INFLUENCE OF PLANT POPULATION ON FRUIT AND SEED YIELD CHARACTERS OF CAYENNE PEPPER ( Capsicum frutescens L . ) GENOTYPES

This study assessed the influence of three plant populations (18518, 27777 and 40000 plants ha -1 ) on fruit and seed yield characters in 16 genotypes of Capsicum frutescens in 2010 and 2011 cropping years using a 3 x 16 split plot arrangement fitted into a randomized complete block design. Plant population and genotype formed main and sub-plots, respectively. Data collected on fruit and seed yield characters were subjected to analysis of variance after which means were separated using Fisher’s Least Significant Difference. Correlation analysis was also carried out among the characters. Significant and highest (P < 0.01) number of fruits per plant, single fruit weight, fruit weight per plant, number of seeds per fruit, 100 seed weight, seed weight per plant and seed weight per fruit were obtained under 18518 plants ha -1 while highest (P < 0.05) fruit yield ha -1 (11.3 tons) and seed yield ha -1 (698.7 kg) were obtained under 40000 plants ha -1 . Top fruit and seed yielding genotypes across the three plant population were PP9955-15 and Chilli 14, respectively. Number of fruits per plant showed negative and highly significant correlation with single fruit weight, fruit length, fruit width, number of seeds per fruit, 100-seed weight and seed weight per fruit. Significant positive or negative correlations were also observed among other characters. Plant population of 40,000 ha -1 using 50 x 50 cm spacing is recommended for high fruit and seed yield in C. frutescens production.


INTRODUCTION
A uniform distribution of plants per unit area is a prerequisite for yield stability (Diepenbrock, 2000).Studies on plant density for different types of pepper (Capsicum sp.) including bell, cayenne, pepperoncini and jalapeno have shown that plant density and plant arrangement can influence plant development, growth and the marketable yield of peppers (Khasmakhi-Sabet et al., 2009).Plant density is an important determinant of yield (per unit area) in most crops.Yield per unit area tends to increase as plant density increases up to a point and then declines (Akintoye et al., 2009).Norman (1992) recommended a spacing of 60 cm x 60 cm for bell pepper and 90 cm x 60 cm or 90 x 90 cm for hot pepper amounting to 27777, 18518 and 12345 plants ha -1 , respectively.Ado and Asiribo (1989) were reported by Adetula and Olakojo (2006) to have recommended 75 cm x 40 cm giving a population density of 33333 plants ha -1 for C. frutescens production.Berke et al. (2005) reported 1.5 m wide beds (furrow to furrow), 30 cm high, two rows per bed at 55 cm apart, with 45 cm between plants within rows, for a plant population density of 29,630 plants ha -1 .FAO (2004) observed that the spacing between the rows and within the rows in peppers will depend on the vigour and growth habit of individual varieties being grown.The wider spacing is commonly used where leaf, stem and fruit diseases are likely to occur (FAO, 2004).Unless planting on ridges or mounds, the young pepper seedlings are planted in rows five feet apart and three feet within the rows which translates to 150 cm x 90 cm (FAO, 2004).This spacing will provide a final plant stand of about 7,410 plants ha -1 while a spacing of four feet between the rows and three feet within the rows (120 cm x 91 cm) will give 8966 plants ha -1 .Plant spacing of 40 to 60 x 90 cm resulting in 27778 to 18519 plants ha -1 was recommended by FAO (2004) and Herman et al. (2011).Plant spacing of 60 x 60 cm has also been suggested by Herman et al. (2011) for hot pepper (Capsicum chinense Jacq.) production in Trinidad and Tobago.This implies that there is an opportunity to choose from wide range of spacing to use considering the Please cite as: Abdul-Rafiu A.M., Adebisi M.A., Daniel I.O., Bodunde J.G., Ajayi O.O., Muhammad S.M. and Dixon H.G. ( 2019).Influence of plant population on fruit and seed yield characters of cayenne pepper (Capsicum frutescens L.) genotypes.Agro-Science, 18 (1), 30-38.DOI: https://dx.doi.org/10.4314/as.v18i1.5 species to grow.Purpose of production may also influence plant spacing as closer spacings are favoured for production of fruits for canning.For example, George (2009) suggested 30-60 cm within rows and 45-90 cm between rows giving a range of 18,519 and 74,074 plants ha -1 respectively.In cover crops, highest leaf yield has been reported by Obalum et al. (2017) in fluted pumpkin planted at closer spacing of 25 cm × 25 cm.Also, Adubasim et al. (2017) obtained highest tuber yield in sweet potato planted at close spacing of 30 cm x 60 cm.Essentially, plant density plays a crucial role and contributes to the yield and marketable yield properties which in turn translate to economic returns.Literatures have shown that different planting spacing are being used while it has also been revealed that canopy size and plant morphology of the pepper species are different.There are also very few reports on seed yield and quality with regards to plant population in pepper.Similarly, information relating to planting population densities for seed production in unbedded (flat) field is relatively scarce.Therefore, there is need to determine which among these population densities will be most suitable and adoptable for higher yield in cayenne pepper especially for seed production under humid tropical conditions.Hence, this study was conducted to evaluate the effect of plant population densities on fruit and seed yield components in genotypes of cayenne pepper (C.frutescens).

