Performance of onion cv. Shah Alam for seed production under different NPK combinations
Muhammad Saleem Jilani, Kashif Waseem*, Faridullah, Muhammad Sohail Khan
Mehwish Kiran, Tehsin Ali Jilani and Saba Fatima.
Department of Horticulture, Faculty of Agriculture, Gomal University, Dera ismail Khan, Khyber Pakhtunkhwa, Pakistan.
Abstract
A field study was conducted to check the performance of onion cv. Shah Alam for seed production under different NPK combinations, at Agricultural Research Institute, Ratta Kulachi D.I.Khan, Khyber Pakhtunkhwa, Pakistan, during winter season 2012-13. The experiment was laid out in randomized complete block design (RCBD) with seven different NPK levels along with a control treatment. The treatments included T1= Control, T2= 30-20-00, T3= 60-40-15, T4=90-60-30, T5= 120-80-45, T6= 150-100-60, T7= 180-120-75 and T8= 210-160-90 NPK @ kg ha-1 and each treatment was replicated three times. The data on different parameters including days to sprouting, shoots per plant, leaf length, number of flowering stalks plant-1, length of flowering stalk, flowers per umbel, umbel diameter, 1000-seed weight, seed yield plot-1 and seed yield (kg ha-1) were collected and analyzed statistically. Results showed that all parameters were significantly affected by different combinations of NPK application except number of flowering stalks per plant. It was noticed that increment of fertilizer rates delayed sprouting but increased number of shoots per plant, leaf length, flowering stalks per plant, length of flowering stalks, flowers per umbel and umbel diameter in onion cv. Shah Alam. Thus, the highest doze of NPK (120-140-90 kg ha-1) excelled in almost all the parameters, as it took maximum days to sprouting (17.50), shoot per plant (6.48), longest leaves (41.20 cm), longest flowering stalk (67.10 cm), flowers per umbel (372.22), umbel diameter (6.45 cm), 1000 seed weight (3.03 g), seed yield per plot (378.0 g) and seed yield (420.0 kg ha-1).
Keywords: Onion, Allium cepa, Nitrogen, Phosphorus, Potassium, Flowering stalk, Umbel, seed weight, seed yield.
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Corresponding Author: Dr. Kashif Waseem, Assistant Professor, Department of Horticulture, Faculty of Agriculture, Gomal University, D.I.Khan, KPK. Pakistan.
Email . Cell # 03467869009
Introduction
Onion (Allium cepa L.) is one of the most important vegetable crop used for consumption in the raw and mature bulb stage (Mahanthesh et al., 2008). Among horticultural crops it is the second most important vegetable crop after tomatoes (Griffiths et al., 2002) and ranks first major exportation crop. It is appreciated by the people throughout the world due its distinctive flavor and medicinal properties (Padmini et al., 2007).
Onion is an integral part of our daily diet and it is commonly used in almost all food preparations (Hossain and Islam 1994). One of the advantages of onion is that the bulbs can be harvest and sold either green in salads (Lannoy, 2001), while the mature bulbs are cooked or eaten raw as a vegetable (Straub and Emmett, 1992). Onion contributes significant nutritional value to the human diet and has medicinal properties and is primarily consumed for their unique flavor or their ability to enhance the flavor to other foods (Randle, 2000). Its extensive use can cause shortage of this crop if optimum yield will not obtained as population of our country is increasing day by day. The two main causes of low yield are lack of improved production technologies and poor quality seed. Onion seed is usually produced in temperate and sub-tropical areas. It is a biennial crop for the purpose of seed production. Generally in first season bulbs are produced from seed and in the second season the selected bulbs are replanted to produce seed. Onion seeds have poor keeping quality and loose their viability within a year. Seed production program depends upon quality of seeds, agronomic practices and plant protection measures taken to produce healthy and vigorous crop. Among the agronomic practices, nutrient management through the use of fertilizers is considered as an important factor for seed production. Mineral fertilizers play an important role of onion plant growth and productivity (Devlin and Witham, 1986). The essential nutrients particularly, nitrogen, phosphorus and potassium (NPK) are necessary for plant growth, bulb yield, quality of bulbs and good quality seeds (Brewster, 1994).
