INTRODUCTION
Broadleaf mustard [(Brassica juncea var. rugosa) (L.) Czern., 2n=36] is one of the most important leafy winter vegetables in Nepal. The production and yield of broadleaf mustard is 12,996 ha, 186,897 MT and 14.38 MT ha-1 respectively (MoALD, 2020). It is cultivated in wide range of agro-climatic conditions from Terai to high-hills in different season. It is frost tolerant leafy vegetable. In temperate region, the quality of leaves become better and tasty as compared to tropical conditions (Khatiwada et al., 1997). In the mid-hills, fresh leaves are widely consumed as vegetable. It is primarily produced for local market and local consumption. It is popular as green leafy vegetable because of its cheaper source of fiber, minerals and vitamins (Chalise et al., 2020). It is also consumed in the form of fermented product call ‘Gundruk’ in local language which is popular and favorite Nepal dish (Bhattarai et al., 2019). Nepal is rich in crop diversity which includes a large number of local leafy vegetable species (Regmi et al., 2004). It is locally called as Rayo. Some people called it as mustard greens (Rayo ko saag) which is one of the most common and popular winter vegetables grown in abundance from November throughout April. This plant grows quickly and thrives in chilly weather. Leaves are rich dark-green colors and a pungent mustard flavor with a biting taste. The greens are pungent and bitter only when eaten raw, but they become soft and delicious when cooked. The young tender leaves and long stalks taste best during colder weather, that is, fall, winter, spring. The greens can’t tolerate the summer heat and quickly develop seeds, becoming bitter and less tender. The leaves from the plants are harvested oneby- one as they mature; this allows the plants to continue producing. As the broadleaf mustard plants matures, it starts to form flowering shoots which is known as Duku (http://tasteofnepal.blogspot.com/2018/01/raayo-ko-saagmustard- greens.html).
Broadleaf mustard can be grown easily in low investment even in marginal lands (Khatiwada, 2008). Producing broadleaf mustard at farm yard manure heap around the yard of animal shed is very common in Nepal. Broadleaf mustard is highly preferred by most of the consumers owing to its pungent taste and delicious soft vegetable. In Nepal, high variations is found in broadleaf mustard gentoypes in terms of yield, leaf size, colour, leaf surface, leaf spreading, presence or absence of trichomes, taste (Chalise et al., 2020). Similarly, variation in growing season i.e. early and mid-season growing varieties are also available. Moreover, some varieties are suitable for Terai conditions and some are specific to mid-hill conditions. Paudel et al. (2016) reported that 58 different accessions of broadleaf mustard have been characterized and evaluated in National Agriculture Genetic Resource Center (NAGRC), Khumaltar, Lalitpur, Nepal.
In Nepal, there are four varieties released by National Seed Board (NSB) so far. These varieties are ‘Khumal Chauda Pat’, ‘Khumal Rato Pat, ‘Marpha Chauda Pat, and ‘Tankhuwa Rayo’ which have been cultivated since long time (SQCC, 2020). Recently a new variety and ‘Manakaman Rayo’ has been registered in the NCB and recommended for mid hills of western region (Adhikari et al., 2021). However, these varieties have wide range of growing conditions from Terai to high-hills, it is necessary to develop high yielding varieties. Therefore, this study was designed to evaluate the performance of different germplasms including two released broadleaf mustard varieties as check variety for the purpose of variety registration and release.
MATERIALS AND METHODS
The study was carried out in the field of National Horticultural Research Centre (NHRC), Khumaltar, Lalitpur during the winter season of 2019 and 2020. The experiment was laid out in Randomized Complete Block Design (RCBD) in 3 replications per treatment. Seven germplasms of broadleaf mustard namely ‘HRDBLM001’, ‘HRDBLM004’, ‘HRDBLM005’, ‘HRDBLM007’, HRDBLM009’, Marpha Chauda Pat, and ‘Khumal Chauda Pat’ were collected locally in farmers field and research stations under NARC and were evaluated. Seeds were sown in nursery bed on September and 28 days old seedlings were transplanted in 2.70 m2 experimental plot at 4530 cm spacing containing 20 plants per plot. Fertilizers and compost (farm yard manure) were applied at the rate of NPK = 200:180:80 kg and 20 MT ha-1 respectively. Whole dose of phosphorus and potash was applied as basal while one third nitrogenous fertilizer was applied at basal, one third top-dressed at 25 days and remaining one third top-dressed at 45 days of transplanting. Irrigation was given at weekly intervals and weeding was whenever necessary. Altogether four harvestings of the leaves were done after one month of transplanting.
Plant vigour
Vigour was recorded at maximum vegetative growth stage i.e. before second harvest using a 1 to 5 rating scale described by Gotame et al. (2019, 2021).
