Impact of Some Phytohormones on Chilli cv. CH- 27 (Capsicum annum L.)

Chilli (Capsicum annuum L.), 2n = 24, is an important annual and widely cultivated solanceous vegetable and spice crop in India and the world. India is the leading producer, consumer and exporting country of chilli crop. It was introduced from Peru (Patel et al., 2016) and from there it speeded to other parts of the world. Deep, loamy, fertile soil rich in organic matter and temperature ranging between 18 to 30°C, are considered ideal for satisfactory growth (Hazra et al., 2011). Mainly, it is a self-pollinated crop but a little percentage of cross pollination may occur also. The fresh and dried fruits of chilli contain phenolic acid compound “capsaicin”, in placenta which is responsible for the pungency in chilli. This pigment capsanthin also leads to bright red colour at the ripening stage of chilli fruit. Green chilies are supposed to be rich in vitamin A, C and the seed encompasses traces of starch. Besides this, fruits also contain vitamin A and carbohydrates. These are excellent sources of carotenoids, anti-oxidant, phenolic compounds which prevent cancer, diabetes, liver cirrhosis and cardiovascular diseases in the human body (Nwose, 2009). Many workers have revealed that the use of plant growth regulators showed a positive effect on productivity of chilli (Vandana and Verma, 2014). Singh et al., (2018) also concluded that the foliar application of various plant growth regulators like Kinetin, GA3 and NAA, positively impacted plant growth, development and seed yield traits such as plant height, primary branches, pods/plant, seeds/pod and 100-seed weight which led to increased growth, yield and quality parameters on garden pea variety (Pusa Pragati) under New Delhi climatic condition. Naphthalene acetic acid is one type of synthetic auxin, which plays an important role in stimulating cellular elongation in shoot, apical bud dominance, root initiation, control flowering, enhancement of growth and productivity. It is also involved in active cell division, cell amplification and cell elongation. flooding responses, enzyme induction and leaf and fruit senescence. Singh and Mukherjee (2000) revealed that different physiological and developmental processes, including plant vegetative growth, sex expression, yield and yield components in several vegetable crops, have been established to be influenced by foliar application of GA3. Rawat et al., (2002) also advocated that use of plant growth regulator has significantly increased the quality and yield of various vegetables. They proved that Napthalene Acetic Acid (NAA) is an important hormone, which tended to encourage the vegetative growth and increase yield of chilies. Results from Nazeer et al., (2020) in pea crop also indicated that pea cultivars can respond positively and favourably to growth, yield and quality attributes when plant growth regulators like NAA, GA3 and IAA, are applied. Thus, the present investigation was designed to find out the effects of plant growth regulators on chilli cultivar CH-27.

Experimental site and experimental materials
 
Present investigation was conducted at the Horticultural Farm of Lovely Professional University, Phagwara (situated in the central plain zone of Punjab state) during July 2019. The farm is situated at 31.240 and 75.701 latitude and longitude respectively and MSL is 252 meters. Maximum and minimum temperatures during the growing season were 42°C and 15°C respectively, whereas relative humidity varied between 60 to 85 per cent. The experimental material comprised chilli plants cv. CH- 27 along with two phytohormones (GA3 and NAA). Out of both phytohormones, different treatment of NAA was designed as T₁, T₂, T₃ and T₄ (sprayed @ 25, 50, 100 and 150 ppm, respectively) and GA3 treatment as T₅, T₆, T₇ and T₈ @ 25, 50, 100 and 125 ppm, respectively), while T9 was considered as control. 
 
The experimental layout and data analysis
 
The experiment was laid out in factorial RBD with 9 treatments and 3 replications. Total twelve qualitative and quantitative characters were accessed. Seeds of chilli cv. CH-27 were sown in protrays (coco peat + perlite + vermiculite) in polyhouse on 15/07/2019. Recommended/suggested cultural practices including and plant protection measures were followed (as per Punjab Agricultural University, Ludhiana). Immediately after sowing a light irrigation was given. Seedlings were transplanted in the main field after 35 days of sowing with spacing of 60 cm x 45 cm.
 
Data recorded
 
For recording plant height plant measuring tape was used from the ground level to the tip of the plant at 30, 60 and at last harvesting. Total no. of leaves per plant was recorded at 90 days after transplanting on the tagged plants and then average was calculated. The no. of branches per plant was recorded by taking actual counting at 30, 60 and 90 days after transplanting. It was also noted down when 50% flowers appeared in a particular plot. Fruit set (%) was worked out in relation to the number of flowers, originally present in labelled plants with the number of hermaphrodite flowers which set fruits. Plant spread, north to south and east to west was measured at 60-90 days after transplanting with the help of meter scale in centimeter and mean of the tagged plants were calculated.

Similarly, for calculation of average fruit weight (g), five fruits were randomly selected from the tagged plants in each replication and added and then average was calculated in grams. Length of fruit (cm)was calculated from the bottom to the tip of the fruit by using the vernier caliper from randomly selected fruit and their average was calculated in cm. For measurement of fruit diameter ‘same’ five fruits were used, measurement was taken at the widest portion of the fruit with a vernier caliper in centimeters. For recording yield per plant (g), fruits harvested and weight were recorded plant wise from every picking and in the last total yield per plant and express in gram. Similarly for Estimated yield per hectare (q/ha), harvested fruits were weighed (after each picking) and then they are divided with total area of the field plot and summed up. Ascorbic acid content of the fresh, randomly selected fruits was calculated by using 2, 6 Dichlorophenol indophenol dye titration method Aoac (1990). Capsaicin content of chilli fruit was calculated by adding 2 g of chilli powder into 20 ml methanol, after that this solution was placed in a water bath at a temperature of 60°C for 2 hours. After that it was removed from the water bath and cooled at room temperature.  At the rate of 5000 ppm for 5 minutes centrifugation of the sample was done. Supernatants were filtered and dilution was done using methanol. After that it was injected into the HPLC system at standard concentration. Calibration curve was prepared and SHU units were determined by coefficient corresponding to the heat value for pure capsaicin and corrected for sample extraction efficiency according to the formula: 18  x μg.g.

