Effect of Cropping and Management Techniques on Chilli (Capsicum annuum L.)  Production under Rain-Fed Farming

Rain-fed farming is the traditional approach to cultivation in most areas of the world. However, farmers practicing rain-fed farming are vulnerable to climatic fluctuations (Davendra, 2016). Chilli is an indispensable commercial crop grown extensively in sub/tropical regions Suresha et al., (2007). With rainfall of about 600 to 1250 millimeter (mm) chilli cultivation achieves exceptionally high yields (Akinbile and Yusoff, 2011). Chilli cultivation and production generally gives lower yields under rain-fed farming conditions than under irrigated conditions. For example, Indian dry chilli yield is between 0.2-0.4 metric tons (MT)/acre under rain-fed conditions and 0.6-1.0 MT/acre under irrigated conditions (Sharma et al., 2009). Under-watering drastically restricts plant growth and yield Ashrafuzzaman et al., (2011). In rain-fed areas with irregular, unpredictable or low rainfall, sustainable farming techniques including cropping systems and plant management methods are crucial for increasing the yield of any crops Sharma et al., (2009).
       
In Bhutan, chilli is grown in all the twenty districts. It is one of the important vegetables consumed by Bhutanese in various dishes (Ueda and Samdrup, 2009). The majority of growers depend on rain for chilli cultivation. Disease is a factor affecting chilli yields, with phytopthora blight being one of the major problems in chilli cultivation grown in rain fed conditions. To avoid such diseases, growers are recommended to grow chilli on raised beds of around 30 cm high to avoid water-logging and damp growing conditions. However, advice in a personal communication (Tshering, 12 March, 2016) indicated that raised beds can result in nutrients being lost due to rain splashing from the both sides of the bed. This is also a problem with overhead irrigation. Understanding of raised bed profiles such as height and surface structure, soil and water conditions, is necessary to improve production through effective farming techniques (Rana and Rana, 2011).
       
The structure of raised beds to increase potential yields, create better plant parameters and better soil water and chemical retention was the subject of the current research. Modifications proposed and tested included making a ridge on all four sides of the bed to avoid erosion by run-off during heavy rain or irrigation and to retain the nutrients and moisture in the soil. As well, management techniques were tested, such as removal of flowers/fruits also influences production, affecting the fruit size and composition due to source and sink relationships in rain-fed farming. Removing the first two flowers augment root development which later increase vegetative growth before fruit set. A strong root system with proper vegetative growth improves fruit bearing and fruit size (Maboko et al., 2012). Hence, removing the first few flowers play a vital role in quality and yield of chilli. This research included observation and practice of these management techniques.
       
The management factors such as improper cropping system, poor cultural management and poor soil conditionleading to low yield can be corrected using the right techniques, whereas, the abiotic factors such as rainfall, relative humidity and temperature cannot be brought under control until efficient structure is constructed. Therefore, this study was conducted to i) assess the growth and yield of chilli ii) to evaluate the soil moisture content and soil properties under different cropping and management techniques under rain-fed condition.

The experiment was conducted at Wookuna village, Punakha, Bhutan, from February to July, 2019.  A 2*2+1 (control) factorial experiment in complete randomized block design with three replications each was conducted. Each plot had the size of 1 meter (m) breath by 2 m length. Chilli seedlings were transplanted at plant to plant and row to row spacing of 30 and 60 cm respectively. The cropping levels included CL1.1 (a standard farmers style bed) CL 1.2 (a specially modified bed) and CL 1.3 (a standard farmers style bed with no flower removal) and management levels included ML 2.1 (1^st bottom three flower removal of chilli under a standard farmers style bed), ML 2.2 (1^st bottom three flower removal of chilli under a specially modified bed). A standard farmers style bed was the raised bed practiced by farmers. A specially modified bed was as same as a standard farmers style bed with a raised ridge (10 cm high by 10 cm width) at all four sides of the bed. Chilli variety, super solo was used. The cultural operations were based on chilli production guide (Berke et al., 2005). Mulching was done using compost but no irrigation was applied. 
       
Three plants per replication per treatment were randomly selected and tagged for the measurement of growth and yield parameters. Plant height, stem diameter, leaf length, leaf breadth and number of leaves were recorded 35, 50, 70 and 85 days after transplanting. Plant height was measured using measuring scale from the ground level till the last node of the plant. Stem diameter was measured using digital vernier caliper on the widest diameter of the stem. Leaf length was measured using measuring scale from the base of the leaf till tip, leaf breadth was measured using measuring scale based on the widest breadth and number of leaves were counted manually. Fruit weight, fruit length, fruit girth and fruit girth at the apex were measured during 2^nd harvest, whereas number of fruits per plant were counted from 1^st harvest until 3^rd harvest. Three fruits were randomly selected to record yield components. The fruit length was measured using measuring scale from base to apex, fruit girth and fruit girth at the apex were recorded using digital vernier caliper based on the widest girth around the base of fruit. Fruit weight was weighed using digital balance and number of fruits were counted manually.
       
