EVALUATION OF NINETEEN BREEDING LINES OF EGGPLANT (SOLANUM MELONGENA) AND DIFFERENTIAL RESPONSE OF THE PROGENY (YALO X K3 BC2 P1) TO SPLIT APPLICATION OF NITROGEN FERTILIZER

ABSTRACT

The study to evaluate the variability of eggplant (Solanum melongena) cultivars for improved growth, yield performance and the response of a 6th generation progeny (Yalo X K3 Bc2 P1) to split application of nitrogen fertilizer was carried out at the Department of Crop Science, University of Nigeria, Nsukka Research and Teaching Farm between September, 2016 and August, 2017.  For the field trials, nineteen genotypes (five parents and fourteen progenies) were used while only one selected progeny (Yalo X K3  Bc2  P1) was used for the nitrogen trials. The field trials were laid in a randomized complete block design (RCBD) replicated three times while the nitrogen trials was a 2 x 4 Factorial Experiment laid out in RCBD replicated thrice. Factor A comprise the frequency of application of nitrogen (single and split application) while Factor B has 4 levels (0, 50, 100 and 150kgN/ha). Data were collected on plant  height  (cm),  Number of branches,  Number of leaves,    at  2,  4  and  6  weeks  after transplanting, number of fruit per plant, fruit weight per plant (g), number of fruit per plot, fruit weight per plot (g), fruit yield per hectare (t/ha) and fruit circumference. Statistical analysis showed that there were significant differences (p=0.05) in most of the data collected. The highest number of fruits per plot was seen in Ogbojioroke (1716) which is a local variety The highest fruit weight per plot was seen in K3 x Iyoyo Bc2P1 (1205g). Ogbojioroke also was found to be an early maturing genotype as it flowered and fruited at 57.7 and 65 days after sowing for nitrogen trials, Significant differences (p=0.05) were observed in both the flowering and yield data. Split application and 100kgN/ha gave the highest fruit yield per hectare of 12.33t/ha and 18.06t/ha respectively. Also the interaction between split application and 100kgN/ha gave the highest yield per hectare of 18.69t/ha. Split application was found to increase yield as well as stabilize yield as yields increased from first harvest (1628.07g) to second harvest (2072g) unlike in single application with 2050.68g and 1467g respectively.

INTRODUCTION

The Family Solanaceae  comprises about 2300  species, of which  almost one-half belong to the genus Solanum. Eggplant (Solanum melongena L.) is recognized as one of the most important members of the Solanaceae family which includes other economically important species like potato, tomato, tobacco and pepper (Doganlar et al., 2002; Knapp et al., 2013). Like tomato and pepper, eggplant is an autogamous diploid plant with 12 chromosomes (Sękara et al., 2007). Eggplant is believed to have originated in Asia, in the Indo-Burmese region (Isshiki et al., 1994; Hautea and Caguiat, 2014) but the most recent DNA sequencing studies suggested that eggplant arose from Africa (Li et al., 2010; Weese and  Bohs,  2010).  Most  eggplant  wild  relatives  are  from  Africa.  There  are  3  cultivated eggplant species: S. aethiopicum and S. macrocarpon, grown primarily in Africa, and the more  familiar  S.  melongena,  cultivated  worldwide.  S.  aethiopicum  is  a  fruit  and  leaf vegetable. It is a herbaceous shrub with hairy or glabrous leaves and hermaphroditic flowers, self or cross pollinated, single or in clusters. The fruits are consumed raw or cooked. They are light to dark green, white or blackish in colour, with a bitter taste that varies depending on saponin content. The fruit shape is round, elongated-round or oval with smooth or grooved surface and taste varying from sweet to bitter, particularly in the case of oval-fruit cultivars. At full maturity, the fruits turn red or reddish-orange due to high carotene content. Fruit surfaces vary from smooth to grooved or ribbed. The leaves are often consumed in the same way as spinach (Seek 1997; Macha 2005; Sękara et al., 2007). S. macrocarpon is grown for large, glabrous leaves (50 × 30 cm), used as a green vegetable. Fruits have large, often clasping calyx. They are sub spherical and large (3-10 cm in diameter, 2-6 cm long), cream white, green-white or green. Fruits are sweeter in taste (in comparison to S. aethiopicum), and most preferred. At full maturity fruits turn yellow, orange or brown with cracked surface (Bukenya 1994; Macha 2005; Sękara et al., 2007). S. melongena occurs in wild or semi wild form in India. Primitive eggplant characters are tall plants with large, spiny leaves, flowering in clusters with andromonoecy. Their fruits are small, green, and bitter in taste, with thick skin and hard flesh. Fruit colour varies from light to dark purple, almost black, green, or white. Fruit length is between 4-45 cm, and thickness 2-35 cm, at different shapes and weight ranging between 15-1500 g. The fruits are set as single or in clusters, up to 5 fruits. Physiologically ripe fruits become brown, red or yellow (Swarup 1995).

