VEGETOS: An International Journal of Plant ResearchOnline ISSN: 2229-4473
Print ISSN: 0970-4078

Research Article, Vegetos Vol: 30 Issue: 1

Quality Attributes of Broccoli – F1 as Affected by Different Planting Dates, Nutrient Levels and Spacings under Cold Arid Conditions of Ladakh (India)

Kunzang Lamo*, Kouser Parveen Wani and Shabir Hussain Khan
High Mountain Arid Agriculture Research Institute, Skuast-K, Leh (J&K), 194101, India
Corresponding author : Kunzang Lamo
High Mountain Arid Agriculture Research Institute, Skuast-K, Leh (J&K), India
Tel: 91-0194-2461258
E-mail: [email protected]
Received: November 23, 2016 Accepted: December 27, 2016 Published: December 29, 2016
Citation: Lamo K, Wani KP, Khan SH (2017) Quality Attributes of Broccoli – F1 as Affected by Different Planting Dates, Nutrient Levels and Spacings under Cold Arid Conditions of Ladakh (India). Vegetos 30:1. doi: 10.5958/2229-4473.2017.00004.0

Abstract

Quality Attributes of Broccoli – F1 as Affected by Different Planting Dates, Nutrient Levels and Spacings under Cold Arid Conditions of Ladakh (India)

The experiment was carried out at High Mountain Arid Agricultural Research Institute (HMAARI) Leh of SKUAST-Kashmir during Kharif 2014 and Kharif 2015 to assess the effect of different planting dates, fertilizer doses and spacings on head quality attributes of F1 broccoli ‘Fiesta’ under cold arid Ladakh conditions. The experiment was laid out in split plot design containing one main factor (planting dates i.e., 5th April, 16th April, 27th April) and two sub-factors (fertilizer doses viz., 60:80:40 kg/ha, 80:100:60 kg/ha, 100:120:80 kg/ha NPK and spacings viz., 60×45 cm, 45×45 cm and 60×30 cm) forming a total of 27 treatments each with three replications. Chlorophyll, total carotenoids and protein recorded significantly highest values in D1 F3 S1 (5th April, 100:120:80 kg/ha, 60×45 cm) while moisture content recorded highest in D2 F3 S1 (16th April, 100:120:80 kg/ha, 60×45 cm). TSS was significantly highest in D3 F3 S1 (27th April, 100:120:80 kg/ha, 60×45 cm) while vitamin C recorded maximum in D2 F1 S3 (16th April, 80:60:40 kg/ha, 60×30 cm)...

Keywords: Ladakh; Cold arid; Broccoli; Planting dates; Quality

Keywords

Ladakh; Cold arid; Broccoli; Planting dates; Quality

Introduction

Sprouting Broccoli (Brassica oleraceae L. var. italica Plenck) is one of the most important members of Cole group of brassicaceae family. Being highly nutritive, broccoli is most popular among the cole crops. This crop is rich in glucosinolates especially glucoraphanin, which is transformed by mirosinase enzyme into sulforaphane. This compound in broccoli or broccoli sprouts kills bacteria Helicobacter pylori responsible for most ulcers and stomach cancers. United States of America is the largest producer of broccoli in the world. In the global context, cauliflower and broccoli together is estimated to be cultivated in 120.426 million ha resulting a production of 21.2668 million tons with average yield of 17.65 tons/ha [1].
Ladakh, with unique geographical features presents good scope for broccoli production. The cool and dry environmental conditions of Ladakh provide optimum requirements for growth and quality of this crop. The cultivation of this exotic crop in this far flung secluded region of India has gained momentum in the recent years due to increasing demands from business enterprises thriving exclusively on tourism industry. Temperature no doubt plays the most crucial role in growth and development but nutrition is equally important. Quality of this crop is highly decided by both these factors. The recent changes in the weather pattern makes adoption of hybrids inevitable as open pollinated varieties are now more prone to anomalies. Till date, there has been no scientific research on this crop regarding planting dates and nutrition requirements and their effect on quality of the crop. So, considering the significance of a valid production package, an earnest attempt was made to critically examine the effect of planting dates, fertilizers doses and spacings on major quality attributes of broccoli (hybrid) under cold desert Ladakh conditions.