MATERIALS AND METHODS
Seeds of 16 cayenne pepper genotypes were used for the study.The nursery was conducted at the screen house of the College of Plant Science and Crop Production, Federal University of Agriculture, Abeokuta (FUNAAB) while the field trial was conducted at the Teaching and Research Farm (FUNAAB) under rain-fed field conditions in 2010 and 2011 cropping years.Average rainfall during the period of the study was 600 mm and 335 mm for the two years respectively (rainfall data from the Dept of Agrometerology and Water Resources, FUNAAB).The study site is located between Latitude 7 o N 37ʹN, longitude 3 o 89ʹE and altitude of 210 m while the soil is loamy sand.Seeds of 16 genotypes of cayenne pepper were sown in the trays filled with sterilized topsoil.Two sowings were carried out to raise seedlings for the field evaluation which was carried out in two years.The first was between Jul. 18 and Aug. 26, 2010 and the second was between Jul. 29th and Sep.5th, 2011.The seedlings were monitored daily in the nursery and watering was carried out as required.Land preparation was carried out (mechanically) by ploughing twice with a space of two weeks between the first and second.Harrowing was carried out three days after the second ploughing.The field was laid out in a 3 x 16 splitplot fitted into randomized complete block design with three replications.Plant populations formed main plot while the genotype formed the sub-plot.The seedlings were transplanted at five weeks after sowing in both years under three plant populations; 40000 (using 50 x 50 cm spacing), 27777 (using 60 x 60 cm) and 18518 (using 90 x 60 cm) plants ha -1 .Each genotype, comprising three rows and a total of 24 plants per plot in each replicate.Weeding was done manually with hoes as urea and NPK fertilizers were applied in split doses to meet the nutrient requirement of 130 kg/ha N, 80 kg/ha P and 110 kg/ha K (Grubben and Tahir, 2004).

Data collection
Six plants in the middle row were selected for harvesting in each plot and data were collected on fruit and seed yield parameters which include: i.

Influence of Plant Population on Yield Characters of Cayenne Pepper Genotypes
Data Analysis Data collected were subjected to analysis of variance while significant means were separated using Fisher's Least Significant Difference at 5% level of probability.Pearson correlation co-efficient among fruit and seed yield characters were computed.

RESULTS
The effect of plant population density on the fruit and seed yield parameters evaluated across genotypes of cayenne pepper (C.frutescens) showed that number of fruits per plant, single fruit weight, fruit weight per plant, fruit length, number of seed per fruit, 100 seed weight, seed weight per plant and seed weight per fruit were significantly highest under 18518 plants ha -1 (60 x 90 cm) while similar values were recorded under 27777 plants ha -1 (60 x 60 cm) and 40000 plants ha -1 (50 x 50 cm) .In contrast, pepper plants grown under 40000 plants ha

