Morphological and agronomic characterization of (Capsicum annuum L.) germplasm in Pakistan

The aim of the study was to estimate the magnitude of genetic variation through the characterization of germplasm using agronomical and morphological traits. In the current investigation 38 genotypes of chilli (Capsicum annuum) were evaluated at an agronomical and morphological level for (10 quantitative and 14 qualitative traits). A set of parameters covering different growth stages selected from the Capsicum descriptors developed by Biodiversity International Former. Qualitative traits were studied on a visual basis. Quantitative characters such as plant height ranged from 40 cm (36588) to 63 cm (36616). Fruit length and width range from 2.21 cm (36591) to 13.2 cm (36636) and 0.60 cm (36569) to 2.90 cm (36560 and 36441). Fruit weight varied from 0.85 g (36591) to 8.30 g (36651). Results obtained for yield/plant ranged from 175.49g (36652) to 780.3 g (36616). Results demonstrated the existence of diversity between the studied genotypes and consequently, providing the opportunity of attaining genetic advances in hybridization program for particular traits under consideration.


Introduction
Chilli peppers are used as vegetable and spices globally. It has been using since the beginning of civilizations. Bosland [1] reported that this ranked the chilli amongst the oldest cultivated crops of the Americas. According to Heiser [2] genus Capsicum is one of the first crop plants being grown in the New World with maize, beans and cucurbits. It is belonging to nightshade family Solanaceae, tribe Solanaceae, subtribe Capsicinae [3]. Most Capsicum species are 2n = 2x = 24. Some of the non-domesticated species are 2n = 2x = 32 [4]. The names of variety depending on type and location and the common names of pepper are chilli, red pepper, green bell or only pepper [5]. It is originated from South and Central America [6]. Mexico, as the centre of domestication and genetic diversity of Capsicum. It is considered as the first condiment to have been utilized by human beings and there is archaeological evidence of pepper and other fossil foods from as early as 6000 years ago [7]. The pungent varieties are generally named chilli pepper or simply "chilli". It plays very important role in commercial sector. Specially, it is used in cosmetics, pharmaceutical industries, and for oleoresin preparation. Chilli extensively grown for making powder is also harvested green. There are many nutritional, medicinal and economic benefits of its production. It is used for salad and as condiment also. It is used in foods for pungency and red colour. It is a small perennial shrub characterized by greenish-white corolla or white, more than one pedicel at a node having different fruit shapes and sizes [8]. Pepper grows relatively rapid with a maturity time of 3-4 months. It grown as an annual in the temperate region [9]. It grows on different types of soil but is most appropriate to welldrained loamy soils, rich in lime, with a pH of 5.5-6.8 and more water holding capacity. The optimum day temperatures for chilli pepper growth range from 20 to 30 °C [10]. It is often a cross-pollinated crop up to 63%. Pakistan is among the major chillies exporter and producer viz China, Mexico, Morocco and Turkey. In a global scenario, India is contributing (11 lac ton) 25 %. The global chilli production is approximately 7 million ton cultivated on 1.5 million hectares. Among top chilli producing and export countries, India exports 25%, China 24%, Spain 17%, Mexico 8%, Pakistan 7.2%, Morocco 7% and Turkey 5% are respectively. Badin, Mirpur khas and Umerkot, districts of Sindh represent the national clusters of red chillies production. A town of Kunri in Umerkot, contributes about 86% share in chilli production and is known as one of the leading production centers in Asia for red chillies [11]. Land of Pakistan blessed with varied types of climate and soil that grow various exogenous and indigenous medicinal plants, condiments, bearing plants and herbs. Regardless of the availability of the diverse agro-climatic conditions of the country, to produce the extensive range of plant species and as they were contributing in the national economy, by producing significant export earnings or import exchange [12]. Phenotypic characters such as plant height, fruit shape, fruit weight and flower colour have been used to differentiate genotypes of peppers and categorize them into groups [13]. Smith and Smith [14] reported that the use of phenotypic traits in categorizing and describing of germplasm is an important step in every characterization program. Morphological and conventional markers called descriptor used for identification of variety and genetic diversity in a plant. The aim of this study was to characterize germplasm using agronomical and morphological traits. This evaluation contributes to estimate the variability of the genotypes and also to determine promising materials appropriate for hybridization programs.