Materials and Methods

Two years experiment was carried out at High Mountain Arid Agricultural Research Institute (HMAARI) Leh of SKUAST-K situated on the left bank of river Indus at 3319 m amsl falling between 33058.551’ latitude and 77041.995’ longitude. Climate of the area is typically dry temperate with extreme fluctuations in the temperature. The seasonal condition comprises of moderate temperature and scanty rainfall and plenty of sunshine prevails during kharif season (May to August). Meteorological date of the area in respect of temperature for the cropping period has been given in Figure 1.
Figure 1: 2014 and 2015 temperature record.
The experiment aimed to study the response of broccoli in terms of quality to different planting dates, fertilizer doses and spacings under the cold desert conditions of Ladakh. Fiesta- F1 procured from the Bejo Sheetal Seeds Company, Jhalna, Maharashtra (India) was used in the study. Split plot design comprising of one main factor (dates of planting i.e., 5th April, 16th April, 27th April) and two sub-factors (fertilizer doses viz., 60:80:40 kg/ha, 80:100:60 kg/ha, 100:120:80 kg/ ha NPK and spacings viz., 60×45 cm, 45×45 cm and 60×30 cm) was adopted forming a total of 27 treatments each with three replications. Seeds were sown in trenches (covered with polythene) on the three planting dates and seedlings were hardened before uprooting and transplanted after about 45 days when they were ready. Each plot had an area of 2.4 m x 1.8 m (4.32 m2) accommodating 16, 20 and 24 plants. Five random plants from each plot were selected and data with respect to major quality parameters (exclusively of head) were collected and analyzed statistically as per standard statistical procedure given by Gomez and Gomez [2]. Levels of significance used for ‘F’ and‘t’ tests were p=0.05 as given by Fisher [3]. The dates presented in the following tables are the pooled values of both years (2014 and 2015) (Table 1a and 1b).
Table 1a: Effect of date of planting, fertilizer dose and spacing on head quality attributes of hybrid broccoli ‘Fiesta’.
Table 1b: Interaction effect of date of planting, fertilizer dose and spacing on head quality attributes of hybrid broccoli ‘Fiesta’.

