Impact of zinc enriched pressmud compost, azophos, ZnSO4 and vermiwash for enhancing yield attributes and yield of pearl millet cv. CO7 in black soil

Introduction

Pearl millet is also called as bajra, a major coarse grain crop and poor man's staple food in dry tracts of the country. India is the largest producer of pearl millet, it occupies an area of 9.16 million hectares and production of 13.51 million tonnes with a productivity of 1.5 tonnes per hectare (USDA, 2023) [12] . Zinc is a structural constituent and regulatory co-factor in enzymes and proteins involved in many biochemical pathways (Behera and Chitdeshwari, 2021) [3] . Besides improving photosynthesis and regulation of auxin concentration, it also plays an important role in nitrogen metabolism and protein synthesis. Pressmud compost is a plentiful source of carbon for the soil besides being rich in N, P and K. The use of pressmud compost balances organic carbon content in the soil and thereby preserves optimum productivity and soil fertility (Avishek et al., 2017) [1] . The use of azophos in soil adds nutrients through natural processes viz., nitrogen fixation, phosphorus solublization and stimulating plant growth through synthesis of growth promoting substances. Vermiwash acts as a plant tonic and thus helps in reducing several plant pathogenic fungi. It increases the rate of photosynthesis in crops plants. Considering the above facts, present investigation was undertaken with the objective of to evaluate the effect of soil application of zinc enriched pressmud compost, azophos and foliar spray of ZnSO 4 and vermiwash on yield attributes and yield of pearl millet.

Materials and Methods

The field experiment was conducted in Farmer's Field at Isukkali Katteri Village, Kilpenathur Taluk in Tiruvannamalai District, Tamil Nadu, India. The pH, EC, organic carbon content of an initial soil were 8.10, 0.39 dSm -1 , 2.51 g kg -1 and taxonomically as Typic Ustropept. The study included eight treatments were T 1 -Absolute control, T 2 -100% RDF (N:P 2 O 5 :K 2 O) (80:40:40 kg ha -1 ), T 3 -Zn -EPMC @ 10 t ha -1 , T 4 -T 3 + Azophos @ 5 kg ha -1 , T 5 -T 3 + ZnSO 4 @0.5% (F.S), T 6 -T 3 + Azophos @ 5 kg ha -1 + ZnSO 4 @0.5% (F.S), T 7 -T 3 + ZnSO 4 @0.5% (F.S) + V.W @5% (F.S), T 8 -T 3 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5%(F.S) +V.W @5% (F.S). The RDF for pearl millet was 80:40:40 kg N: P 2 O 5: K 2 O ha -1 applied to through Urea, SSP and MOP, respectively. Based on treatments, Zn -EPMC @ 10 t ha -1 , azophos@ 5 kg ha -1 were applied one week before transplanting. As per the treatment schedule, ZnSO 4 @ 0.5% and vermiwash @5% were sprayed at 30 and 60 DAT during vegetative and reproductive stages, respectively. The effect of different treatments on various yield attributes viz., earhead length, earhead girth, earhead weight, 1000 grain weight and grain and stover yield were studied and recorded.

Results and Discussion

Yield attributes Earhead length

The earhead length ranged from 14.35 to 32.45 cm due to different treatments (Table 1). The earhead length was significantly high in T 8 (32.45 cm) and was followed by T 7 (29.31 cm) and T 6 (28.82 cm). T 7 was on par with T 6 . Application of 100% RDF (T 2 ) was registered the earhead length of 25.96 cm. The control (T 1 ) recorded lowest earhead length of 14.35 cm. The enhanced earhead length is attributed to the microbial stimulation effect of enriched pressmud compost, gradually providing essential nutrients throughout the growth period and sustained nutrient supply improved photosynthetic assimilation, fostering a better source-sink relationship (Gangadhar Nanda, 2015) [4] . It might be also due to the effective utilization of vermiwash which improved availability and translocation of plant nutrients along with combined beneficial effects of earthworms and micro-organisms which led to enhanced earhead length (Manoj et al., 2018) [6] .