Materials and methods Material collection and site selection
This study was conducted at Bio-resources and Conservation Institute (BCI), National Agricultural Research Centre (NARC), Islamabad. The plant material comprised of about 38 genotypes of pepper including a check variety (P6). The germplasm was obtained from Bio-resources and Conservation Institute (BCI), National Agricultural Research Centre (NARC), Islamabad. Nursery of Capsicum was raised in greenhouse at NARC. The nursery was watered daily in the morning and evening till the seed was germinated. Care was taken to avoid too much watering to prevent lodging of seedlings. Field plants were transplanted after 35 days in a field in an augmented design with a plant to plant and row to row distance 45cm and 75cm respectively. The land was prepared by ploughing two times to level the field. Cultural practices and plant protection measurements were carried out when required raising a healthy crop. After transplanting, insecticide Lambda was sprayed on the plants to guard against the attack of tobacco caterpillar. Furadon was also used to control the cut warm.
A set of parameters covering different growth stages selected from the Capsicum descriptors developed by Biodiversity International former [15] for recording the data on agronomic traits. Information on the phenotype given by descriptors on morphological parameters is essential in giving accurate identification of species [3]. Ten plants of each genotype were selected randomly for data recording. Fourteen morphological (qualitative) traits were studied on a visual basis as shown in (Table  1). Data on the agronomical (quantitative) traits regarding Plant height (cm) of each pepper, plant was recorded. The 1 st fruit has begun to ripe. Mature leaf width (cm) and Leaf length (cm), leaf length was measure from base to the endpoint of the leaf whereas width was recorded at the widest point of the leaf, after maturity of the plant. Fruit width (cm) was measured at the widest point. Fruit length (cm) was recorded at the largest point. Fruit weight (g) was measured by weighing the fruits after picking. Fruit wall thickness (mm) was recorded at the second harvest at the point of maximum width. A number of locules was counted by cutting fruit at the broadest point. Fruit yield per plant (g) total fruit weight of each plant of each genotype was recorded.

Statistical analysis
Means were calculated through formula (∑ / ) for all quantitative traits. Standard error, mean, standard deviation, variance, the range was calculated through descriptive stat using Microsoft excel.

Results and discussion
Morphological characterization is a procedure, which requires a descriptive list, suggested by [16] to provide more information about gene pool preserved in gene banks and working collections. Morphological characterization is the only way of differentiation of genotypes on the basis of physical appearance. It is also very useful for bringing agronomically important traits, especially quantitative characters for improvement of the crop [17]. However it is also vital in genotypic identification, its application is greatly affected by prevailing environmental conditions and making the results locationspecific [17,18]. Smith and Smith [14] reported that the use of phenotypic traits in classifying and describing germplasm is rudimentary in any characterization program. All genotypes were characterized for different agro-morphological characters as shown in (Table 2). All parameters were measured in the laboratory and field at the usual harvest time.

Variability based of morphological traits
Data concerning morphology about 14 qualitative traits were estimated by the following data descriptor. Qualitative characteristics were determined on visual basis. According to the data descriptor all the qualitative traits are assigned with the code, data were recorded in the form of specific codes. All 38 genotypes showed (100 %) result regarding the annual life cycle, might be due to inherent characteristics. Data regarding to the stem colour, green colour (84. 21

Variability based on agronomic traits
The explanation of morphological character, variation is very significant in the commencement of programs intended with the selection of genotypes having quantitative characters like yield, fruit weight, length and width of fruit. Genetic variability evaluation includes mean and range which supports in the selection of genotypes as these designate characteristic of genotypes. Mean and range for 10 quantitative traits for all set of genotypes are given in (Table 3). The magnitude of variability existing in the genotypes was measured in terms of general mean, standard deviation, range and variance. It is important character for the selection purpose. (Fig. 1) (Fig. 1). The Capsicum genotypes displayed significant variability concerning fruit length, range of fruit length varied from 2.21 cm to 13.2 cm with the mean value 7.06±0.55. Maximum (13.2 cm) fruit length was observed in genotype 36636. Minimum (2.1 cm) fruit length was observed in 36591. Enough variation was seen in length and width of fruit is due to long and thin fruits wide fruits of chillies as shown in (Fig. 1)

Conclusion
Chilli is an essential cash crop, cultivated for spices and food all over the world. It is also used in medicines with lots of benefits to human health. Estimating unique genotypes in this study it was possible to find immense genetic variation at phenotypic level in Capsicum genotypes in climatic condition of Pakistan. We have selected 4 genotypes 36616, 36613, 36636 and 36560 on the basis of best performing morphological characters among whole set of genotypes characters These genotypes are potential source of genes for breeding programs for development of cultivar for food consumption.