Influence of Iron Nutrition and Arbuscular Mycorrhiza on Yield and Economics of Hybrid Maize in Calcareous Soil

Field experiment was conducted at the Department

Mycorrhiza is the symbiosis between the roots of most land plants and many soil fungi that colonize the cortical tissue of roots during periods of active plant growth, from which both partners benefit. Arbuscular mycorrhiza (AM) are the most common mycorrhiza. Arbuscular mycorrhizal fungi are widespread and agronomically important plant symbiont and often stimulate plant uptake of nutrients such as P, Zn, Cu, and Fe in deficient soils (Liu et al., 2000). The micronutrient improvement in mycorrhizal plants is always associated with rhizosphere acidification (Dodd et al., 1987), more external mycelium in the soil (Jakobsen et al., 1992) and soil biochemical changes (Subramanian and Charest, 2007). Subramanian et al. (2009) reported that AM inoculation at varying levels of Zn concentrations exhibited prominent increase in yield components such as cob length, cob girth, row cob-1, grains row-1 and test weight of maize. AM fungus Glomus *Corresponding author email: aman_agron@yahoo.co.in intraradices enhanced the yield of sorghum plants under drought conditions (Ibrahim et al., 1990). G.mosseae inoculation increased maize grain yield over uninoculated control in nonfumigated soil (Khadge et al., 1992). Ziaeian and Malakouti (2001) concluded that Fe fertilization caused significant increase in grain and straw yield, 1000grain weight and the number of seeds per spikelet. With the application of Fe, their concentration and total uptake in grain and flag leaves and the grain protein content also increased significantly.
The AM isolates improve Fe acquisition in maize grown under Fe deficiency conditions. Improved host plant, root development, morphology and acquisition of P may have been involved in enhanced Fe acquisition by AM plants (Clark and Zeto, 1996). AM inoculated plants may mobilize or take up iron from calcareous soil low in Fe and translocate it to maize plants. With these ideas in view, the present investigation was carried out to study the influence of iron and AM inoculation on yield attributes, yield and economics of hybrid maize in calcareous soil.

Materials and Methods
A field experiment was conducted during the Kharif season of 2010 at Tamil Nadu Agricultural University, Coimbatore. The experimental soil was sandy clay loam in texture having a pH of 7.58. The fertility status was low in available N (220 Kg ha-1), medium in available P (13.1 Kg ha-1) and high in available K (457 Kg ha-1). The available Fe (DTPAextractable) content was 2.24 mg kg-1.
Hybrid maize (CO H(M)5) was used as test crop and it was grown by adopting a spacing of 60 x 25 cm. Seeds of maize hybrids under AM inoculation treatments were sown with vermiculite based mycorrhizal inoculum at 100 kg ha-1 at a depth of 3 cm below the seeds. Uniform fertilizer schedule was followed at the rate of 150: 75: 75 NPK kg ha-1. Nitrogen was applied in three splits viz., 25, 50 and 25 per cent as basal, 25 and 45 days after sowing, respectively. The entire dose of phosphorus was applied basally. The potassium was applied in two equal split doses viz., basal and at 45 days after sowing. Iron was applied basally and foliar spray of 0.5% FeSO4. Foliar spray was given twice at 35 and 45 days after sowing. During the course of investigation, yield attributes and yield were recorded and economics computed.

Yield attributes
The yield attributes of hybrid maize viz., cob weight and test weight were the highest with application of 50 kg FeSO4 + 0.5% FeSO4 foliar spray followed by 25 kg FeSO4 + 0.5% FeSO4 foliar spray and were comparable with each other (Table 1). This might be due to increased availability and better uptake of iron and all the other nutrients which might have resulted in the improvement in all the yield attributes. Ramu and Reddy (2007) reported that yield attributes of maize were higher with foliar application of Fe and Zn. Inoculation of mycorrhiza positively influenced the yield attributes. The meristems originating ears are formed at early maize developmental stage, an improved nutrition at those stages increase the number of kernels formed and filled (Barry and Miller, 1989). AM inoculation significantly increased the yield attributes. This might be due to the formation of external mycelium around the roots by AMF fungi which made the availability of all the nutrients better for crop uptake. Similar result was obtained by Ananthi, (2010) in hybrid maize.

Grain yield
Application of 50 kg FeSO4 + 0.5% FeSO 4 FS recorded the highest grain yield of 5752 kg ha-1 followed by 25 kg FeSO4 + 0.5% FeSO4 FS and 50 kg FeSO4 and both were comparable with each other (Table 1). This increase in yield was due to effective utilization of applied nutrients. The positive and significant improvement in LAI and DMP noticed at different stages, increased yield attributes and nutrient uptake due to both soil and foliar application of FeSO4 would have resulted in enhanced grain yield. The results are in conformity with the findings of Amanullah et al., (2007) in sorghum and Ramu and Reddy (2007). Inoculation of mycorrhiza significantly influenced grain yield (5820 kg ha-1). This yield gain in mycorrhizal plants caused by the intense flow of minerals and metabolites from the leaf to the developing kernel. A higher yield of maize due to mycorrhizal inoculation has been reported previously by Solaiman and Harita (1998).

Stover yield
The stover yield recorded treatment wise showed that Fe application either through soil or foliar had influenced significantly registering the highest value (Table 1). The treatment 25 kg FeSO4 + 0.5% FeSO4 FS (8937 kg ha-1) recorded the highest yield followed by 50 kg FeSO4 + 0.5% FeSO4 FS and 50 kg FeSO4 and both were comparable with each other. The application of FeSO4 either soil or foliar would help to recover the crop from chlorosis and yield well especially in calcareous soil. AM inoculation significantly influenced the stover yield. AM inoculated plants recorded significantly higher (9076 kg ha-1) stover yield. It is due to increase in growth parameters as evidenced in the present investigation. Similar results of increase in stover yield due to mycorrhizal inoculation were also reported earlier by Lauzon and Miller (1997) and Ananthi (2010) in maize.

Economics
The highest gross return was recorded with application of 25 kg FeSO4 + 0.5% FeSO4 foliar spray 487 followed by 50 kg FeSO4 + 0.5% FeSO4 foliar spray (Table 2). It is obvious that a realization of higher gross return was the result of higher yield. Remunerative economic returns (net return and B: C ratio) play a key role to convince the farmers for adoption of any refined version of agro techniques. In the present study, higher yields as well as high The study revealed that 50 kg FeSO4 + 0.5% FeSO4 FS, AM inoculation recorded better yield attributes and yield. It was comparable with 50 kg FeSO4 + 0.5% FeSO4 FS along with AM inoculation. Iron applied at 25 kg FeSO4 + 0.5% FeSO4 FS along with AM inoculation enhanced the grain yield of maize and net profit in calcareous soil.