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E. JEEVANA LAKSHMI*, P.V. RAMESH BABU, G. PRABHAKAR REDDY, P. UMAMAHESWARI AND A. PRATAP KUMAR REDDY
Department of Agronomy, S.V. Agricultural College, ANGRAU, Tirupati-517 502, Chittoor Dt., A.P.
A field experiment was conducted during rabi, 2016-17 on sandy loam soils of college farm, Agricultural College, Mahanandi to study the effect of foliar sprays of secondary nutrients and zinc nutrition on growth, yield attributes and yield of blackgram. The experiment comprised of eight treatments viz., control (T1), RDF (20-50-0 kg N-P2O5-K2O ha-1) (T2), RDF + foliar applica-tion of one per cent CaNO3 (T 3), RDF + foliar application of one per cent MgNO3 (T4), RDF + foliar application of one per cent Sulphur (T5), RDF + foliar application of one per cent each of CaNO3, MgNO3 and Sulphur (T6), RDF + foliar application of ZnSO4 @ 0.2 per cent (T7), T6 + foliar application of ZnSO4 @ 0.2 per cent (T8). The results revealed that all the growth parameters, yield attributes and yield were significantly higher with the foliar spray of secondary nutrients (Ca, Mg and Sulphur) and zinc at 25 and 45 DAS along with recommended dose of fertilizers (T8).
Secondary nutrients, zinc, growth parameters, yield and blackgram.
Pulses are integral part of human diet providing a major source of dietary protein. Blackgram is one among these food legumes which is well suited under intensive cropping systems due to its short duration. In India, blackgram is cultivated in an area of 2.346 M ha with a production of 1.959 M t.
In Andhra Pradesh, it occupies an area of 0.315 M ha producing 0.298 M t. The average productivity of blackgram in Andhra Pradesh (946 kg ha-1) is high as compared to India’s productivity (604 kg ha-1) (Indiastat, 2015), Being leguminous crops pulses were ignored in the aspect of nutrient management which is of great concern.
Blackgram as a pulse specially need more amounts of Ca, Mg and S. The supplementation of these essential nutrients through soil application is a common practice. But soil applied nutrients may or may not be available to plants due to several soil physico-chemical reactions and the entire fertilizer is not utilized by the crop within the season especially relating to their short duration. The excess fertilizers not only increase the cost of cultivation but also pollute the dynamic soil system. Hence, supplying these small amounts through foliage improves the quality
of produce by reaching the site of food synthesis directly and preserving the crop yields with low environmental impact.
A field experiment was conducted during rabi, 2016-17 on sandy loam soils of college farm, Agricultural College, Mahanandi, Andhra Pradesh. The soil was neutral in reaction, high in phosphorus, potassium and sulphur, medium in calcium, low in magnesium and nearly medium in zinc. The experiment comprised of eight treatments viz., control (T1), RDF (20-50-0 kg N-P2O5-K2O ha-1) (T2), RDF + foliar application of one per cent CaNO3 (T3), RDF + foliar application of one per cent MgNO3 (T4), RDF + foliar application of one per cent sulphur (T5), RDF + foliar application of one per cent each of CaNO3, MgNO3 and sulphur (T6), RDF + foliar application of ZnSO4 @ 0.2 per cent (T7), T6 + foliar application of ZnSO4 @ 0.2 per cent (T8).The test variety was TBG-104. The trail was laid out in RBD replicated thrice. The foliar spray of nutrients was carried out at 25 and 45 DAS @ 500 l ha-1. Five plants in each plot were marked separately for non destructive sampling and destructive samples were drawn from the gross plot leaving the extreme border row. Statistical significance was tested by ‘F’ value at 5 per cent level of probability
and wherever the ‘F’ value was found significant, critical difference was worked out and the values were furnished.
The results of the investigation revealed that, the growth parameters (plant height, leaf area and dry matter production) of blackgram were significantly influenced by foliar application of secondary nutrients and zinc (Table 1.). The highest values of growth parameters were recorded with T6 + foliar application ZnSO4 @ 0.2 per cent (T8) treatment, however it was comparable with RDF
+ foliar application of one per cent each of CaNO3, MgNO3 and sulphur (T6) treatment.The treatment control (T1) recorded significantly lowest values of plant height and dry matter production over the rest of the treatments tried during the experimentation.
With regard to individual foliar sprays of secondary nutrients and zinc, RDF + foliar application of one per cent MgNO3 (T4) treatment recorded higher growth parameters and was at par with RDF + foliar application of one per cent CaNO3 (T3) treatment. While, RDF + foliar application of one per cent sulphur (T5) was comparable with RDF + foliar application ZnSO4 @ 0.2 per cent (T7)
treatment which in turn was on par with RDF (T2) for all the growth parameters recorded.
The combined spray of nutrients i.e. T6 + foliar application of ZnSO4 @ 0.2 per cent (T8) treatment recorded highest growth parameters and this might be due to the balanced supply of the nutrients which promoted the plant growth processes. In addition to secondary nutrients zinc might have played an important role in the production of IAA and there by increased the growth characters. The increments in the growth traits through magnesium foliar application might be due to its role in the synthesis of metabolic products and activation of many enzymes which in turn affect the plant growth. Similar results of increase in the growth parameters with foliar application of magnesium and calcium were reported by Rady and Osman (2010) and Deotale et al. (2015).
Yield attributes (number of pods plant-1, seeds pod-1 and 1000 seed weight) and yield were highest with the application of T6 + foliar application ZnSO4 @ 0.2 per cent (T8) treatment which was at par with RDF + foliar application of one per cent each of CaNO3, MgNO3 and sulphur (T6) (Table 2 and 3). Regarding harvest index all
the foliar spray treatments except control (T1) and RDF (T2) were on par with each other.
Among the individual foliar sprays of secondary nutrients and zinc, RDF + foliar application of one per cent MgNO3 (T4) treatment achieved higher values of yield attributes and yield which was comparable with + foliar application of one per cent CaNO3 (T3) treatment However, 1000-seed weight was higher with RDF + foliar application of one per cent sulphur (T5) treatment. RDF
+ foliar application ZnSO4 @ 0.2 per cent (T7) treatment recorded non significant increase over RDF (T2) with regard to all the yield attributes and yield.
Higher yield attributes and yield were noticed with the combined foliar spray of secondary nutrients and zinc which might be attributed due to added advantage of zinc to secondary nutrients leading to optimum availability of nutrients for luxurious crop growth and efficient partitioning of assimilates from source to sink (Prasanna et al., 2013). Choudhary et al. (2014) found higher seed yield with foliar spray of S and Zn, while Veerabhadrappa and Yeledhalli (2005) with Ca and S. Among the individual secondary nutrient foliar sprays, MgNO3 foliar spray found to be promising in obtaining the higher number of pods plant-1 which correlates strongest to the yield and this might be due to enhanced chlorophyll concentration and photosynthetic rate supplying assimilates to developing pods (Neuhaus et al., 2014). Foliar application of sulphur had profound influence on the 1000 seed weight as sulphur being a part of amino acids it might have activated the enzymes and seed formation. These results were also supported by Sarkar and Pal (2006) and Gokila et al. (2015).