Data on soil moisture was recorded by digital tensiometer once in every month until harvest. Two tensiometers were placed in separate treatments and recorded after an hour. This was mainly to compare soil moisture content among treatments. After harvest, soil samples of different treatments from two replications were collected. Soil samples were collected using the guide of TNUA (2013). The soil samples were analyzed at the laboratory of College of Natural Resources (CNR), Bhutan. Organic Carbon was determined by loss of ignition method, nitrogen by Kjeldahl method, Phosphorus by Bray 2 extraction molybdenum blue method and K by Ammonium acetate method by using Flame Photometer. 
       
Data was analyzed using statistix 23 (statistic package). The data was interpreted in excel sheet. Univariate and multivariate general linear models using Duncan test were used to find the significant difference (p=.05).

Growth parameters
 
The result showed that there was an effect of cropping (p<0.05) and management (p< 0.05) levels under rain-fed farming on all growth parameters. However, there was no interaction (p>0.05) between cropping and management levels. Among cropping levels, CL 1.2 performed the highest in plant height (12.56, 15.15, 29.49, 49.74 cm), stem diameter (2.83,3.36, 5.69, 8.98 mm), leaf length (3.83,4.69,8.18, 12.59 cm), leaf breadth (1.56,2.23, 3.03, 4.69 cm) at 35, 50, 70 and 85 days after transplanting (DAT). Only number of leaves per plant was found highest in CL1.1 throughout the growing season. Among management levels, ML 2.2 performed the highest in plant height (11.82, 14.42, 30.95, 48.62 cm), leaf length (3.60, 5.14,8.12, 11.69 cm) and leaf breadth (1.54, 2.12, 3.22, 4.52 cm), ML2.1 in stem diameter (2.77, 3.35, 5.84, 8.66 mm) and number of leaves per plant (13,16,67,141) at 35,50,70 85 DAT. CL1.3 performed the poorest in all growth parameters throughout the growing season. Among combination effect of cropping and management levels, CL1.2*ML2.2 showed the highest in plant height, plant diameter, leaf length, leaf breadth (Table 1, 2, 3, 4). Only leaf number was the highest under CL1.1*ML2.1 (Table 5). The lowest was performed under CL1.3*ML0 (control) in all the parameters.
 

 

 

 

 

       
The outperformed growth parameters of chilli in CL 1.2 could be due to high content of soil moisture (Table 7) in combination with soil properties enhancement in a modified bed (Table 8). Similar result is supported by Govaerts et al., (2007) that the soil moisture variability is associated with designing raised bed methods. According to Chadha (2019) soil moisture significantly attributed to growth parameters. Ghosh et al., (2018) further reported that soil moisture involves in nutrient transportation to roots and nutrient solution equilibrium. The growth parameters exhibited in ML 2.2 could be due combination of soil moisture with augmentation of NPK in modified bed in addition to concentrations enhancement of stored carbohydrates in stems, providing more leaf area and influencing plant size.  Similar finding was also figured by Sanchez et al., (1993) and Maboko et al., (2012).
 

 

 
Yield parameters
The data showed that there was an effect of cropping levels (p<0.05) on all yield components except fruit girth at the apex and fruit length (p>0.05). Similarly, there was an effect (p<0.05) of management levels on all fruit parameters except fruit girth at the apex. However, there was no interaction (p>0.05) between cropping and management levels on yield parameters. The result indicated that CL 1.2 showed the maximum in fruit weight (27.69 gm), fruit girth (27.48mm), fruit length with pedicel (21.11 cm), fruit length (16.36 cm) and fruit number per plant (27) except fruit girth at the apex (6.91 mm) was found the maximum in CL1.1.  CL 1.3 showed the minimum in fruit weight (19.24 gm), fruit girth (23.73 mm), girth at apex (6.55 mm), length with pedicel (18.56 cm), fruit length (14.46 cm) and fruit number/plant (10). ML1.1 recorded the maximum in fruit weight (26.76), fruit length with pedicel (21.41), fruit length (16.89), fruit girth at apex (7.02) and ML2.2 noted the maximum in fruit girth (27.22) and fruit number per plant (25). CL1.2*ML2.2 showed the maximum in fruit weight and number of fruits per plant whereas CL1.2*ML2.1 found the maximum in fruit girth, fruit girth at the apex and fruit length. TL1.3*0 observed the minimum in all yield parameters except minimum fruit girth at the apex which was found the minimum in TL1.2*2.2 (Table 6).
 

