Targeted Yield Equation for Marigold in Laterite Soils of Odisha

Due to a greater focus on food grain farming, India’s floriculture business has grown relatively slowly throughout the first 40 years of independence. However, following the liberalization of economic policies in the 1990s, there was a notable increase in the production of loose flowers in floriculture, with production rising from 233 thousand tonnes in 1993-1994 and only 53 thousand hectares in 1993-1994 to an astounding 3.09 lakh hectares in 2016-17 (Kumar et al., 2011). In Odisha, marigold production experienced remarkable growth, increasing from 14,581 quintals in 2003-04 to 2,45,810 quintals in 2013-14 (Das et al., 2020). The state has 2.05 thousand hectares dedicated to marigold cultivation, with a production output of 12.82 thousand metric tons (Indian Horticulture Database, 2017). Apart from agro-climatic advantage our country also enjoys the geographic advantage of being situated between two big markets Europe and South-East Asia, which makes trade easy (Verma and Singh, 2021).
       
The marigold (Tagetes spp.), a member of the Asteraceae family, is a significant loose flower farmed commercially worldwide. African marigold has gained popularity because flower farmers have been drawn to its vast range of eye-catching colors, shapes and good-keeping qualities. One of the most significant commercial loose flower crops, marigold is farmed in practically every Indian state. Odisha has a good capacity for production because of the appropriate soil and climate conditions.
       
Nutrition is one of the key factors affecting the growth and yield of marigold among various agro-techniques. While soil testing has become a vital tool for recommending fertilizer dosages for different crops in India, its effectiveness relies on a comprehensive understanding of the interactions between soil, crop variety, fertilizer and climate management in a specific context (Kanwar, 1971). The targeted yield strategy has proven to be more precise, facilitating the recommendation of balanced fertilization that aligns crop requirements with the soil’s available nutrient status. This approach is highly effective as it integrates the nutrient availability in the soil with the crop’s needs. The concept of targeted yield is based on a significant linear relationship between crop yield and nutrient uptake. It was first proposed by Troug (1960) and later refined by Ramamoorthy et al., (1967).
       
According to soil taxonomy, the soils of Odisha are classified into four orders: Inceptisols (49%), Alfisols (35%), Entisols (10%) and Vertisols (6%) (Sahu and Mishra, 2005). Approximately 60% of Odisha’s soils have medium organic carbon content, while 40% are low in organic carbon. In terms of available phosphorus (P), 73% of soils are medium and 27% are low. For potassium (K), 7% of soils are low, 86% are medium and 7% are high. Fertilizer prescription equations have been developed for field crops such as Pumpkin (Gogoi et al., 2011), Okra (Mishra et al., 2013), Tomato (Mishra et al., 2013), Chilli (Mishra et al., 2013)  and French Bean (Pogula et al., 2016). While several crops, including have performed well under Odisha’s soil conditions, no equivalent fertilizer prescription equations have been established for flower crops.

The field and laboratory investigation was conducted from October 2019 to June 2022 at the Biotechnology-cum-Tissue Culture Center (BTCC), Department of Floriculture and Landscaping, College of Agriculture, Odisha University of Agriculture and Technology, Bhubaneswar, Odisha.
       
All the treatments were randomized separately in each replication. The experimental design followed was randomized block design (RBD). The 24 treatments were selected with three replicates each consisting of T₁ NPK 0:80:80 kg/ha, T₂ NPK 60:60:60 kg/ha, T₃ NPK 60:60:80 kg/ha, T₄ NPK 60:80:80 kg/ha, T₅ NPK 60:80:80 kg/ha, T₆ NPK 80:0:80 kg/ha, T₇ NPK 80:60:60 kg/ha, T₈ NPK 80:60:80 kg/ha, T₉ NPK 80:80:0 kg/ha, T₁₀ NPK 80:80:60 kg/ha, T₁₁ NPK 80:80:100 kg/ha, T₁₂ NPK 80:80:100 kg/ha, T₁₃ NPK 80:100:60 kg/ha, T₁₄ NPK 80:100:100 kg/ha, T₁₅ NPK 60:100:80 kg/ha, T₁₆ NPK 100:80:60 kg/ha, T₁₇ NPK 100:80:100 kg/ha, T₁₈ NPK 100:80:100 kg/ha, T₁₉ NPK 80:60:100 kg/ha, T₂₀ NPK 80:100:80 kg/ha, T₂₁ NPK 100:100:100 kg/ha, T₂₂ (Control No organic No chemical), T₂₃ FYM 5 tons/ha and T₂₄ FYM 10 tons/ha.
       
Samples of pre-sowing and post-harvest soil were obtained from the top layer (0-15 cm) in a Soil samples, both pre-sowing and post-harvest, were collected from the topsoil layer (0-15 cm). Harvesting began when the first flower reached full bloom and continued every alternate day. Tagged plants were harvested and the number of flowers from each plant was recorded separately. After harvesting, the tagged plants were uprooted, dried properly and processed along with flower samples for laboratory analysis. To estimate yield per hectare, a one-square-meter sample of the marigold crop was taken from each of the 72 treatments. The fresh weight of the flowers and plants was measured. Plant samples were partially shade-dried, then dried at 70^oC in a hot air oven and stored for chemical analysis. The nitrogen content in plant and flower samples was determined using the micro-Kjeldahl method (Jackson, 1973). Bray’s No. 1 method was used to measure the available phosphorus in soil samples (Bray et al., 1945). Potassium in the acid digest of plant samples and available potassium in the soil were analyzed using a Systronics flame photometer (Model 128).
       