Results and Discussions

Chlorophylls are plant pigment required for photosynthesis and both chlorophyll and carotenoids are light harvesting pigments with carotenoids having photo-protective roles. Illumination seems to affect chloroplast formation. As chlorophyll and carotenoids both exist within the chloroplast as chrophyll-carotenoid protein complexes, an increase in chloroplast means an increase in both the compounds. According to Simon et al. [4], climate has a major influence on the total carotenoid levels, the lowest levels corresponding to the lowest average temperature (10°C).The higher temperature range during harvest of D1 (5th May) crop ensured maximum carotenoids synthesis. As β-carotene is one of the major carotenoids present in broccoli, this carotene increases in cooler conditions during early growth stage.
Nitrogen is a constituent of chlorophyll molecule, phosphorous plays a role in stabilization of chlorophyll molecule and potash has its role in activation of enzymes responsible for photosynthesis and in translocation of carbohydrates. Therefore higher levels of inorganic fertilizers in F3 (100:120:80 kg/ha) aided chlorophyll synthesis. High doses of N, P2O5 and K2O increased the carotenoid content of spring sown carrots [5]. Moreover nitrogen is the main constituent of all amino acids in proteins and lipids that act as structural compounds of chloroplast [6,7]. Increased carotenoids content could be assigned to elevated levels of chlorophyll and associated light harvesting pigments. Application of inorganic nitrogen has been reported to improve carotene content in other crops such as Solanum nigrum [8], cabbage [9]. Nitrogen facilitates formation of chloroplasts which are rich in carotenoids [10]. Though carotenoids are nitrogen free, their synthesis is strongly inhibited during nitrogen deficiency. According to Krumbein et al. [11], enhanced nitrogen application increased the formation of carotenoids and chlorophylls. A positive relation between N fertilizer dose and carotene has also been reported by Sengewald [12] in spinach leaves and Kopsell et al. [13] in kale. Widest spacing in (60x45 cm) facilitated more nutrient availability and therefore more pigments content in plants. The overall lower levels of carotenoids could be due to the reduction in carotenoid synthesis with elevation.
Protein content directly depends on nitrogen. Nitrogen when multiplied by a factor of 6.25 gave total protein content. The uptake of nutrients is negligible in the early stages of growth. In fact about 60% of the nutrient uptake occurs in the last 3 weeks before harvest [14]. D1 (5th May) crop had warm soil temperature as they were harvested in 1st and 2nd week of August when the temperature was still optimum to affect nutrient uptake while in case of D2, the heads were harvested after 3rd week when the temperature had started dropping and therefore slow nutrient uptake might have occurred in comparison to D1 (5th May) as hydraulic conductance decreases as root temperature decreases. Also the heads of D1 (5th May) were harvested in peak summer, when the temperature was at its maximum peak. Transpirational losses due to heat stress might have necessitated more water uptake influencing nutrient absorption. Lower temperature conditions during D3 (27th April) might have restricted movement of soil nutrients. According to Korner [15], Low-temperature suppression of nutrient movement in soils and nutrient uptake by roots are well known phenomena. Protein content was maximum F3 in (100:120:80 kg) and S1 (60x45 cm) (60x45 cm). This could be due to more soil nutrient levels and their better availability. In a study by Kowalenko and Hall [16], high N rates significantly increased N in the leaf tissue and broccoli head without stimulation of the vegetative growth. Similarly widest spacing has least competition for nutrients. This ensures more nutrient availability per plant.
TSS is recorded maximum in D3 (27th April) and lowest in D1 (5th April). The reason might be exposure to cold stress during head development stage. Low temperature activates cold acclimation processes in plants, involving many biochemical and physiological changes, leading to enhanced tolerance to freezing [17]. Changes in levels of soluble sugars are often correlated to freezing tolerance for various plants [18]. Soluble sugars are key contributors to cold acclimation. Exposure of kale to low temperatures increases the content of soluble sugars [19].
Total soluble sugars (TSS) content of the marketable heads were maximum in F3 (100:120:80 kg/ha). Balanced application of NPK enhances the content of total soluble sugars. This might be due to the presence of better nutrients and phytohormones due to the application of NPK. Similar results have also been reported by Kumar et al. [20] in tomato. Results of the experiment revealed that the ascorbic acid content tended to be highest at low temperatures and the findings are in agreement with the results of Mahmud et al. [21], Lo Scalzo et al. [22], Schonhof et al. [23] who demonstrated higher levels of vitamin C in various Brassica vegetables grown under conditions characterized by lower temperatures. Being the northernmost region of India lying at altitude more than 2000 masl, Ladakh receives intense solar radiation round the year (due to thinner atmosphere, but temperature remains usually low and therefore often referred to as Cold Desert of India). This corroborates the findings of Lee and Kader [24] who reported increasing ascorbic acid at higher light intensities. This may be due to more glucose synthesis which is the prerequisite molecule for ascorbic acid synthesis. D1 (5th April) and D2 (16th April) are the periods of maximum light intensity but ascorbic acid is higher in D2 (16th April) due to lower temperature incidence as the heads of D2 (16th April) were matured and harvested from 3rd week of August on wards when the weather had become cooler. Higher vitamin C in broccoli at lower temperature has also been reported by Steindal et al. [25]. In D3 (27th April), cold stress resulted in higher vitamin C than D1 (5th April). The pool of ascorbate is low under normal growth conditions and increases under stress [26]. Singhal et al. [27] also reported an increase in ascorbic acid with delayed planting in broccoli. Higher N levels reduce ascorbic acid content. Therefore it read lowest in F3 (100:120:80 kg/ha) (100:120:80 kg/ha). The reduction in sucrose with increasing nitrogen fertilizer levels may be due to the role of nitrogen in increasing non sucrose substances such as proteins and alpha amino acid, and hence decreasing sucrose content leading to an increase in protein production and decreased carbohydrate formation since vitamin C production is tightly linked to carbohydrate metabolism [28,29]. The results confirm the findings of Lee and Kader [24] who reported a decrease in vitamin C with increasing fertilizer levels in many fruits and vegetables. Lowest competition in widest spacing (60x45 cm) resulted in highest accumulation of TSS and lowest vitamin C owing to more availability of nutrients.
Second date of planting D2 (16th April) recorded maximum moisture content and also the biggest heads. The more was the growth; the better was the water uptake and turgidity of plant. Also the heads were harvested in cooler weather conditions ensuring turgid heads. D3 recorded least moisture content because by the time heads of this planting date matured, temperature already dropped (September). This prevented water uptake and slowed growth. Higher temperature in 2014 seemed to favor more water uptake resulting in big sized turgid heads. This could be due to better nutrient uptake and utilization as a result of favourable environmental conditions. F3 (100:120:80 kg/ha) recorded maximum moisture content. Growth is favored by NPK. As it is well stated that nitrogen improves succulence and potassium plays significant role in water transport and turgidity. The lowest moisture content in F1 (60:80:40 kg/ha) might be due to inability to absorb adequate moisture from the soil due to lower general nutrition. The results corroborate the findings of Roni et al. [30] and Candido et al. [14] who reported maximum water content in heads supplied with maximum nitrogen in broccoli and cauliflower. Widest spacing in S1 (60×45 cm) recorded maximum water content which might be due to least competition among plants. Similar results were also reported by Roni et al. [30] in broccoli and Waseem and Nadim [31,32] in case of spinach.

Acknowledgement

The author thanks Dr. Kouser Parveen Wani and Dr. Shabir Hussain Khan for their suggestions and guidance all through this research.

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