Physicochemical evaluation of field pea (Pisum sativum L.) landraces under rainfed conditions of AJ&K-Pakistan

We investigated the physicochemical attributes of nine pea landraces collected from mountainous areas of Azad Jammu and Kashmir-Pakistan using one cultivar (Meteor) as control. Landraces were grown under the same agro-climatic conditions to remove variance caused by environment × genotype association. There was high physicochemical diversity among the landraces in the content of plant height (23.4-44.7cm), branches per plant(7.55-9.05), flowers/ plant(2-5.32), leaves per plant (31.53-32.80), seeds per pod (3.13-6.83), pods per plant (10.2-6.67), seed weight (g/100 seed) ( 22.80-23.93), pod length (4.50-8.16cm), total seed yield (10.30-9.99 kg/ha), pH (5.0-7.8), total protein content (10.76-20.23%), fiber content (0.76-7.20%), fat content(1.12-2.86%), carbohydrates (79.1-94.38 mg/g) and antioxidant activity (3.83-4.63%).Together, our results regarding the morphological and nutritional status of existing pea landraces will contribute and increase our knowledge about the field pea and broaden the gene pool available for future plant breeding programs.


Introduction
Pea (Pisum sativum L.) is one of the important winter crop belongs to family leguminosae, grown all over the world for fresh and processed forms.It is originated in the central or South East Asia.Pea is the world's third most significant legume grain after soybean and common beans [1].Pea is an excellent source of human diet, either eaten as vegetable and soup.Pea is rich source of protein, vitamins A, B and C and also contains a high proportion of minerals [2].In Pakistan, pea is an important crop, which plays a major role in farmer's economy.It is the most common crop and enjoys a great commercial demand due to its nutritive value.It is cultivated during winter in plains and during summer in highlands [2].In Pakistan, it is cultivated on an area of 10 thousand hectares with a total production of 72 thousand metric tons [3].Average yield per hectare of peas in Pakistan is quite low (7.2 t/ha) as compared to its potential and yield obtained in other countries [4].Pea with other legumes crops covers an area of approximately 1066 ha of crop areas in Azad Jammu and Kashmir (AJK)-Pakistan and is very vital food legume as compared with pulses grown in this area [5].As compared to many other countries, the average yield of pea crop is very low in Pakistan which may be attributed due to the non-adoption of improved varieties.Santalla et al. [6] have also reported that variation in old and unimproved varieties needed to determine in order to create valuable genetic variability for expansion of the narrow genetic base of profitable cultivars and for production of effectual use of resources.Cultivars perform different under different agro climatic conditions and various cultivars of same species grown in same environment often have yield differences.Unit yield and quality of crop is complex characteristics depending on organic arrangements between environment and heredity.The characteristics of a cultivar as well as combinations of traits differ according to climatic conditions of localities [7].Now a day, breeding techniques have progressed fastly as the need for high quality food has increased gradually.The initial step for crop genetic enhancement is the assessment of traditional genetic resources.It is need to imperative manage and save indigenous genetic resources, for the reason that they possibly contain valued alleles for crop enhancement.It is therefore needed to explore indigenous germplasm for physicochemical features and general quality [8].Keeping all these issues in view, present research work was designed to evaluate the available material for yield and other biochemical traits.Availability of genetic variability is vital for any breeding program which offers chance for choice of desired genotypes.Gupta et al. [9] have also reported about existence of considerable amount of genetic variability in pea.Based on our findings, high yielding disease resistant variety will be recommended for cultivation in the area and in addition to this future hybridization strategies will be designed.

Planting material and experimental design
Nine pea landraces were collected from different parts of mountainous areas of Azad Jammu and Kashmir-Pakistan.One commonly grown pea cultivars (Meteor) was comprised as control.All pea landraces and cultivar were sown on August 16, 2015, in well-prepared seed beds, using randomized complete block design (RCBD) with three replications.Research was led at the research area of the Department of Horticulture, University of the Poonch, Rawalakot AJK-Pakistan, which has a natural temperate climate (rainfed conditions).The size of plot was 6 m 2 with 15 cm line to line and 12 cm plant to plant dispersing with 18 plants in every line.Farm yard manure was applied @ 30 tons per hectare and NPK @ 120-75-50 kg per hectare.NPK was applied during the soil preparation.Nitrogen was applied in form of split doses.Whole plots were treated similar way, and followed by recommended agricultural practices.The material was harvested in December 28, 2015.

Determination of morphological parameters
Plant Height(cm), branches per plant, flowers per plant, leaves per plant, seeds per pod, pods per plant, seed weight (g/100 seed), pod length(cm) and total seed yield (kg/ha) were determined by using standard methods.

Determination of biochemical properties
Total protein content (%), pH, fiber content (%), fat content (%) and carbohydrates (mg/g) were determined according to standard methods of analysis [10].

Determination of antioxidant activity
The antioxidative potential from the seeds utilizing the DPPH (1,1-diphenyl-2picrylhydrazyl) radical was estimated.It was performed for half an hour after that adds DPPH (1,1-diphenyl-2-picrylhydrazyl).Measuring little vessel was kept in the darkness at normal temperature.Readings were taken at 517 nm.All determinations were carried out in triplicate.

Statistical analysis
Data were subjected to the analysis of variance (ANOVA) and tested for significant differences among treatments by the Least Significant Difference (LSD) test at (P ≤ 0.05) using MSTAT-C software.

