PRE-HARVEST APPLICATION OF INORGANIC SOURCES OF NUTRIENT ON YIELD AND SHELF LIFE OF BROCCOLI

A study was conducted at Chanchra, Sadar Upazila, Jashore, Bangladesh during Rabi seasons of 2019-20 and 2020-21 to evaluate pre-harvest treatments of inorganic nutrient sources on yield and shelf life of broccoli following Randomized Complete Block Design (RCBD) with three replications and six treatments which were; T 1 = soil test based 50% NPK with blanket dose, T 2 = soil test based 75% NPK with blanket dose, T 3 = soil test based 100% NPK with blanket dose, T 4 = soil test based 125% NPK with blanket dose, T 5 = local farmers practice (N 138 P 75 K 94 S 27 Zn 5 kg ha -1 ),T 6 = control.Completely Randomized Design (CRD) was designed to determine the shelf life of broccoli with three replications considering three factors; (i) pre-harvest treatments of inorganic sources of nutrient; (ii) storage materials at room temperature and (iii) storage materials at cold storage condition.Findings revealed that the effects of different inorganic sources of nutrients significantly influenced on yield and shelf life of broccoli. The treatment T 3 (soil test based 100% NPK with blanket dose) resulted in better marketable curd yield with maximum gross returns, net returns and Benefit Cost Ratio (BCR) as compared to other treatments.The treatment T 1 (soil test based 50% dose of NPK with blanket dose) recorded the maximum shelf life of 6.57 daysand 6.83 days at room temperature (14-24 0 C with RH 60-65%) and 23.65 days and 24.25 days at cold storage (4 0 C with RH 90-95%) condition using High -Density Polyethylene (HDP;15 micron) vacuum pack during the years of 2019-20 and 2020-21 respectively.


INTRODUCTION
Broccoli is one of the most important high value and nutrient rich vegetables under Cole crops belongs to the family Brassicaceae. Broccoli has a reputation as a supper food and it is known to be a healthy and delectable vegetable which is wealthy in many supplements. Broccoli is a nutritional powerhouse full of vitamins, minerals, fibers and antioxidants that support many dimensions of human health (Cartea et al., 2008;Faller and Fialho, 2009;Yvette, 2012). Broccoli is also considered a low Glycemic Index (GI=10) wonder food for diabetics (Nagraj et al., 2020). Global production of broccoli was 27 million tons in 2019. Out of these, 73% broccoli production accounted by China and India. The rest of production was supplemented by USA, Mexico, Spain, Italy, Turkey, Bangladesh, Poland and France (FAOSTAT, 2020). Farmers of Bangladesh are very much interested to produce and extent broccoli for its high value.
Nutrient management plays a key role in influencing the productivity and quality of any crop. Broccoli is highly responsive to nitrogen, phosphorus and potassium in its growth and yield. Nitrogen is inextricably linked with the vegetative growth of broccoli which plays an important role in maximizing the yield of broccoli up to a certain limit. But if more nitrogen is used than the optimum rate, the desired yield of broccoli will be reduced and it may have a negative effect on the quality and preservation of broccoli (Abu, 2021). Similarly, phosphorus is another important macronutrient that also affects the growth and productivity of cauliflower and broccoli (Sonia et al., 2020). In the same way, potassium also plays a vital role in physiological activity; growth and yield balance of broccoli (Zaki et al., 2015). Adequate potassium supply ensures optimum shelf life and more marketable crops with less moisture loss during storage. Considering the abovementioned review, it is essential to recommend a dose of inorganic sources of nutrients for increasing yield, quality and shelf life of broccoli.
Preservation capability of broccoli is comparatively poor than other Cole crops such as cauliflower. Yellowing is the main problem in post-harvest life of broccoli which leads to unmarketability due to consumer dislike (Chingtham and Banik, 2019). Farmers are not aware about the shelf life of broccoli. They apply huge amount of chemical fertilizers and pesticides often overdoses, more frequencies and even mixing of two or more chemicals as cocktail formulation to achieve better yield during production (Shamsunnahar, 2016). Consequently, the storage longevity of broccoli is reduced spontaneously. In this circumstance, it is essential to improve post-harvest quality and extensionof the shelf life of the said crop. Packaging materials help not only to keep this vegetable from drying out but also to preserve nutritive value, flavour, texture and color (Raseetha et al., 2018). Polyethylene bag delayed color change due to synchronized effect of increased humidity and fluctuated atmosphere composition (Rao and Shivashankara, 2015). Vacuum pack with low temperature (storage at 4 0 C with 95% RH) is the effective technique to maintain the shelf life of broccoli (Jadhav et al., 2018). The investigator opined that pre-harvest application of judicious inorganic sources of nutrients in broccoli production and also using low cost technology such as, Low-Density Polyethylene (LDP; 35 micron) bag, High -Density Polyethylene (HDP;15 micron) vacuum pack, 2% egg shell powder and 2% ascorbic acid solution at post-harvest stage to to maintain the shelf life of broccoli. Very few investigators studied partially but not in-depth on the above context. Considering above all, the investigator would like to take an in-depth study on pre-harvest application of inorganic sources of nutrient on yield and shelf life of broccoli.