Earhead girth

Application of Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (T 8 ) recorded significantly highest ear head girth of 8.56 cm followed by T 7 -Zn -EPMC @ 10 t ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (7.67 cm) against control T 1 (3.37 cm). It might be also due to foliar spray of zinc improved the yield attributes by improving the source and sink relation due to increased translocation of photosynthates towards reproductive system and ultimately, enhanced earhead girth. Similar results were reported by Singh et al. (2017) [11] .

Earhead weight

Among the treatments tried, application of Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (T 8 ) registered highest earhead weight of 51.98 g over control (20.35 g). The next highest earhead weight (47.88 g) noted in the treatment T 7 . However, the lowest earhead weight of 20.35 g was noticed in T 1 . The beneficial effect of yield attributes might also be owing to the supply of all the essential nutrients by Zn enriched pressmud compost that might have resulted in higher manufacture of food and its subsequent partitioning of photosynthates towards sink. These finding was similar to Seema et al. (2017) [9] .

The maximum 1000 grain weight (9.04 g) was registered with T 8 -Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO4 @ 0.5% +VW @ 5% compared to control (T 1 ) (7.89 g). It might be due to enriched pressmud compost was good in increasing 1000grain weight and cause higher moisture content. The presence of water softening agents in enriched pressmud compost facilitates rapid root expansion in moist soil conditions (Gangadhar Nanda, 2015) [4] . Azophos provides non-limiting supplies of nutrients viz., N, P and K from the soil owing to their high content increased the test weight (Hasan et al., 2013) [5] .

Yield

Grain yield (kg ha -1 ) Among the different treatments tried, highest grain yield of 3670 kg ha -1 was found to be with T 8 . The second-best grain yield (3279 kg ha -1 ) found to be with T 7 followed by T 6 recorded 3112 kg ha -1 . The treatment T 7 was statistically on par with T 6 . Application of 100% RDF (T₂) registered the grain yield of 2728 kg ha -1 . However, lowest grain yield (1379 kg ha -1 ) was observed in control (T 1 ). An increase in grain yield could be assigned to the cumulative ameliorating effect of yield parameters. The addition of enriched pressmud compost increased the organic matter and nutrient availability and reduced the uptake of toxic ions results in improved growth and yield of crops (Azhar et al., 2019) [2] . Application of azophos increased photosynthetic activity which resulted in higher accumulation of photosynthates and translocation to sink due to better source which resulted in higher grain yield.

Application of Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (T 8 ) recorded highest stover yield (7287 kg ha -1 ) was followed by T 7 registered the stover yield of 6561 kg ha -1 , respectively. The treatments T2, T 5 and T 4 recorded stover yield of 5590, 4874 and 4752 kg ha -1 , respectively. However, control recorded lowest stover yield (2925 kg ha -1 ). The positive effect on yield might be due to the use of enriched pressmud compost and bio-fertilizers increased the availability of plant nutrients and balanced supply of nutrients through compost results in better growth and development of crop, increased fertile ear heads, number of grains ear head -1 and test weight which led to increased stover yield. (Selvamurugan et al., 2013) [10] . It might be also due to the fact that phytohormones produced by the azophos (Azospirillum + PSB) stimulated root growth and induced changes in root morphology, which in turn affected the assimilation of nutrients. Vermiwash was rich source of macro and micronutrients, enzymes and growth regulator, which improved the stover yield because of increasing the dry matter production. (Naroila and Poonia, 2011) [7] .

Harvest Index

The harvest index was significantly higher in T 8 -Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (33.49). This was followed by T 7 and T 6 recorded harvest index of 33.32 and 32.99, respectively. However, lowest harvest index (32.03) was recorded in T 1 . It might be also due to profound influence of foliar spray of zinc on growth attributes as increased metabolic process in plants which promoted meristematic activities and photosynthetic process, ultimately better growth resulted in higher yield and improving harvest index (Saraswathi et al., 2019) [8] .

Conclusion

Based on the results obtained from the field experiment, it can be concluded that application of Zn -EPMC @ 10 t ha -1 + Azophos @ 5 kg ha -1 + ZnSO 4 @ 0.5% +VW @ 5% (T 8 ) registered significantly highest yield attributes and yield of pearl millet grown in clay loam soil. Adopting organic nutrients sources with zinc is an excellent approach for fostering more resilient and eco-friendly agricultural practice, in harmony with the objectives of sustainable development and food security.

References

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