solar energy, CO2, water and nutrients and solar energy is considered as the basis for determining productivity potential. If all the factors are non-limiting, the radiation use efficiency determines the photosynthetic rate, dry matter production and yield.

Maximum Economic Yield (MEY)

Maximum Economic Yield is the yield level where net profits are maximized in response to increasing use of inputs and management. Maximum Economic Yield is slightly lower than the maximum yield and is the point where the last increment of an input just pays for itself. Maximum Economic Yield also varies with the location, economic and soil conditions. This also represents the farmer's greater potential for economic survival. It is possible to get maximum net profit by selecting cost-effective inputs and management practices to produce MEY.
Each must be cost-effective when used singly but may provide the most profit from an interaction effect. The interaction should occur without limitations; changes in fertility and cultural practices play an important part. An integrated multiple production strategy should be worked out to achieve MEY. Choice of medicinal plant cultivars, timeliness of planting or sowing, treatment of seeds, maintenance of adequate plant population, amount and method of application of manures and fertilizers, optimum irrigation and appropriate plant protection measures are important to reap the maximum yield potential.

Plant Population and Crop Yield

It would be useful to know optimum or critical population densities to exclude population as limiting factor for crop yields.

Plant Population and Geometry
Plant population is defined as the number of plants per unit area. Geometry is the pattern of distribution of plants over the ground or the shape of the area available to the individual plants. When plants are widely spaced, dry matter production will at first tend to increase linearly with increase in plant density due to no or minimum competition between the adjoining plants. Further increase in density may reduce the dry matter production probably due to competition between plants and the yield of the individual plants may get reduced. However, this is compensated by the increase in the number of plants per unit area. Any further increase in plant density results in a plateau of practically constant dry matter production. This indicates that an equilibrium has been reached at which the increase in production due to increased plant number compensates the reduction in the production of the individual plants.

Optimum number of plants is required per unit area to utilize efficiently the available production factors such as water, nutrients, light and CO2. Maximum exploitation of these factors is achieved when the plant population puts forth maximum pressure on all the factors of production. As a result, individual plants are put under severe stress because of inter-plant competition. Normally maximum yields are obtained from plant population, which do not allow plants to achieve their individual maximum potential. Thus the entire community of plants is considered for higher production rather than the individual plant performance.

Response of Crop Plants to Plant Population

Modern varieties are much more responsive to closer plant spacing than traditional varieties. Though the yield per plant is lower at closer spacing, greater number of plants per ha compensates
the loss in yield of individual plants.

There is also negative effect of very high population density, particularly in branching crops. In soybean, there is elongation of internodes and plant height due to competition for sunlight under
dense situation, because of the etiolation.

Specific seasons: Crop seasons in India may be broadly grouped into three: kharif, rabi and zaid or summer seasons. The kharif ox South-west monsoon season is the important season in India. Crops are sown during June-July and harvested in September-October. All warm weather crops and crops having shorter-day length are grown during this season. The rabi or winter season crops are sown during October-November and harvested during February-March. Peninsular India gets North-East monsoon during this period. The crops requiring cold-dry weather and having longer day length are particularly cultivated during this season. Zaid or summer crops are grown during February-March to May-June. Since warm dry weather prevails during this season normally short-duration crop.