MATERIALS AND METHODS
The field experiment was conducted in the Rabi seasons at Chanchra under SadarUpazila, Jashore, Bangladesh during the years 2019-20 and 2020-21. Randomized Complete Block Design (RCBD) had been followed including six treatments and three replications which were; T 1 = soil test based 50% NPK with blanket dose, T 2 = soil test based 75% NPK with blanket dose, T 3 = soil test based 100% NPK with blanket dose, T 4 = soil test based 125% NPK with blanket dose, T 5 = local farmers practice (N 138 P 75 K 94 S 27 Zn 5 kgha -1 ), T 6 = control. The soil test based chemical fertilizers was N 115 P 30 K 75 S 20 Zn 3 B 1 kgha -1 . The hybrid variety of broccoli "Green Crown" was used for conducting the field experiment as planting material. Before sowing on the nursery bed, seeds treated by Thiram @ 2.5 g per kg of seeds. Healthy and appropriate age of seedlings (21 days) had been transplanted to the experimental plots of size 3 m  2 m at spacing of 50 cm  40 cm as per layout on the 20 th November 2019 during the first year and 16 th November 2020 during the second year. According to treatment, a TSP, Gypsum, Zinc sulphate (mono) and Boric acid had been used asbasal dose in the respective plots. Urea and MoP fertilizers were used as equal three splits at 15, 30 and 45 days after transplanting and mixed well with soil. Improved intercultural operations were done in all the experimental plots. The crop was irrigated and managed pests using biological methods meticulously. Broccoli curds were harvested before the buds opened on 29 January to 3 February 2020 during the first year and 24 to 29 January 2021 during the second year respectively. The observation associated with yield and its contributing characteristics (curd length and diameter, marketable curd weight (g), marketable yield ton per hectare were recorded taking five plants randomly from each experimental plot in each replication.

Design and methodology for shelf-life assessment of broccoli
To ascertain the shelf life for broccoli the following experimental design and methodology was followed as per the figure 1. The experiment was conducted in Completely Randomized Design (CRD) design, and it was carried out in triplicate. In the case of shelf life assessment of broccoli, treatment wise matured broccoli curd from each replication had been collected and placed in the selective storage materials (Low -Density Polyethylene (LDP; 35 micron) bag, High -Density Polyethylene (HDP;15 micron) vacuum pack, treated with 2% egg shell powder solution for five minutes, treated with 2% ascorbic acid solution for five minutes and control both at room temperature and cold storage condition. The change of curd color (just started to yellowing) was observed by eye estimation and to ascertain the shelf life of broccoli using each selective storage materials both at room temperature and cold storage condition.

Treatments
The recorded data of various characteristics were analyzed with the help of Statistical Tool for Agricultural Research (STAR) Program and the mean values of all the treatments had been adjudged by Tukeye's test at 5% level of probability for interpretation. Benefit Cost Ratio (BCR) for each treatment under investigation had been calculated based on the present market prices of inputs and outputs in order to find out the maximum profitable treatment.

Yield attributing characteristics and yield
The perusal of data in Table 1

Shelf life of broccoli using low -density polyethylene (LDP; 35 micron) bag
The perusal of data in Table 2 and 3 revealed that treatment T 1 (soil test based 50% dose of NPK with blanket dose) recorded maximum shelf life 5.35 and 5.75 days at room temperature (14-24 0 C with RH 60-65%) and 19.47 and 20.33 days at cold storage (4 0 C with RH 90-95%) condition and minimum shelf life 2.35 and 2.33 days at room temperature (14-24 0 C with RH 60-65%) and 12.34 and 12.73 days at cold storage (4 0 C with RH 90-95%) condition recorded in treatment T 4 (soil test based 125% NPK with blanket dose) using Low -Density Polyethylene (LDP; 35 micron) bag during the years of 2019-20 and 2020-21, respectively.

Shelf life of broccoli using high -density polyethylene (HDP; 15 micron) vacuum pack
The perusal of data in Table 2 and 3 revealed that treatment T 1 (soil test based 50% dose of NPK with blanket dose) recorded maximum shelf life 6.57 and, 6.83 days at room temperature (14-24 0 C with RH 60-65%) and 23.65 days, 24.25 days at cold storage (4 0 C with RH 90-95%) condition and minimum shelf life 3.38 days and 3.25 days at room temperature (14-24 0 C with RH 60-65%) and 15.25 and 14.25 days at cold storage (4 0 C with RH 90-95%) condition recorded in treatment T 4 (soil test based 125% NPK with blanket dose) using High -Density Polyethylene (HDP; 15 micron) vacuum pack during the years of 2019-20 and 2020-21, respectively.