Influence of Plant Population on Yield Characters of Cayenne Pepper Genotypes
The 100-seed weight of cayenne pepper genotypes under three plant densities (Table 5) shows that at 18518 plant ha -1 , PP0337-7562 had highest 100seed weight with 0.460 g closely followed by BG 4 (0.452 g), ICPN 19-07 (0.447 g) and PP0437-7509 (0.446 g) whereas Ata wewe recorded the lowest value of 0.324 g per 100 seed.The performance of the genotypes under 27,777 plant population density was similar to that under 18,518 plant density.The weight of 100 seed under 40000 plant population was significantly highest in PP0337-7562 (0.453 g) and this was closely followed by BG 4 (0.445 g), ICPN 19-01 (0.433 g) and PP0437-7509 (0.435 g) while Ata wewe still recorded the lowest value of 0.318 g.By comparing each genotype under the three plant population densities, significant variation was observed for eight genotypes.
The Pearson correlation coefficients (from the pooled data of two years) among fruit and seed yield characters in cayenne pepper genotypes (Table 6) showed that most of the characters had significant positive or negative correlation among themselves.The result indicated that number of fruits per plant showed negative and highly significant correlation with single fruit weight, fruit length, fruit width, number of seeds per fruit, 100seed weight and seed weight per fruit with coefficient values of between r -0.275 and r -0.449.In contrast, positive and highly significant correlation values were recorded between number of fruits per plant and seed weight per plant, seed production efficiency (SPE) and seed yield per hectare with coefficient values of between r -0.454 and 0.616 across the three plant population densities.Positive and highly significant correlation existed between single fruit weight and fruit weight per plant, fruit length, fruit width, fruit yield per hectare, number of seeds per fruit, 100-seed weight and seed weight per fruit while significant and negative correlation was observed between single fruit weight and SPE.It was also observed that fruit length and fruit width exhibited positive and significant relationship with fruit yield per hectare, number of seeds per fruit, 100-seed weight and seed weight per fruit but significant and negative correlation with SPE.Fruit yield per ha also correlated positively with other characters except SPE.

DISCUSSION
Maximum seed yield and quality are among the major objectives of successful seed production programme.In this study, cayenne pepper fruit and seed yield characters were significantly (P > 0.05) affected by plant population density and genotype.Therefore, consideration should be given to plant population density and genotype in seed production of cayenne pepper.Alam et al. (2011) have earlier reported that successful cultivation of any crop depends on several factors but sowing time and plant population are more important for the production system of different crops.Also, Adebisi et al. (2005) identified plant population as a cardinal role in determining seed yield.The significant effect of plant population on seed yield characters of the cayenne pepper showed that as plant population density increased from 18518 to 40000 plants per hectare, fruit yield per hectare increased from 5.52 to 11.32 tons ha -1 (105.1% increment) while seed yield per hectare increased significantly from 414 to 698.7 kg ha -1 (68.8 % increment).This shows that higher plant population density actually compensated for lower yield per plant and resulted in increased fruit and seed yield per area whereas bigger fruits did not compensate for fewer plants under low plant population as observed in the study.
On the other hand, all other fruit and seed yield characters such as fruit weight per plant, single fruit weight, number of seed per fruit, 100 seed weight, seed weight per plant and seed weight per fruit were significantly highest in cayenne pepper planted at low population density of 18518 plants ha -1 .Fruit width and seed production efficiency were not significantly affected by plant population.This is in contrast with the findings of Nerson (2002) who observed that seed yield index varied with plant population densities in muskmelon (Cucumis melo).This result suggests that increased fruit and seed yield on per-hectare basis is attributable to a higher plant population density but results in lower fruit and seed production per plant.The result conforms with the observations of De-Viloria et al., (2002) in bell pepper, Decoteau and Hatt Graham (1994) and Amnifard et al., (2010).Yahaya (2008) also observed that the performance of C. frutescens was enhanced by wider spacing as the number of fruits per plant and fruit size was reduced at closer spacing.
The result further showed that fruit length was longer although fewer and less robust in cayenne pepper planted at 40000 plants ha -1 .This could be due to pronounced competition among the plants.Therefore, plants at higher population are likely to be taller (with less branching) resulting in fewer longer fruits but higher cumulative number of fruits per area resulting in higher seed yield.Sanchez et al., (1993) reported that low plant densities resulted in larger plants that apparently transported photoassimilates from source leaves to sinks at higher rates than smaller plants in bell pepper.Ozer (2003) also observed from his study that summer rapeseed (Brasicca napus) grown at higher plant density produced higher seed yield compared to the lower population density.