At present eggplant is the third most important crop from Solanaceae family after potato and tomato (Sekara et al., 2007). Greatest eggplant producers are China (17 million tons per year), India (8 million tons), Egypt (1 million tons) and Turkey (0.9 million ton) (FAOSTAT Data 2006). Eggplant varies considerably in several agronomic traits or characters. A wide variation has been observed in fruit shape, immature fruit colour, fruit size diameter of corolla, petiole length, branching habit, leaf blade, time of flowering, time of fruit maturity, fruit yield and taste (Blay, 1978; Chinedu et al., 2011). Assessment of variability present in eggplant species is an essential pre-requisite for formulating an effective breeding programme. Genetic variability as manifested in morphological and molecular diversity can be effectively used to develop more productive eggplant cultivars with improved agronomic traits.

Eggplant supplements starchy foods in addition to being good source of protein, minerals and vitamins (Lombin et al., 1988; Zenia et al., 2008; Agbo et al., 2012). As a biennial crop, Eggplant will require high quantity of nutrients to sustain its growth (Agbo et al., 2012) since both vegetative as well as reproductive phases of growth proceed simultaneously (Sharma and Brar, 2008). Hence, it becomes necessary to keep the plants supplied with nutrients throughout the growing period. These nutrients can easily be made available through the use of inorganic fertilizers (Agbo et al., 2012). N uptake depends on the quantity and quality of the N fertilizer, time and frequency of application, the crop grown and its duration, crop N-utilization efficiency, rooting depth, rainfall, soil hydraulic characteristics and management practices (Rasiah and Armour, 2001). Response to nutrients varies from 75 to 300 Kg Nitrogen, 30 to 224 Kg Phosphorus and 0 to 80 Kg Potassium per hectare (Sharma and Brar, 2008). This response varies across cultivars of Solanum melongena. Nitrogen, being a key nutrient in the physiology of the plant, improves the photosynthetic efficiency of the plant and ultimately the yield. However, research has shown that excessive application of Nitrogen fertilizer encourages prolonged vegetative growth at the detriment of the reproductive growth as the number of flowers declined when 200kgN/ha was applied as against 100kgN/ha (Umar and Momoh, 2015). However, research has shown that the period of application as well as the frequency of application determines plant’s response to N fertilization. Split applying crop nitrogen needs is a tool that is gaining widespread popularity among producers. In most cases, nitrogen fertilizer is the most costly major nutrient in any fertilizer program. By placing all the nitrogen requirements at seedling stage, a producer must rely on adequate rainfall during the growing season so the crop can efficiently utilize the nitrogen. According to Saskatchewan Soil Conservation Association, through split applying nitrogen to meet the changing demands of a growing crop, producers can potentially increase nitrogen use efficiency of their crop (SSCA, 2017). Split application reduces the exposure of nitrogen in saturated soils where the potential for losses such as leaching and denitrification are increased thus many producers view the technique as a risk management tool for dry land cropping, while other growers consider this practice as a way to manage plant nitrogen uptake more efficiently.

Thus the objectives of this study are:

i)   To evaluate growth and yield performance of the nineteen eggplant genotype.

ii)  To  determine  the  response  of  Solanum  melongena  L.  cv.  Yalo  x  K3Bc2P1   to application of Nitrogen fertilizer

iii) To determine the response of Solanum melongena L. cv. Yalo x K3Bc2P1 to frequency of application of Nitrogen.

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