Table 1 reveals that maximum height of the plant was seen in T₄ at 30 days after transplanting (38.83 cm) while T₉ showed minimum height i.e., 25.84 cm. During 60 DAT and at the time of last harvesting maximum plant height was noted in T₅ i.e., 83.62 cm and 141.73 cm, respectively while control exhibited minimum i.e., 64.03 cm and 126.00 cm, respectively. Significant variations were found during the course of study. Above all, T₂ is statistically at par with T₇ at the time of last harvesting.  Maximum plant height was seen in T6 which may be due to the fact that GA3 may increase the movement of xyloglucan endotransglycosylase (XET) which has loosened the cell wall and enhanced cell permeability which in turn increases the plant height. Similar findings have been submitted by Sharma (2014) in brinjal and Merentoshi et al., (2016) in cucumber. 



Maximum plant spread was observed in T₂ followed by T₆ whereas minimum in control (T₉) (Table 1). Chilli plants spread inclined because auxin may expand photosynthetic metabolic rate and dry matter content. Results were found significant. Similar findings were contributed by Chandiniraj et al., (2016) in chilli.

Significant variations have been depicted from Table 1 and T4 exhibited maximum leaf number in chilli followed by T₃ whereas minimum in control (T₉). Maximum leaf per plant may be due to NAA that increased the cell elongation and multiplication of cells and ultimately resulted in plant development. Vegetative stage may have incited better developing conditions that resulted in higher no. of leaves per plant. A related effect of increase in growth due to application of NAA was also recorded by Kalshyam et al., (2012) in chilli.

It may be concluded from Table 1 that T8 increased the number of branches and followed by T₂ treatment whereas minimum was observed in T₉ i.e., control. Significant results were recorded. It is interesting to note that highly significant results were noted during 90 DAT.  It has been established that NAA plays a crucial role in numerous physiological processes, in turn inclined photosynthetic rate, respiration rate, transfer of compound viz, photosynthesis, respiration, energy store transfer, cell division and ultimately increased the branches of the chilli plant. This result was analogous with the result of Hilli et al., (2010).

At first, 50% flowers were observed in T₉ followed by T₈ whereas minimum in T₂ (table 1). Early blooming in NAA treatment may be because of its involvement in the change of vegetative apices to flower apices remained physiologically highly active to develop adequate food save for creating blossom. Moreover, results were also significant and research findings are matched with the earlier study of Hilli et al., (2010) in chilli.

Maximum fruit setting i.e., 55.1% was found T₃ followed by T₂ i.e., 54.3% whereas minimum in control (Table 1).  Similar findings were obtained in the study of Tapdiya et al., (2018) in chilli. Revanappa (1998) also advocated that GA3 and NAA reduces the flower drop because it inhibits the activity of cellulose and pectinase and reduces abscission production. They are also playing a major role in the development of ovaries during the seed filling process in chilli.

Fruit weight is an important criterion for determining yield. During study, it was recorded that fruit weight was increased in case of T₂ followed by T₆ (Table 2). Tiwari and Singh (2014) established that by application of auxin i.e., NAA it increases the average fruit weight. Maximum translocation of nutrients and increased photosynthesis increased the average fruit weight. Ultimately it maximizes the yield as well as acceptance by consumers.



It has been revealed in Table 2 that fruit length was increased in T₂ (9.03 cm).  Similar findings were obtained in the study of Tapdiya et al., (2018) in chilli while on the contrary, small fruit was recorded in control. NAA was an important plant growth regulator that increased the fruit length.  Increased cell number as well as cell elongation may be possible reasons for this increase.

Maximum yield per plant i.e., 567.06 g was found in T₂ (Table 2) and the minimum in control (352.00 g). NAA may be responsible for higher photosynthesis in plants ultimately which resulted in better root and shoot growth.

Maximum yield i.e., 152.89 q/ha was recorded in T₂ followed by T₆ whereas minimum in control (Table 2). Present study displays that plant growth regulators, particularly NAA@ 50 ppm (T₂) positively affected the yield per plant and yield per hectare. The improvement in yield related attributes may be due to the fact that NAA improves the physiology of plants and as a result, they become more active to make enough food to increase the flowers, fruit weight and yield characters. Moreover, such traits are responsible for increasing the yield of plants. Mahindre et al., (2018) also stated that application of 50 ppm NAA significantly increased all parameters of growth at later stages which in turn reflected higher fruit yield per hectare.

During study, ascorbic acid content of the fruit was significantly increased (85.64 mg/100 g) in case of T6 (82.58) (Table 3). Application of GA3 might help in synthesis of ascorbic acid and thereafter, it reduces the activity of enzyme ascorbic acid oxidase along with protection of the oxidation process of formed ascorbic acid. The results are in agreement with the findings of Chaudhary et al., (2006) in chilli.



Capsaicin, an important component of chilli responsible for pungency and irritant effect, is found highest (0.36) in treatment T7. Whereas the lowest value of capsaicin content (0.34) was found in treatment T₁, T₂, T₃ and T₉ (control) (Table 3).

From above studies may be concluded that application of NAA@ 50 ppm (T₂) had contributed significantly for increasing yield and yield contributing characters. Therefore, application of NAA@ 50 ppm may be recommended for chilli cultivation for field/commercial cultivation.