On Farm Testing on Foliar Application of Nutrients and Growth Regulators in Pigeonpea (Cajanus cajan L.)

Pigeon pea (Cajanaus cajan), also known as redgram or arhar or tur, is an annual legume from the family Fabaceae. Since its domestication in the Indian subcontinent 3500 years ago, its seeds have become a common food in Asia, Africa and Latin America and consumed on a large scale in South Asia. Thus it is a major source of protein for the population of the Indian sub-continent. Globally, redgram is grown in an area of 60.96 lakh hectares with a production of 50.12 lakh tonnes and productivity of 822.2 kg/ha (FAOSTAT, 2020). India ranks first in redgram production globally with 42.8 lakh tonnes cultivated under 48.24 lakh hectares with productivity of 887 kg/hectare in 2020-21 (agricoop.nic.in). In kharif 2021-22, total produduction of redgram production was 44.3 lakh tonnes (1st advance estimates) from an estimated area of 50.02 lakh hectares (agricoop.nic). Andhra Pradesh produced 0.84 lakh tonnes contributing 1.96% to total India’s production cultivated in an area of 2.31 lakh hectares with 363 kg/hectare productivity in 2020-21. Kurnool is the second largest area in Andhra Pradesh and mostly cultivated during kharif season under rainfed conditions an area of 71840 hectares and production of 19095 MT in the district (2021-22). (http://www.indiastat.com).
       
The productivity of pigeonpea in Andhra Pradesh is very low (536 kg/ha), compared to Bihar which is highest in productivity (1695 kg/ha). (DES, 2015-16). Thus there is need for enhancement of the productivity of pigeonpea by proper agronomic practices. One among them is foliar application of nutrient sources for exploiting genetic potential of the crop. This is considered to be an efficient and economic method of supplementing part of nutrients requirement of critical stages. Nutrients play a pivotal role in increasing seed yields in pigeonpea (Manonmani and Srimathi, 2009). Nutrient management in pigeonpea follows application as basal dose only which might be the requirement for first formed flowers. To exploit yield potential of the crop, the second formed fleshes also needs nourishment. This triggers the need to supplement the nutritional needs through other methods. One among them is foliar application of nutrients and growth regulators considered to be an efficient and economic method of supplementing part of nutrients requirement at critical stages. Foliar application is credited with the advantage of quick and efficient utilization of nutrients due to direct entry into the plants via cuticle or stomata besides reducing the losses through leaching and soil fixation (Manonmani and Srimathi, 2009). Foliar application of N at particular stage may solve the slow growth, nodule senescence and low seed yield of pulse without involving root absorption at critical stage (Devaraju and Senthivel 2018). Foliar application of nutrient and growth regulator at pre-flowering and flowering stage was seen on reduction in flower drop percentage in black gram (Ganapathy et al., 2008). To exploit yield potential of the crop, the second formed fleshes also need nourishment. Keeping  this in view  an onfarm study was planned with foliar spray of nutrients and growth regulators involving TNAU Pulse wonder and 2% DAP along with recommended dose of fertilizers during three kharif seasons from 2018-19 to 2020-21.

Krishi Vigyan Kendra, Banavasi, carried out the study on the technologies in the farmers fields through 30 Onfarm testings during kharif season from 2018 to 2020 in the three mandals viz.,Yemmiganur, Adoni and kodumuru  of Kurnool district in Andhra Pradesh. Farmers who are practicing indiscriminate and excess application of fertilizers were selected from different villages with same soil type. The experiment consisted of 7 technology options (treatments).
       
T₁: consisting recommended dose of fertilizers (20:50:0 NPK kg ha^-1) along with spraying of pulse wonder  @ 5 kg ha^-1 during flowering and 15 days after 1^st spray, T₂ : 75% RDF + Pulse wonder 5 kg  ha^-1 at flowering, T₃ : 50% RDF + Pulse wonder 5 kg  ha^-1 at flowering, T₄ : 100% RDF+ 2% DAP at flowering and pod formation stage T₅ : 100% RDF alone (20:50: 0 NPK kg ha^-1), T₆: Farmers practice (30: 60: 10 NPK kg ha^-1), T7: control. Pigeonpea variety LRG-52 was used for this study. Seeds were sown with the spacing of 90 × 20 cm. Recommended dose of fertilizers were calculated as per treatments were applied as basal. The required quantity of foliar nutrients and water for each plot were calculated to prepare solution and sprayed uniformly by hand sprayer using conical shaped nozzle. 2% DAP solution was prepared and sprayed during flowering and pod formation stages. TNAU Pulse wonder @ 5 kg ha^-1 was sprayed during flowering stage. The pigeonpea crop was harvested, when the pods were fully ripened and turned brown. Threshed seeds were sun-dried for 2-3 days to reduce the moisture content and then the seed yield per plot was recorded. During these period regular visits by Krishi Vigyan Kendra, Banavasi Scientists to Onfarm testing plots were made to supervise important farm operations. The extension activities like training programmes, group meetings and field days were also organized at the demonstration sites as to provide opportunities for other farmers of that area to interact and to seek benefits from these demonstrations. Observations on growth, yield attributes and yield were analysed and expressed as means of three replicates (n) ± standard deviation. Data were statistically analyzed with R software. To elucidate significant differences between means (p<0.05), post hoc comparisons were made using Tukey’s HSD. The correlation matrix was created using R studio version 1.4.1717 utilizing the ‘ggcorrplot’ package. Economics were calculated based on the prevailing market price of the vegetable cowpea and labour wages / man day.  The input and output prices of the commodities prevailing during the study were taken into an account for calculating the net returns and benefit-cost ratio.

