|Regenerative Agriculture Technologies for the Hill Farmers of Nepal: An Information Kit (IIRR, 1992, 210 p.)|
|Cropping systems and post-harvest technologies|
Plant stand is an important yield component of maize because yield per unit area is the product of yield/plant and number of plants/unit area. To obtain maximum yield, an optimum plant population and planting arrangement are necessary. In the traditional system of maize cultivation, farmers plant maize behind the plough without using exact plant spacing. They use a high seed rate (3040 kg/ha) for security against emergence-insect-wind-hail- and drought-damage and to provide fodder for their livestock. Generally, plant stand at emergence is as high as 75,000 plants/ha. Farmers gradually thin out the plants between first and second weeding and the resultant stand at harvest is usually 30,00045,000 plants/ha. Experiments done at Lumle found that farmers' timing and practice of thinning produced about 10% lower maize yield as compared-to thinning at 30 days after planting. Therefore, maintenance of recommended plant stand is a problem in maize production in Nepal, especially in the hills.
The following recommendations are made in order to maintain proper plant stand of maize and thereby improve the production as well as to help meet the fodder needs of the farm.
· Optimum plant stand under midhill conditions is about 50,000 plants/ha (2,500 plants/ropani). This population will yield the highest grain crop under relatively fertile conditions. Planting 25 kg seed/ha at a spacing of 75 cm × 25cm will give this plant population with a small allowance for - poor emergence. Behind-the-plough planting of this amount of seed yields as high as line planting. Proper spacing can be maintained through proper thinning before competition starts. (i.e., no more than 30 days after planting). Delayed thinning increases plant competition and reduces grain yields. Maintaining 5 plants/sq m after thinning gives optimum yield.
· If fodder is a desired product from maize, field-seeding rates can be ad justed upward. High plant population will still result in high-grain yields as long as the maize plant population has been reduced to the recommended 50,000 plant/ha by no more than 3() days after planting. The thinned plants are fed as fodder.
· Plant stand/unit area varies from farm to farm, variety to variety, location to location, and according to cropping patterns. Genotypes with less leaf area/plant require more plants/unit area; shorter plants require narrower rows than taller varieties. Plant stand should be higher under high fertility conditions and slightly lower stands are to be maintained on soils with low fertility and in intercropping systems (e.g., Maize/Millet, Maize+Soybean and Maize+Potatoes).
Proper plant spacing - Behind the plough sowing followed by thinning at 30 days after sowing yields as well as 75cm × 25cm spacing.
Three additional practices will help to maintain optimum plant population and high yields.
· Under poor stand of maize, gap filling within two weeks reduces yield loss.
· Earthing-up protects plants from wind, break and root lodging.
· Under low-fertility conditions associated with high-density planting, barrenness is a problem in maize production; random detasseling of 50% tassels before pollen shedding reduces barrenness significantly and improves yield. Detasseling should be done as soon as the tassel appears in the whorl. Flag leaf should not be removed while detasseling. Young tassels are very rich in protein and are good for fodder.
Gap filling - hilling up