Cereals are those crop which provide the edible seeds like rice, wheat , lentil is considered as cereals. These cereals are the rich source of carbohydrates, provide many minerals, and also provide protein and as a rich source of vitamins. Hence, for the better utilization of all of these, the human body required a food in a proper dose. As with the passage of time, the population is increasing day by day, food is required more and hence yield of a crop is required in higher amount. The yield of a crop can be basically depends upon many factors that may be endogenous factors or exogenous factors. These factors are not same for all crops but variation exists. A crop yield will be higher when its harvest index will be higher. Harvest index is the major factor which affects the crop production.
There are some major factors which almost effect on the production of all crops that are:
- It is usually known as the measurement of yield of a crop.
- It is the ratio of the total grain production of a crop to its biomass. Usually the biomass of above ground is taken instead of below ground biomass, because the below ground biomass also includes the roots and the process of taken the root biomass is difficult and during experiment, chances of error increases.
- Harvest index helps to measure the difference between the potential and actual yield.
- It is the ratio between grain yield and plant yield.
- For each crop, it acts as an efficiency indicator. And it is different for each crop.
- Harvest index is influenced by hereditary material as well as different environmental factors.
Harvest index for different crops:
For each crop, harvest index vary and for production of a crop per hectare on international basis, the value of H.I is fixed. Mostly, modern cultivars have 0.45-0.6 range of harvest index. But usually, harvest index vary from crop to crop. For example:
- Wheat have H.I about 4-0.5
- Maize have H.I about 4-0.5
- Sunflower have H.I approximately 3-0.4
- The harvest index of beans vary from 45-0.55
- lentils(masoor) have H.I about 45-0.55
- sorghum (charri)have H.I about 4-0.6
Why crops have low harvest index :
There are some factors which causes the low harvest index and ultimately lead to the low production of a crop.
- Use of non-specific variety for a specific area
- Distribution of seed rate
- Use of unapproved seed
- Late sowing of seeds
- Imperfect sowing method
- Plant population
- Attack of different type of diseases on different crops
- Attack of insects pest (sometimes may be host specific)
- Problem of weeds
- Decrease in plant protection
- Inappropriate fertilizer dose
- Non-availability of irrigation water
Harvest index contain different genetic traits and variability exists in these traits. Environmental factors also influences the harvest index and ultimately yield of a crop. Thus, it can be used as selection criterion for the productivity of a crop.
Written by: Khadija Tehseen Arshad
University of Agriculture, Faisalabad.