Growth
 
Plant height and number of flowers per plant were significantly influenced by fertilizer levels and foliar spraying of pulse wonder and 2% DAP. In the year 2018-19 the application of 100 % recommended dose of fertilizers in combination pulse wonder @ 5 kg ha^-1 during flowering and 15 days after 1^st spray (T₁) recorded maximum plant height and number of flowers per plant  which was significantly superior than rest of treatments, expect application of DAP @ 1% flowering and 15 days after 1^st spray (T₄). The minimum height of the plant height and number of flowers per plant were  recorded in control treatment. (Table 1). The flower shedding was lowest in T₁ and maximum flower shedding was observed in T₇ (Fig 1). Same trend was  also observed in the years 2019-20 and 2020-21 (Table 2 and 3) The significant increase of plant height was due to the inter node elongation and the vigorous root growth of the crop. This might be due to better absorption of nutrients applied through foliage leading to better activity of functional root nodules resulting in more leaf area, dry matter production and uptake of nutrients. This could have led to more flower production and subsequently low flower shedding .The application of TNAU pulse wonder and DAP as foliar spray significantly improves the yield attributing characters by reducing flower shedding and resulted in increse number of pods/plant (Ravisankar et al., 2003 and Babu, 2003).
 

 

 

 

 
Yield and yield attributes
 
Foliar application of  pulse wonder @ 5 kg/ha at flowering and 15 days after the 1^st spray of crop growth resulted in significantly highest test weight and seed yield than other foliar spray treatments . The yield was however onpar with T₄ (100% RDF+ 2% DAP at flowering and pod formation stage) in the year 2018-19. (Table 1). Similar results were obtained in the years 2019-20 and 2020-21 (Table 2 and 3). The increase in yield might be due to reduce in flower shedding. Higher availability nutrients at flower initiation and pod formation stages of crop growth and efficient translocation of photosynthates from source to sink. It is due to increased uptake of nutrients by pieonpea by effective translocation of nutrients from sink to reproductive area of crop. The results are also in accordance with (Kavitha et al., 2019).
 
Correlation analysis
 
The correlation heat maps present the types of correlations between the different pigeonpea growth and yield parameters (Fig 2, 3 and 4). It appears that some parameters are either positively or negatively correlated to others with positive values dark red and the negative values in blue. The strongest correlations are obtained between PY and FP, TW and PH. This implies that value increase of one of this parameter leads to the increase of the parameter to which it is significantly correlated. The strongest negative correlation is between PY and FS. Pod yield was positively correlated with number of flowers plant^-1 (r value 0.813, 0.762 and 0.735) and test weight (r value 0.795, 0.8 and 0.754)  and negatively correlated with flower shedding. (r value -0.788,-0.712 and -0.750) in 2018-19,2019-20 and 2020-21 years respectively. This indicates lower flower shedding significantly increases the yield. This trend was observed in all the three years of the experiment.
 

 

 

 
Regression analysis
 
Quadratic response regression analysis on the grain yield of pigeonpea was predicted for the impact of number of flowers per plant and test weight  the results indicated that the increase in these parameters has significant effect on grain yield of pigeonpea , as shown in the graph with the R² value and polynomial equation (Fig 5 and 6). For instance polynomial equation Pod yield kg/ha = 440.21094+10.14035 *No of flowers/plant with the R² value of 0.6608 was observed for number of flowers per plant with grain yield in the year 2018-19. Similar trend was observed with other parameters (test weight with Fig 4 and 5). The final yield of crop is the cumulative effects of growth attributes. The treatments which promote the favorable parameters could result in the positive relationship with higher productivity as observed in the current study. Similar findings were recorded in blackgram by Marimuthu and Surendranin (2015).
 

 

 
Economics
 
Foliar application of pulse wonder @ 5 kg/ha flowering and 15 days after 1^st DAS spray (T₁) recorded higher average benefit: cost ratio of 4.01 followed by application of 100% RDF+ 2% DAP at flowering and pod formation stage (T₄) (Fig 7). Some of the earlier study also reported that foliar spray of pulse wonder DAP, NAA and micronutrients significantly improved seed yield of green gram and highest benefit cost ratio (Marimuthu and Surendran 2015). The lowest benefit: cost ratio of 3.04 was recorded in a farmer’s practice T₆ ( 30 :60: 10 NPK kg ha^-1).
 

The present investigation concluded that application of foliar application of TNAU pulse wonder @ 5 kg/ha at flowering and 15 days after 1^st spray can be recommended to realize the genetic potential of the variety under test with higher profitability of pigeonpea in Scarce  Rainfall Zone of Andhra Pradesh, India.

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