Plant height (cm)
The analysis of variance exhibited that the 9 pea landraces varied significantly from one another with respect to plant height (Table 1).The most extreme plant height (44.7 cm) of pea was observed in cultivated variety while least plant height was found in Khaigala (23.4 cm).The plant height was shorter than past studies led at various areas, particularly fall sown plants [11].The reason of these distinctions can be credited to shorter developing period as an aftereffect of spring sowing.Since pea is a run of the mill cool season plant and its height increase under favorable, cool and moist conditions [12].Different responses to plant height might be due to genetic characteristic of cultivars and adaptability to a particular environment.The dwarf plant which could not benefit from prevailing climatic condition showed less adaptability in tested area.

Number of branches per plant
The statistical analysis indicated significant differences among pea's landraces regarding number of branches per plant (Table 1).Paniola accomplished maximum number of branches per plant (8.26) while the minimum numbers of branches were seen in Parat (7.55).More opportunity to blooming in a few genotypes with more number of branches means that more vegetative development because of climatic conditions.It was watched that a few genotypes had determinate sort development and their plant blossomed and depleted at the same time.The germplasm collected from different climatic circumstances, degree of adaptation may be measured the possible cause of difference.This variation could be due to genetic variability of different germplasms.Same results observed by Hussain and Badshah [13].

Number of flowers per plant
Results revealed that the highest numbers of flowers were seen in variety (5.32) while least quantities of flowers (2.00) were found in Pothi.Pea cultivars have an adequately extensive variety of term of vegetative period and their subsequent stages (blooming, development and so on) [14].

Number of leaves per plant
There was considerable diversity among the landraces for the number of leaves per plant (Table 1).The results exhibited that maximum numbers (32.8) of leaves per plant were noted in Bakh while minimum numbers (31.53) of leaves per plant were seen in Jandali.This variation could be due to genetic variability of diverse germplasms [13].

Number of seeds per pod
Maximum values for this parameter was recorded in variety (6.83).Range of minimum value was (3.13).The quantities of seeds per pod depend mostly on the species also on the natural environment.Numbers of seeds are correlated with pod length.Maximum pod length results in maximum number of seeds.The possible reason of less number of seeds per pod may be that environment was not suitable at the time of pollination and fertilization.Cool climate with moderate rainfall at the time of pollination and fertilization produced more number of seeds per pod as compared to dry climate and heavy rainfall at these stages [15].

Number of pods per plant
Greatest number of pods per plant were found in (10.2 cm) in variety, while minimum were observed in Trar (4.00 cm).Pods per plant decreased sharply because of warm climate during germination stage.Pea is sensitive to high temperature particularly during germination stage.More number of pods per plant may be due to small pod size as less nutrient are required for small pods compared with larger pods.Number of pods per plant relate to plant height.Vigorous varieties produced more pods while number of pods decreased with decrease in plant height, which might be attributed to genetic makeup of the plants.Pods

Antioxidant activity (%)
Significant difference among treatments for antioxidant activity results exhibiting significant difference for treatments were subjected to LSD test and are given in (Table 2) for their means.Mean values of antioxidant activity revealed that higher values were recorded in Paniola (4.63 %) and least value of antioxidant activity was (3.83 %) in variety.The antioxidant is mainly scavengers that reduce various free radicals and serving in avoidance of cellular injury and other injury.Pea's antioxidant has ability to produce resistance in tissues against diseases and stress conditions.A lot of antifungal molecules may encourage postharvest disease resistance such as phenolic compounds which take part in a binary role by acting as antifungal agents to enhance postharvest life and also as antioxidant to recover the quality during conservation of food products [22].

Correlation among trait
The relationships amongst the numerous traits are represented in (Table 3).Seed per plant was negatively correlated with branches per plant.Seed weight was negatively correlated with height of the plant.Pod length was significantly positively correlated with plant height and seed weight.Seed yield was positively correlated with seed weight, but negatively with pod length.pH was significantly positively associated height and pod length, however negatively with seed weight and seed yield.In the meantime, protein content was positively correlated with pod length and pH, however negatively correlated with seed weight and seed yield.Meanwhile, fiber content was significantly correlated with pod length and protein content, but negatively with seed yield.Fat content was significantly correlated with flowers per plant.As for carbohydrate content was significantly associated with seed weight and seed yield and negative correlation was seem with height, pod length, pH, protein and fiber content.Antioxidants were significantly positively correlation with height, pod length, pH, protein and fiber content, but negatively with seed weight, seed yield and carbohydrate content.Relationships between traits can flow from genetic linkage or pleiotropic consequence, but the environment can also play a great role.These environmental effects can impulsion a pair of traits whichever in the similar or in conflicting way [23].Therefore, at this phase, the associations we have stated must be realized as initial phase, till multilocation evaluation can display the comparative aids of environment and genes.

Table 1 .
Morphological characteristics of field pea landraces and cultivar (Meteor) per plant have significant and positive correlation with biological yield, grain yield and harvest index.Similar results have also been reported earlier.Some researchers observed number of pods per plant as the most useful yield component [4].

Table 3 . Trait correlations among physicochemical properties of field pea landraces and cultivar (Meteor).
Correlation is significant at 0.05 level; **Correlation is significant at 0.01 level *