MSc

The study entitled “Integrated nutrient management in sorghum (Sorghum bicolor
L. Moench) for AEU 8” was undertaken at College of Agriculture, Vellayani during
2020-2022 to standardize the integrated nutrient management practices for grain sorghum
and to work out the economics of cultivation.
The field experiment carried out during December 2021 to April 2022, was laid
out in randomized block design with (3 x 3) +1 treatments replicated thrice, at
Instructional Farm, Vellayani delineated under AEU 8.The crop variety used in the study
was SPV 2217. The treatments comprised three levels of biofertilizers (B) [b1 - No
biofertilizer application, b2 - PGPR Mix I liquid formulation (5 %), b3 - PGPR Mix I
powder formulation] and three levels of N substitution with organic sources (S) [s1 - 25 %
N substitution through poultry manure, s2 – 25 % N substitution through vermicompost, s3
- 25 % N substitution through FYM] and KAU POP as the control. The recommended
dose of nutrients was given at the rate of 45:25:25 kg NPK ha-1 along with FYM (5 t ha-1)
as per KAU POP recommendation. Nitrogen was partially substituted through organic
manures on N equivalent basis as per the treatments. P and K were given through
chemical sources as basal. Organic manures for N substitution were given as basal dose.
The chemical source of N was applied in two equal splits, half as basal and the rest 30
days after sowing. Both liquid and powder formulations of PGPR Mix I developed from
the Department of Agricultural Microbiology, College of Agriculture, Vellayani, were
used as biofertilizers in the study. Seed treatment was done with PGPR Mix I (at the rate
of 30 g kg-1 seeds) followed by its soil application at the rate of 150 g m-2 area (dry cow
dung and PGPR Mix 1 in 50:1 proportion -w/w) at planting, 15 days after emergence
(DAE) and 30 DAE in b3. The liquid formulation of PGPR Mix I (5 %) was given as seed
treatment, followed by drenching (500 mL m-2) at collar region at 15 and 30 DAE. The
salient findings of the study are abstracted below.
Among different levels of biofertilizer application, significantly taller plants and
more number of leaves per plant were recorded with b2 (PGPR Mix I liquid formulation -
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5 %) at 60 and 90 DAE, whereas at harvest taller plants were recorded with b3 (PGPR
Mix I powder formulation). The leaf area per plant and LAI at 30 and 60 DAE, rooting
depth, root volume and dry matter production at harvest (8508 kg ha-1) were significantly
higher in b2. The lowest number of days to 50 per cent flowering (78.78 days) and highest
chlorophyll content at 60 DAE were recorded in b2. Yield attributes like panicle length
(20.48 cm), number of grains per panicle (2460.94) and grain weight per panicle (62.45 g)
and grain yield (3141 kg ha-1) and green stover yield (16106 kg ha-1) were higher with b2.
Crude protein content of the grain (8.48 per cent) and plant N, P and K uptake (91.77 kg
ha-1, 55.50 kg ha-1 and 196.16 kg ha-1 respectively) were the highest with b2. The
available soil P status was also significantly higher under treatment b2.
Among N substitution with organic sources, significantly taller plants and more
number of leaves per plant were recorded with s1 (25 % N substitution through poultry
manure at 60 DAE). Leaf area and LAI at 30 and 60 DAE, root volume, DMP at harvest
(8119 kg ha-1), number of grains per panicle (2035.21) and grain yield (3023 kg ha-1)
were significantly higher in s1. Rooting depth and grain weight per panicle (48.49 g) were
superior in s2 (25 % N substitution through vermicompost). The uptake of N and P were
significantly higher in s1.
The interaction effect was significant only in the case of plant height and
chlorophyll content at 60 DAE, root volume and grain yield. The treatment combination
b3s1 produced the taller plants which was on par with b2s1 and b2s2. Significantly higher
root volume and grain yield were recorded in the treatment combination b2s1 and the
highest chlorophyll content was recorded in b2s3. The highest net income (₹ 52060 ha-1)
and B:C ratio (1.99) were recorded in b2s1.
For getting higher yield, higher net returns from sorghum cultivation and also for
soil health sustenance, application of FYM at the rate of 5 t ha-1 as basal and NPK at the
rate 45:25:25 kg ha-1 wherein 25 per cent N dose is substituted through poultry manure
was found to be effective. This combined with the application of PGPR Mix I liquid
formulation (5 per cent) as seed treatment and drenching at collar region at 15 and 30
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DAE can be recommended as an INM practice for sorghum in AEU 8. The KAU POP
practice (control) was also found to be equally effective as the INM practices with respect to the growth and yield of sorghum.