Nitrogen is an essential element for both growth and productivity of all the plants and onion crops. The beneficial effect of nitrogen application on onion yield was noted by Mahmood et al., (2000), Tiwori et al., (2002), Devi et al., 2003 and Abdel-Mawgoud et al., (2005). Nitrogen is essential component of many bio-molecules, and is a part of number of enzymes and coenzymes associated with chlorophyll synthesis, photosynthesis and crop yield development (Don Eckert, 2010). Mishra (1994) reported that the application of 120 kg N ha-1 significantly increased the number of flowering scapes umbel size, seed yield and seed germination. Similarly, Phosphorus is also an important nutrient element that stimulates development of root, increase in the strength of stem, improve flower formation and seed production, earlier and uniform crop maturity, improved crop quality, and more resistance to plant diseases (Uwah et al., 2010). Bhardwaj (1991) found that seed production in onion was enhance by the application of 80 kg N ha-1 and 60 kg P2 O5 ha-1, which increased the number of scapes, size of the umbel, seeds per umbel and seed yield per plant. Potassium regulates the opening and closing of stomata during photosynthesis. It plays a vital role in protein synthesis and ionic balance. It is involved in the activation of enzymes and is essential for production of Adenosine Triphosphate (ATP) (Prajapati and Modi, 2012). Hence, for economic feasibility of onion a balanced ratio of primary macro-nutrients (NPK) is prerequisite for onion production. Deho et al., (2002) found that application of NPK @ 80-60-40 kg ha-1 produced more leaves and largest bulb size and gave the highest onion yield (kg ha-1). Several research workers (Patil et al., 1986 and Arian et al., 1997) have observed that the NPK fertilizers improved vegetative growth and yield of onions. Vegetative growth of onion plant, as well as its bulb quality and yield were increased with increasing the level of mineral fertilizers application (Desuki et al., 2006). Islam et al., (2007) also found that the application of 120:130:160 kg ha-1 NPK produced the maximum bulb yield in onion. Owing to the above mentioned facts, this research work was planned to determine the effect of variable rates of NPK on the quality and seed yield of onion (Allium cepa L) under the agro-climatic condition of Dera Ismail Khan.
MATERIALS AND METHODS
A field experiment was conducted to check the performance of onion cv. Shah Alam for seed production under different NPK combinations at Agriculture Research Institute (ARI) Ratta Kulachi, Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan, during 2012-13. The experiment was laid out in Randomized Complete Block Design (RCBD) with eight treatments replicated three times. Treatment sub plot size was kept 3x3 m2. The experimental area was thoroughly prepared by ploughing the soil three times. The medium size (3-5 cm) bulbs of cv. Shah Alam were planted on 25th October 2012 with row to row and plant to plant distance of 30 and 10 cm, respectively and seed crop was harvested on 13th June, 2013. All the required cultural practices were kept constant such as irrigation, weeding, pest and disease control etc. and given uniformly in all the experimental plots. The fertilizer treatments included were T1= Control, T2= 30-20-00, T3= 60-40-15, T4=90-60-30, T5= 120-80-45, T6= 150-100-60, T7= 180-120-75 and T8= 210-160-90 NPK @ kg ha-1. The parameters studied during this case of study were: days to sprouting, shoots plant-1, leaf length (cm), flowering stalks plant-1, length of flowering stalks (cm), flower umbel plant-1, umbel diameter (cm), 1000-seed weight (g), seed yield (g)/plot and seed yield (kg ha-1). All the data of all the above mentioned parameters were individually subjected to the analysis of various techniques (Steel et al., 1997), subsequently, then significant means were separated by the least significant difference test by using the MSTATC computer program.
RESULTS AND DISCUSSION
Days to Sprouting
Highly significant data was recorded regarding days to sprouting as affected by different dozes of NPK fertilizers in onion. The data shown in Table 1 clearly showed that increasing the rate of NPK had significantly delayed the sprouting as maximum days (17.50) were recorded in bulbs receiving the highest fertilizer dose (210-140-90 kg ha-1) closely followed by the plants receiving 180-120-75 kg ha-1 and 150-100-60 kg ha-1 NPK with 17.30 and 16.85 days, respectively and all these three treatments were statistically akin in terms of period taken for sprouting. Statistically similar results for days to sprouting were recorded in bulbs receiving NPK @ 120-80-45 and 90-60-30 kg ha-1 with 16.20 and 15.50 days, respectively. Whereas, control plots took minimum days (13.50) to sprouting closely followed by NPK@ 30–20–00 with 14.20 days to sprouting. The result showed that sprouting completion was progressively delayed with the increment of fertilizers levels. Our results resemble with the previous findings of Jilani (2004) who also reported significant differences in days to sprouting initiation and sprouting completion by the application of different levels of NPK fertilizers to different varieties of onion. Similarly Ali et al., (2007) also found significant differences in days taken for bulb emergence due to various rates of nitrogen and potassium application during seed production of onion.
