Effect of NPK , Biofertilizers and Plant Spacings on Growth and Yield of African Marigold ( Tagetes erecta Linn . )

African marigold (Tagetes erecta L.) belongs to family Asteraceae is a very popular commercial flower crop as loose flower in India because of its wider adaptability to various soils and climatic conditions, easy cultivation, profuse flowering habit, short duration to produce marketable flowers and good keeping quality. It is an established fact that nutrition plays an important role in the improvement of growth and yield of marigold. Nutrients directly affect the vegetative growth and yield of crop. Adequate supply of nutrients especially N, P and K are often considered important for realizing the maximum yield of any crop. Nitrogen is the chief constituent of several important elements like protein, nucleic acid and amino acids occurring in the plants. An adequate supply of nitrogen is associated with higher photosynthetic activity, vigorous vegetative growth, dark green color and carbohydrate utilization. It is unequivocal that nitrogen is an essential element required by all the plants, however it is found to be deficient in most of the Indian soils (Arakeri et al., 1956) [1] especially in soils of Rajasthan. Phosphorus is also a major nutrient required by the crops. It is indispensable constituent of nucleic acid, phospholipids and several enzymes. The most essential function of phosphorus in a plant is energy storage and transfer for proper metabolism. Potassium is not a constituent of any plant tissue or compounds but it is involved in the synthesis of amino acids. It imparts vigor and disease resistance to plants. It also regulates water loss from the plant by maintaining the balance between anabolism, respiration and transpiration. Biofertilizers play an important role in increasing availability of nutrients and productivity in sustainable manner. Azotobacter is a free-living bacterium which may add 25-30 kg nitrogen/ha/year in a field of non-legume crop under favorable conditions and also secrets some growth promoting substances. Spacing plays an important role for manipulating plant growth, flowering behavior and seed yield. Inter row and intra row spacing and balanced supply of nutrients are important for obtaining higher yield of good quality seeds (Sunitha et al., 2007) [2]. Therefore, the present study was undertaken with the objectives; to find out the optimum spacing between plants and to see the effect of NPK and biofertilizers on growth and yield of African marigold. Abstract A field experiment was conducted during winter season of 2014-15 to study the effect of NPK, biofertilizers and plant spacings on growth and yield of African marigold. Application of 100% RDF of NPK + Azotobacter + PSB gave significantly higher values of plant height (82.75 cm), number of primary branches per plant (16.18 cm), plant spread of 68.54 cm in EW direction to 62.22 cm in N-S direction, duration of flowering (68.01 days), chlorophyll content in leaves (2.56 mg/g), flower yield (184.13 q/ha) and took minimum days to appearance of first flower (54.11),. The spacing registered significantly linear reduction in plant height from closest spacing at 45 x 45 cm (78.55 cm), appearance of first flower (60.51 days), duration of flowering (58.51 days) and maximum primary branches per plant (16.55). Maximum plant spread E-W (60.15 cm) and N-S (56.85 cm), chlorophyll content in leaves (2.55 mg/g) and maximum flower yield ha (126.73 q) were observed in wider spacing i.e. 60×60 cm followed by 60×45 cm.