Fertilizer prescription equations were created for the targeted yield concept using data on initial soil test results, fruit/flower yield, biomass yield and crop nutrient uptake. The essential basic data required for formulating fertilizer recommendations for targeted yield are Nutrient requirement in kg q^-1 of produce, grain, or other economic produce (NR), Per cent contribution from the soil available nutrients (C_S), Per cent contribution from the applied fertilizer nutrient (C_f) and per cent contribution from the applied organic matter (C_FYM).
 

Flower yield
 
Variation was observed in the range of 559.15-1008.3 g for the weight of flowers per plant. The highest value for this character was for the nutrient dose T21 NPK 100:100:100 kg/ha (1008.31 g). The Range and Mean values of flower yield and nutrient uptake in African Marigold for 3 seasons are presented in Table 1.


       
NPK plays a vital role in boosting flower yields in ornamental plants (Kashif, 2001). Various factors influence yield, including plant height, number of leaves, lateral branches, flowers per plant, flower weight and nutrient uptake by the plant (Naik, 2015) and (Baskaran and Abirami 2017). Increasing NPK dosages significantly improved both the number and weight of flowers per plant (g) and per hectare, along with the overall accumulation of fresh and dry plant biomass. The positive impact of potassium on marigold growth can be attributed to its role in peptide bond synthesis, protein and glucose metabolism and promoting rapid cell division and differentiation (Pal and Ghosh, 2010; Panwar, 2016). These findings align with studies by Durga et al., (2017), Tripathi et al., (2020), Naik (2015), Ahmad et al., (2011) and Sonklien et al., (2020) which reported increased yields with higher doses of N, P and K.
 
Nutrient uptake
 
The nutrient uptake was increased with increased fertilizer application. Maximum Nitrogen uptake (241.38), Phosphorous uptake (49.99) and Potassium uptake (210.71) was obtained with an application of   NPK (100-100-100). Table 1 shows the Range and Mean values of nutrient uptake in African Marigold.
       
In a study, Anuradha et al., (1988) observed that the nutrient content in African marigolds (Tagetes erecta L.) varied not only with different nutrient levels but also across distinct growth stages. Their findings revealed that nitrogen (N) concentration at 30, 60 and 90 days after transplanting (DAT) significantly increased as nitrogen levels rose from 0 to 90 kg ha^-1. The uptake of nitrogen (N), phosphorus (P) and potassium (K) peaked during the full bloom stage and declined during the harvest stage. Moreover, positive interaction between organic (FYM) and inorganic (NPK) nutrients might have hastened the soil nutrient status, which in turn increased the efficiency of nutrient uptake thereby enhancing the yield as reported by Patil and Dhaduk (2009).
 
Nutrient requirement
 
The target yield model offered valuable insights into key factors such as nutrient requirements (NR) and the contributions of soil, fertilizer and farmyard manure (FYM) to total nutrient uptake. For the production of one quintal of marigold flowers, the nutrient requirements were determined to be 0.55 kg of nitrogen (N), 0.09 kg of phosphorus (P) and 0.56 kg of potassium (K), as shown in Table 2. The reduced phosphorus requirement may be due to the increased contribution from the soil, likely from the residual effects of the previous crop. Additionally, FYM improved phosphorus availability by reducing fixation and enhancing its efficiency (Mahajan et al., 2014).


 
Soil efficiency, fertilizer efficiency and organic matter efficiency of marigold
 
The per centage contribution of fertilizer nutrients was observed in the order of K > N > P, as mentioned in Table 2 aligning closely with the findings of Durga et al., (2017) and Tripathi et al., (2020). The contribution of farmyard manure (FYM) was highest for nitrogen (N), followed by phosphorus (P) and potassium (K), with values of 27.55%, 8.21% and 7.82%, respectively.
 
Formulation of targeted yield equation and ready reckoner
 
Following the approach outlined by Ramamoorthy et al., (1967), calculations were made for initial soil nutrient status, yield, nutrient uptake, nutrient requirement (NR), soil efficiency (C_S), fertilizer efficiency (C_f) and organic matter efficiency (C_FYM). These parameters were incorporated into three separate equations for nitrogen (N), phosphorus (P₂O₅) and potassium (K₂O) to determine the required fertilizer doses for achieving specific yield targets, considering each nutrient individually.
       
A ready reckoner based on marigold equations was created to provide farmers with a simple, practical tool for immediate use, as shown in Table 3. To use this ready reckoner, farmers must first assess the initial nutrient status of their soil and set a feasible yield target. This tool then recommends the appropriate fertilizer doses for marigold cultivation, customized to the desired yield and the soil’s nutrient status. The targeted yield equation for marigold is provided in Table 4.

This study resulted in the creation of fertilizer prescription equations for marigold, designed for both NPK alone and integrated nutrient management under the climatic conditions of Odisha. The nutrient requirements to produce one quintal of marigold flowers are approximately 0.55 kg of nitrogen (N), 0.09 kg of phosphorus (P) and 0.56 kg of potassium (K). The contributions to the required nutrients come from soil (23.07%, 48.01% and 40.01% for N, P and K, respectively), fertilizer (54.92%, 17.51% and 87.40% for N, P and K, respectively) and farmyard manure (27.55%, 8.21% and 7.82% for N, P and K, respectively), to achieve the targeted yield.

The present study was made possible with the support and guidance of Dr. Siddharth Kumar Palai, Professor and Head, Department of Floriculture and Landscaping, College of Agriculture, OUAT, Bhubaneswar. I am also grateful to all other authors for their valuable intel.
 
Disclaimers
 
The views and conclusions expressed in this article are solely those of the authors and do not necessarily represent the views of their affiliated institutions. The authors are responsible for the accuracy and completeness of the information provided, but do not accept any liability for any direct or indirect losses resulting from the use of this content.
 
Informed consent
 
All animal procedures for experiments were approved by the Committee of Experimental Animal Care and handling techniques were approved by the University of Animal Care Committee.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish or preparation of the manuscript.