Influence of Plant Population on Yield Characters of Cayenne Pepper Genotypes
The results of this study are similar to those reported for once-over hand-harvested cayenne pepper (Decoteau and Hatt Graham, 1994); multipleharvested bell pepper (Everett and Subramanya, 1983;Stofella and Bryan, 1988); and single machineharvested tabasco pepper (Sundstrom et al., 1984).Adebisi et al., (2005) also corroborated this in sesame with the genotypes performing better in seed yield at medium population density of 166, 667 plants ha -1 .The result further demonstrates that fruit and seed yield from 27777 plant population were generally lower compared to 40000 plant population per hectare.Therefore, increasing the plant population to 40000 plants still guarantees significant increase in fruit and seed yield per hectare.These findings are also corroborated by Nerson (2002) in Muskmelon who reported that high plant density produced high seed yield, mainly through the production of relatively numerous small fruits.Furthermore, it could be observed that the cayenne pepper genotypes also responded differently to plant population environments in terms of number of fruits, single fruit weight, 100 seed weight, seed yield per plant, fruit yield (t ha -1 ) and seed yield (t ha - 1 ).Yaldiz and Ozguven (2011) reported a fruit yield of 9.4 -24.4 t ha -1 in their study on yield and yield components of some Capsicum frutescens genotypes.Highest fresh fruit weight per plant (404.3g) in C. frutescens and lowest fresh fruit weight per plant of 18.9 g ha -1 were reported by Yaldiz and Ozguven (2011).A close observation of the seed yield characters among the 16 cayenne pepper genotype under the three plant population environments indicated that Ata wewe had the highest number of fruits which is probably due its small single fruit weight and 100 seed weight under the three plant population environments.The lowest number of fruits per plant recorded in IA108-3 under 40000 plant population probably implies that the genotype is suitable for cultivation under low densities while PP9955-15 responded negatively to low plant population as it recorded lowest number of fruits under 18518 and 27777 plant population density (48.33 and 51.67, respectively).PP9955-15 was the best in terms of single fruit weight which ultimately resulted in highest fruit yield per hectare under the three plant population densities.Although its fruits were not many but its big size could basically be responsible for the higher fruit yield recorded.Also, other top fruit yielding genotypes were PP0337 -7562, ICPN 19-07, PP0437 -7509 and Chilli 14.Also, 100 seed weight varied among the three plant population utilized in eight genotypes.This implies that variation observed was not due to chance.The best 100 seed weight was exhibited by PP0337-7562 (0.453 -0.461 g) while Chilli 14 showed the best seed yield per plant (29.14-34.05g) under the three plant population environments.Fruit and seed yield per hectare were also observed to be generally highest under the highest plant population (40000 plants per hectare) followed by 27777 plant population per ha in all the genotypes.Similar findings were reported by Adebisi (2004) in sesame and Nerson (2002) in muskmelon who stated that seed yield was highest in sesame at plant population of 166,667 per ha followed by 133, 3333 plants per ha in sesame while in muskmelon highest seed yield was obtained at 12 plants per m 2 (from 0.5 to 16 plant per m 2 ), although the fruits were relatively small but seed obtained showed best performance in terms of germination, emergence and vigour.
The relationship between the seed yield characters under different plant population densities showed that inverse relationship existed between number of fruits per plant and single fruit weight, fruit length, fruit width, number of seeds per fruit, 100 seed weight, and seed weight per fruit.By implication, the higher the number of fruits the smaller the single fruit weight as the plant cannot go beyond its fruit carrying capacity.The significant negative correlation between the number of seeds per fruit and number of fruits per plant, seed weight per fruit implies that the number of seeds per fruit reduces with increase in number of fruit per plant, 100 seed weight and seed weight per fruit.Nerson (2002) also observed that seed yield in musk melon increased with increase in fruit size due to increase in number of seeds, fruit and mean seed weight.Significant positive correlation was, however, observed between the number of fruit and seed yield per plant and seed production efficiency.The likely implication of this is that increased number of fruits per plant will translate to more seeds which eventually may increase seed weight per plant.Also, as the single fruit weight increases, the fruit weight per plant, fruit length, fruit width, fruit yield (t ha -1 ), number of seeds per fruit, 100 seed weight and seed weight per fruit are bound to increase.Increasing the single fruit weight consequently reduces seed production efficiency.This shows that more of the weight is concentrated in the fruit flesh rather than seed.It was also observed that the fruit weight per plant is a function of the fruit length, fruit width, 100 seed weight, seed weight per plant and seed weight per fruit.Genotypes and plant population were found to be major determinants of fruit and seed yield characters in cayenne pepper among other factors.Thus, increasing the plant population of cayenne pepper to 40,000 plants ha -1 resulted in highest fruit and seed yield.Quantitatively, fruit yield were increased by 105.1 and 4.24 % over 18518 plants ha -1 and 27777 plants ha -1 , respectively.Similarly, seed yields increased by 68.8 and 40 % over the recommended 18,518 and 27777 plants ha -1 , respectively.Genotypes PP9955-15 and Chilli 14 were identified as top yielding genotypes under the three plant population densities for fruit and seed yield respectively.A plant population of 40000 plants per hectare using 50 x 50 cm spacing is therefore recommended for cayenne pepper fruit and seed production.Investigation into the seed quality of cayenne pepper under the three plant population may also be necessary and therefore advocated.