       
The maximum yield in CL1.2 could be due to high soil moisture content and soil properties content in a specially modified bed. The finding is similar to Singh et al., (2008) where the modified bed of ridged and furrow saves 20-25% water and increase 10-20% yield. The finding further supported by Bhardwaj et al., (2010) and Hamilton et al., (2005). The result stated by Sabeh, (2016) where beds were designed to add soil moisture and utilize nutrient availability was in line with Tshering’s (2016) statement. The fluctuation of yield in both ML2.1 and ML 2.2 could be due to fluctuation of moisture content in ML 2.1 and 2.2. Thus, finding showed that the 1^st bottom three flower removal of chilli had no effect on yield irrespective of different raised beds. However, number of fruit per plant (25) were found the maximum in ML2.2. This could be in accordance with Starkeayres (2014), who mentioned that removing first few flowers enhance quality and quantity. The similar finding supported Ryczkowski (2018) and Maboko et al., (2012) that removing flowers allow plants to allocate energy to root development and leaf growth that further produce uniform, quality and quantity fruits. Sanchez et al., (1993) further supported that removing few flowers from pepper plants increased fruit and seed yield. This study also found that even though CL1.2*ML2.2 performed highest in fruit weight and number of fruits per plant among the treatments, the yield was comparatively lower than elsewhere yield. The low yield could be  due to the fruit size of super-solo which  is larger than many varieties and the large size fruits are subjected to produce less numbers than the smaller size fruit. The similar result is reported (RNRRC- Annual report 1995-1996). It also could be, since this experiment applied only farm yard manure (FYM) and compost for mulching would have attributed to low yield, whereas, application of FYM with Suphala in farmers’ field every year would have attributed to high yield. Similar result is confirmed Dorji et al., (2011).
 
Soil moisture content
 
The finding found that there was a significant effect (p<0.05) of cropping levels of chilli on soil moisture whereas, there was no significant effect (p>0.05) of management levels on soil moisture throughout the growing period.  Similarly, there was an interaction (p<0.05) between cropping and management levels on soil moisture throughout the growing period. The result showed that CL 1.2 required less water (225.83, 227.83, 188.00, 105.33 mbar) from March till July, 2019, whereas CL1.3 required more water (261.67, 236.67, 225.00, 163.00 mbar). However, there was fluctuation of moisture content in ML1.1 (252.83, 224.67, 205.33, 154.67, 115.50) and ML1.2 (240.50, 262.33, 201.67, 151.67, 123.67) from March to July, 2019. The highest soil moisture content was observed in CL1.2*ML2.2 from March to July, 2019 (Table 7). The lowest soil moisture was found in TL1.1*2.2 till the mid-season and TL1.3*0 (control) in later growing stage. The high moisture content in CL1.2 could be due to prevention of water loss from the raised ridge side of a specially modified bed as stated by Tshering (2016).  This is in accordance with Govaerts et al., (2007) and Rossato et al., (2017).
 
Soil properties
 
The data indicated that there was significant effect of cropping and management levels on soil properties. However, there was no effect on interaction between cropping and management levels on all soil properties. CL 1.2 observed the highest in OC (0.64%), pH (6.22) and N (0.06%), P (0.44mg/I), K (1846kg/ha) and CL1.3 showed the lowest in OC (0.45%), pH (6.14), N (0.04%), P (0.31mg/I), K (1165kg/ha). ML2.2 performed the highest and ML2.1 observed the lowest in all soil properties. Similarly, CL1.2*ML2.2 found the highest and CL1.3*ML0 showed the lowest in all soil properties (Table 8). The highest content of chemical properties under specially modified bed could be due to nutrient and moisture retention within the bed which might have absorbed by plants for growth and yield of chilli crops as mentioned Ghosh et al., (2018). Similar finding was reported Miernicki et al., (2018). The finding by Buck (2019) observed that geometry bed reduced both run off water and nutrients. Waateringe and Geel (2016) highlighted that designing bed with climate change triggers moisture and nutrient.

Chilli farming in Bhutan is generally on a small scale, dominated by rain-fed farming resulting normally low yields due to unpredictable rainfall and management techniques. This study found that among the cropping techniques, chilli planted in a specially modified bed of a certain structure and surface topography in rain-fed farming outperformed the traditional growing bed styles in all aspects of plant growth, fruit yield, soil moisture content and maintenance of soil properties. Among management techniques, removal of the 1^st bottom three flower of chilli in a specially modified bed performed the best in all growth parameters, some yield traits and all the soil properties. Control plot, which represented the traditional plot structure, showed the poorest outcomes in all tested aspects.
       
It must be cautioned that a single season experiment is not sufficient to allow to recommend this approach in large scale cultivation and more research on different locations and soil types is needed to further substantiate the findings.
               
However, these results can be used immediately to assist in educating small-scale farmers in Bhutan in ways to improve their yields and therefore their incomes. We see no downside to this at all, only beneficial outcomes for the growers.