Shelf life of broccoli when treated with 2% egg shell power solution
The perusal of data in Table 2 and 3 revealed that treatment T 1 (soil test based 50% dose of NPK with blanket dose) recorded maximum shelf life 3.53 and 3.67 days at room temperature (14-24 0 C with RH 60-65%) and 15.75 and 15.33 days at cold storage (4 0 C with RH 90-95%) condition and minimum shelf life 2.35 and 2.33 days at room temperature (14-24 0 C with RH 60-65%) and 12.34 and 12.73 days at cold storage (4 0 C with RH 90-95%) condition were recorded in treatment T 4 (soil test based 125% NPK with blanket dose) when broccoli was treated with 2% egg shell power solution during the years of 2019-20 and 2020-21, respectively.

Shelf life of broccoli when treated with 2% ascorbic acid solution
The perusal of data in Table 2 and 3 revealed that treatment T 1 (Soil test based 50% dose of NPK with blanket dose) recorded maximum shelf life 3.77 and 3.25 days at room temperature (14-24 0 C with RH 60-65%) and 14.25 and 15.50 days at cold storage (4 0 C with RH 90-95%) condition and minimum shelf life 1.85 and 1.75 days at room temperature (14-24 0 C with RH 60-65%) and 10.45 and 11.23 days at cold storage (4 0 C with RH 90-95%) condition were recorded in treatment T 4 (Soil test based 125% NPK with blanket dose) when broccoli was treated with 2% ascorbic acid solution during the years of 2019-20 and 2020-21, respectively.

Shelf life of broccoli in control
The perusal of data in Table 2 and 3 revealed that treatment T 1 (Soil test based 50% dose of NPK with blanket dose) recorded maximum shelf life 2.50 and 2.75 days at room temperature (14-24 0 C with RH 60-65%) and 13.37 and 13.53 days at cold storage (4 0 C with RH 90-95%) condition and minimum shelf life 1.57 and 1.55 days at room temperature (14-24 0 C with RH 60-65%) and 10.38 and 10.25 days at cold storage (4 0 C with RH 90-95%) condition at open place were recorded in treatment T 4 (Soil test based 125% NPK with blanket dose) during the years of 2019-20 and 2020-21, respectively.
Maximum shelf life in both the storage conditions usingHigh-Density Polyethylene (HDP; 15 micron) vacuum pack might be due to its sophisticated techniques which delayed and protected the physiological deterioration of broccoli curd.Within High-Density Polyethylene (HDP; 15 micron) vacuum pack having more control over the gas exchange with the surrounding air, the levels of CO 2 and O 2 around the produce might have further slowed down the conversion of starch to sugars. Curds stored in the cold conditions had maintained a greener color and at the same time no chilling injury symptoms, no decay incidence and no rot were observed there. In addition, storage at low temperature reduces the rate of respiration, and delayed senescence during storage of curds. Pre-harvest application of judicious inorganic sources of nutrients in broccoli production and better storage conditions along with appropriate use of scientific storage materials such as High-Density Polyethylene (HDP; 15 micron) vacuum pack might have protected the chlorophyll degradation and ethylene production. In addition, the said treatment also might have protected available moisture and minimize the rate of respiration along with strengthening the cell wall in the vegetative parts of broccoli which restricted the yellowing color and reduces weight loss. This might have maintained the shelf life and quality of broccoli. The findings of present investigation in respect of shelf life corroborate the findings of Jadhav et al. (2018) in broccoli.

Economic consideration
The perusal of data in Table 4 and 5 revealed that maximum gross return of BDT 394050 and 390300 ha -1 , maximum net return of BDT 286680 and 282382 ha -1 and Benefit Cost Ratio (BCR) with 3.67 and 3.62 were recorded in the treatment T 3 (soil test based 100% dose of NPK with blanket dose) in the year of 2019-20 and 2020-21, respectively.  Whereas, minimum gross return of BDT 123750 and 117450 ha -1 , minimum net return of BDT 35343 and 29592 ha -1 and Benefit Cost Ratio (BCR) with 1.40 and 1.34 were noted in T 6 (control) in the year of 2019-20 and 2020-21, respectively. The present findings indicate that treatment T 3 (soil test based 100% dose of NPK with blanket dose) was the maximum profitable treatment for broccoli production which could generate maximum net income with maximum Benefit Cost Ratio (BCR) as compared to other treatments. The results of present investigation corroborate the finding of Sharma et al. (2018) in broccoli.

CONCLUSION
Growers or entrepreneurs might have applied soil test based 100% dose of NPK with blanket dose for commercial purpose and 50% dose of NPK for consumption and getting anticipated quality attributes of broccoli. In addition, combined use of soil test based 50% dose of NPK along with High-Density Polyethylene (HDP; 15 micron) vacuum pack has been considered as an effective technology for maintaining the shelf life of broccoli both at room temperature (14-24 0 C with RH 60-65%) and at cold storage (4 0 C with RH 90-95%) condition.