Influence of Plant Population on Yield Characters of Cayenne Pepper Genotypes
Ata wewe with 0.321 g.Furthermore, seed weight per plant was highest in Chilli 14 with 31.26 g while NHV1A recorded the lowest value (11.48 g).On seed production efficiency (SPE), the highest was observed in Cayenne slim and Ata wewe with values of 13.9% and 12.8 %, respectively.
-1 had the longest fruit (8.64 cm) as well as highest fruit and seed yield per hectare (11.32 tons and 698.70 kg, respectively).The shortest fruits were observed on plants grown under 27777 plants ha -1 with 7.67 cm (Table1).Mean performance of fruit and seed yield characters of the 16 cayenne pepper genotypes across plant population density (Table2) revealed that Ata wewe was significantly highest in terms of number of fruits (207.83),followed by Cayenne slim (125.72) and Chilli 14 (100.39)while PP9955-15 (51.61) had the lowest number of fruits.Also, PP9955-15 had significantly largest single fruit weight (10.79 g) followed by PP0337-7562 (7.94 g) while the smallest was recorded in Ata wewe (1.07 g).Fruit weight per plant was largest in PP9955-15 with 565.8 g, followed by PP0437-7509 (480.6 g), ICPN19-07 (457.3 g) and PP0337-7562 (454.0 g).The lowest fruit weight per plant was observed in Sakarho, IA108-3 and Cayenne slim with 153.7, 154.9 and 185.9 g, respectively.For fruit length, ICPN 19 -07 and PP0437-7509 recorded significantly highest values with 12.80 cm and 12.38 cm, respectively while the lowest values were observed in Ata wewe (3.99 cm) and BG 4 (4.32 cm).Fruits of PP9955-15 and BG 3 recorded significant (P > 0.05) widest width of 2.38 and 2.23 cm, respectively whereas Ata wewe, Cayenne slim and Bird eye 11 recorded significant lowest while the lowest number of seed per fruit was observed in Ata wewe with 41.22.Genotype PP0337-7562 had the highest 100-seed weight (0.458 g) followed by BG 4 (0.448 g) whereas the lowest 100-seed weight was recorded in

Table 2 :
Mean performance of fruit and seed yield characters evaluated in 16 cayenne pepper genotypes across plant population density and cropping year

Table 1 :
Effect of plant population density on fruit and seed yield parameters evaluated across genotypes of cayenne pepper (C.frutescens)

Table 3 :
Fruit yield (ha -1 ) of 16 cayenne pepper genotypes evaluated under three plant population densities across two cropping years

Table 4 :
Seed yield (ha -1 ) of 16 cayenne pepper genotypes evaluated under three plant population densities across two cropping years

Table 5 :
Seed weight of 16 cayenne pepper genotypes evaluated under three plant population densities across two cropping years