Introduction

Onion contributes 12.5% of total vegetable area and 10.3% of total vegetable production. In India, total area under onion cultivation is 1.064 million hectares with total production of about 15.118 MT. The Maharashtra state has maximum area of 4.15 lakh hectares and highest production of about 4.90 MT of onion in India(Anon., 2011). The growth and yield of cultivated crop plants are mainly influenced by two principle factors, viz., genetic and cultural or management factors. The first factor, deals with various plant breeding techniques for the improvement in crop varieties. The second factor, deals with supply of adequate nutrition, irrigation and plant protection etc.

The organic manure seems to act directly for increasing crop yield by accelerating the respiratory process through cell permeability or by hormones through growth action. It supplies nitrogen, phosphorus and sulphur in the available form to the plants through biological decomposition. Indirectly, it improves the physical properties of soil such as, bulk density, aggregation, aeration, permeability and water holding capacity (Chandramohan, 2002). The compost produced by using earthworms commonly called vermicompost is a rich source of macro and micro nutrients, vitamins, growth hormones etc.

The problem of high cost of chemical fertilizers and lack of availability of organics, integrated nutrient management such as organic matters like farmyard manure, vermicompost and biofertilizers use has become necessary. The information on role of farmyard manure, vermicompost and biofertilizers and their combinations on production of onion are very scanty. Therefore, there is an urgent need to study the influence of organic manures, chemical fertilizers and their combinations on growth, yield and quality of onion.

Material And Methods

A field experiment was conducted at the Agronomy Farm, Department of Agronomy, B. A. College of Agriculture, Anand Agricultural University, Anand to study the effect of combined application of organic and inorganic fertilizers on growth, yield and quality of onion bulb (Allium cepaL.) during the years 2011-12 in rabiseason on loamy sand soil. The experiment soil was low in organic carbon (0.21%), total nitrogen (0.022 %), medium in available phosphorus (38.74 kg ha^-1) and high in available potash (287.12 kg ha^-1). There were twelve treatmentsof organic and inorganic fertilizers i.e T1 : Absolute control, T2 : RDF @ 100-75-75 NPK kg ha^-1(control), T3: NADEP compost  @ 7 ha^-1, T4 : Vermicompost  @  5 ha^-1, T5 : 75 % RDF  + NADEP compost @ 1.75 ha^-1, T6 : 50 % RDF + NADEP compost @ 3.5 ha^-1, T7 : 75 % RDF + Vermicompost @ 1.25 ha^-1, T8: 50 % RDF +  Vermicompost @ 2.5 ha^-1, T9 : 50%  RDF + NADEP compost @ 1.75 ha^-1 + Vermicompost @ 1.25 ha^-1, T10 : 50 % RDF + PSB seedling treatment @ 5 ml l^-1  (root dipping for 15 min ), T11: 50 % RDF + Azospirillum seedling treatment @ 5 ml l^-1   (root dipping for 15 min ) and T12 : 50 % RDF + PSB seedling treatment @ 5 ml l^-1+ Azospirillum seedling treatment @ 5 ml l^-1   (root dipping for 15 min ) and experiment was laid out in randomized block design with four replications.

Table 1:Effect of nutrient management on plant height, total soluble solids and bulb yield of onion

Results and Discussion

The result summarized in Table. 1 indicated that an application of nitrogen exerted its significant influence on plant height at 40 and 80 DATP,Though, this treatment was remained statistically at par with treatments T₂ (RDF @ 100-75-75 NPK kg ha^-1), T₅ (75 % RDF + NADEP compost @ 1.75 t ha^-1), T₆ (50 % RDF + NADEP compost @ 3.5 t ha^-1), T₈ (50 % RDF + Vermicompost @ 2.5 t ha^-1), T₉ (50%  RDF + NADEP compost @ 1.75  t ha^-1 + Vermicompost @ 1.25 t ha^-1) with each others. Higher growth parameter of onion crop recorded with 75 % RDF + Vermicompost @ 1.25 t ha^-1 might be due to ample supply of nitrogen which encourages the vegetative growth and also led to carbohydrate formation. Nitrogen is also being constituent of chlorophyll, amino acids, proteins and nucleic acid which promotes the cell multiplication and cell elongation, which ultimately accelerate the vegetative growth and vermicompost which contains all essential plant nutrients in appropriate proportions and provides the soil with more stable humus.These findings are in agreement with those ofDevi and limi ado (2005), Balemi et al. (2007), Mozumder et al. (2007) and Adagale et al. (2009).

Effect of total soluble salt was found to be non-significant during the investigation, however treatment T7 noted higher total soluble salt (13.38 %) among other treatment.These results are agreement with those of Saimbi and Randhawa (1983), Ethel Ngullies et al. (2009), Hari et al. (2009).

The bulb yield was significantly higher under the treatment T7 (75 % RDF + Vermicompost 1.25 ha^-1) i.e. 33.33 ha^-1, and it was remained  at  par  with treatments T2 (RDF @ 100-75-75 NPK kg ha^-1 ),T5 (75 % RDF + NADEP compost @ 1.75 ha^-1), T6 (50 % RDF + NADEP  compost  @  3.5 ha^-1),  T8  (50 % RDF + Vermicompost  @ 2.5 ha^-1)  and T9 (50%  RDF + NADEP compost @ 1.75  ha^-1 + Vermicompost @1.25 ha^-1) with each others. However, minimum bulb yield was observed   under   the treatment T1   (Absolute control) i.e. 24.07(ha^-1).The increase in bulb yield with the treatment T7 was might be due to increase in weight and volume of bulb observed in present investigations. These are the important yield parameters and their component effects might have result into higher bulb yield. The other probable reason may be due to better root proliferation, more uptakes of nutrient, higher number of leaves, and more photosynthesis and enhances food accumulation which ultimately increase bulb.The increase in bulb yield due to integrated nitrogen levels was also reported by number of workers viz., Kumar et al., (2006), Islam et al., (2008), Navale et al., (2008), Saxena et al., (2008), Sharma et al., (2009), Abdisa et al., (2011), Ethel Ngullie et al., (2011), Begali et al., (2012).

Table 2: Economics Of Different Treatments

Economics

The data on economics  presented in Table-2 indicated that application of 75 % RDF + Vermicompost @ 1.25 ha^-1 (T7) registered the highest net realization of 1,18,637 ` ha<sup>-1</sup> with the highest ICBR of 1:3.44 followed by 75 % RDF + NADEP compost @ 1.75 ha<sup>-1</sup> (T5) with net realization of 1,03,677 ` ha^-1 and  ICBR of 1:2.50. Whereas, the treatment T3 (NADEP compost  @ 7 ha^-1) recorded the lowest net realization of 71,952 ` ha^-1 with the lowest  ICBR of 1:0.18.

References

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