Number of Shoots Plant-1
Significant variations existed in number of shoot plant-1 due to application of different rates of NPK fertilizers. Increment in NPK fertilizer doses also increased the number of shoot plant-1 as maximum shoot plant-1 were recorded in 210-140-90, 180-120-75, 150-100-60 and 120-80-45 kg NPK ha-1 with 6.48, 5.78, 5.13 and 5.00 shoots, respectively and all these treatments were statistically at par to each other. Statistically similar results were also obtained in 30-20-00, 60-40-15 and 90-60-30 kg NPK ha-1 with 4.45, 4.87 with 4.97 shoots plant-1, respectively. Whereas minimum shoots plant-1 (4.27) was recorded in control. These results are also in conformity with those of Khalid and Shedeed (2015) who reported that plant growth characters such as number of shoots per plant increased under various levels of NPK. Similarly, Desuki et al., (2006) also reported an increase in Onion vegetative growth with an increase in mineral fertilizer application.
Leaf Length (cm)
A progressive increment (cm) in leaf length was noticed with an increase in fertilizer rates. Significant variation existed in leaf length among the treatments, as shown in Table 1. The maximum leaf length (41.20 cm) was reported in 210-140-90 followed by 180-120-75 and 150-100-60 with 39.00 and 38.15 cm long leaves, respectively. Intermediate results were found for 120-80-45 and 90-60-30 kg NPK ha-1 with 37.00 and 35.60 cm long leaves, respectively. The shortest leaves (29.75 cm) were found in plants growing in control which differed significantly from all other treatments. The result showed that leaf length (cm) increased when higher doses of NPK were applied. The reason that control failed to yield more leaf length might be due to the non-availability of nutrients in the medium as compared to the other media, used. These results are in agreement with the work of Jilani (2004) who also reported significantly longest leaves by application of different doses of NPK to various cultivars of onion. Pandey et al., (2012) also reported increased leaf length with increasing rates of NPK.
Flowering Stalks Plant-1
Although no significant variation was observed among the treatments yet numerically fertilizers application increased the number of flowering stalks plant-1 and maximum number of flowering stalks (19.40) was recorded in plants getting the highest NPK doses. The un-fertilized plants and plants receiving lower doses of NPK fertilizers possessed the lowest number of flowering stalks plant -1. It was reported by Hanna-alla et al., (1991) that fertilizers application did not affect this trait as it is genetic character. These results are also in affirmation with Yaso et al., (2007) who found almost similar results for number flower stalks plant-1 as affected by different NPK combinations.
Length of Flowering Stalks (cm)
The perusal of data revealed that fertilizers application increased the length of flowering stalks. The longest flowering stalk (67.10 cm) were noticed in highest NPK doses (210-140-90) closely followed by 180-120-75 kg NPK ha-1 with 65.93 cm long flowering stalks and both treatments produced statistically similar length, as shown in table 1. All other treatments produced statistically similar results for length of flowering stalks including control. The enhancement of length of flowering stalks with the application of different rates of NPK fertilizers indicated that adequate supply of macro nutrients improved flower characteristics of onion cv Shah Alam under the agro-climatic condition of D.I.Khan. Our results are supported by the findings of Jilani (2004) who also reported longer flowering stalks by application of different doses of NPK fertilizers to different varieties of onion.
Number of Flowers Umbel-1
Significant variations existed in number of flowers umbel-1 due to application of different rates of NPK fertilizers. The results showed an increased number of flowers per umbel with increased rates of NPK, as maximum flowers umbel-1 (372.22) was recorded in plants receiving the highest rates of NPK (210-140-90) followed by 180-120-75 kg NPK ha-1 producing 366.22 flowers umbel-1 and both treatments were statistically alike. Statistically similar response for flowers umbel-1 was found in 120-80-45 and 90-60-30 with 315.70 and 302.50 flowers umbel-1, respectively. The minimum number of flowers umbel-1 (266.61) was observed in un-fertilized plants which differed significantly from all other treatments except (30-20-00) which produced 278.20 flowers umbel-1. Similar findings have been reported by Ali et al., (2007) who recorded greater number of flowers umbel-1 by application of different doses of N and K.
Umbel Diameter (cm)
Significant variations existed in umbel diameter due to application of different rates of NPK fertilizers. An increased rate of NPK fertilizer rate (210-140-90) produced maximum umbel diameter (6.45 cm) which differed significantly from all other treatments. It was followed by 150-100-60, 180-120-75, 120-80-45 and 90-60-30 kg NPK ha-1 with 588, 5.87, 5.65 and 5.54 cm umber diameter and all these treatments were significantly similar. The un-fertilized plants produced minimum umbel diameter (4.35 cm) which also differed statistically from other treatments. Statistically similar umbel diameter of 4.92 and 4.96 cm were recorded in 30-20-00 and 60-40-30 accordingly. Our results resemble with the previous findings of Bhardwaj (1991) who also found increased onion umbel diameter with increased fertilizer applications. Likewise Ali et al., (2007) also recorded greater umbel diameter, highest number of fruits set per umbel and maximum percentage of fruits set per umbel by application of different doses of N and K.