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1= Very week (all plants were small, few leaves, week plants, and light green colour)
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2 =Week (75% of the plants were small or all plants were shorter than normal plant height, plants have few leaves, and light green colour)
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3 = Medium, intermediate or normal growth
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4 = Vigorous (75% of the plants were taller than normal, robust with foliage of dark green colour, and leaves were well developed)
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5 = Very vigorous (all plants were taller than normal, ground completely covered by foliage, plants were robust, and abundant foliage of dark green colour)
Plant uniformity
Plant uniformity was recorded before first leaf harvest and before third harvest by using 1 to 5 points rating scale as follows; 1= very poor, 2 = poor, 3 = fair, 4 = good, 5 = excellent
Insect complex
Insect complex included aphids, white flies, beetles and leaf worms. The number of infested plants (plants showing symptoms) against the total number of plants per plot and population of insects on the leaf/plant were recorded. Aphids were the main insect found in broadleaf mustard field. The severity of insect population was measured by using the 1 to 5 rating score as follows; 1= Healthy (no infestation, no insect population), 2 = 30% plants and leaves infested, 3 = 60% plants and leaves infested, 4 = 80% plants and leaves infested, 5 = >80% plants infested in the plot.
Alternaria leaf spot
The symptoms were recorded based on 1 to 5 score. The number of infected plants (plants showing symptoms) against the total number of plants per plot were recorded as methods described by Gurung et al. (2020). 1= Healthy (no infection), 2 = 30% plants and leaves infected, 3 = 60% plants and leaves infected, 4 = 80% plants and leaves infected, 5 = >80% plants infected in the plot
Characteristics of leaf and leaf weight
Total number of leaves per plot, total leaf weight per plot (kg) and per plant (g) were recorded at each harvesting time. There were 4 harvestings of the green leaves. Number of leaf and leaf weight per plant was recorded in each harvest lot separately and cumulative numbers of leave were obtained by adding after the complete harvest.
Average leaf weight (g) was measured from randomly selected 20 marketable leaves per plot.
The weight was investigated two times, first one harvested from the 2nd lot and second one from the 4th lot.
Leaf length and width were measured in randomly selected 20 marketable leaves harvested at 2nd and 4th harvest lot.
Data analysis
The experimental data were processed by using MS Excel 2016 and analyzed by using GenStat var. 18.0 (Gen- Stat). Two-way ANOVA for F-test for RCBD design was used to analyze the differences between the means observed parameters (Gomez and Gomez, 1984). Normality was checked using histogram before analysis.
RESULTS AND DISCUSSION
Plant vigour and plant uniformity
Results on plant vigour was significantly different between germplasms (P<0.05) (Table 1). The mean vigour score showed that plants were more vigorous in ‘HRDBLM010’ and ‘Khumal Chauda Pat’ (4.7 in 1to 5 scale score). Plant uniformity was also significantly different between germplasms (P<0.05). Plant uniformity score showed that ‘HRDBLM010’ and ‘Khumal Chauda Pat’ were more uniform (4 in 1 to 5 rating scale). The phenotypic homogeneity of growth pattern refers to the plant uniformity.
Resistant to insects and Alternaria leaf spot disease
Results on insects was not significantly different between germplasms (P>0.05) (Table 1). However, the mean of resistant score to insects complex over the two consecutive season showed that ‘HRDBLM007’ was higher resistant to insects (1.8 in 1 to 5 scale score) followed by ‘HRDBLM001’ (1.9 in 1 to 5 scale). Resistant to Alternaria leaf spot was significantly different between germplasms (P<0.05) in 2020 but non-significant differences in 2019 (Table 1). The mean of leaf spot resistant over the two consecutive seasons showed that ‘HRDBLM001’ was more resistant (2.3 in 1 to 5 rating scale) as compared to other germplasms.
Characteristics of leaf
Leaf characters of seven broadleaf mustard germplasms were recorded in the winter season of 2020 and found that most of the characters were not significantly different between germplasms (P>0.05) (Table 2). But leaf weight was highly significantly different between germplasms. The highest leaf weight (65.1 g) was found in ‘HRDBLM010’ followed by ‘HRDBLM007’ (45.6 g) and ‘Khumal Chauda Pat’ (40.9 g) whereas the lowest leaf weight (23.5 g) was found in ‘HRDBLM001’. Chalise et al. (2020) reported that the highest leaf weight was produced by ‘HRDBLM003’ (61.50 g) followed by ‘Marpha Chauda Pat’ (58.47 g) at the mid-hills of Dailekh conditions. Our finding agrees with the finding of Chalise et al. (2020) to leaf weight.
Leaf length was not significant different between the germplasms. However, the longest leaf was recorded in ‘Marpha Chauda Pat’ (62.0 cm) followed by ‘HRDBLM010’ (41.4 cm) while the shortest leaf was found in ‘HRDBLM001’ (24.5 cm) which were statistically similar. Chalise et al. (2020) reported that the highest length was found in ‘HRDBLM003’ (51.56 cm) followed by ‘Khumal Chauda Pat’ (43.1 cm) at Dailekh conditions. Similar to leaf length, the leaf width was also observed non-significantly different between germplasms. The highest width of the leaf was found in ‘Marpha Chauda Pat’ (37.9 cm) followed by ‘HRDBLM010” (26.2 cm). The narrowest leaf width was found in ‘HRDBLM001’ (18.7 cm). Chalise et al. (2020) found that ‘Khumal Chauda Pat’ produced the widest leaf (23.93 cm) but it was at par with ‘HRDBLM007’.
Most of the germplasms have the similar petiole colour i.e. light green except ‘HRDBLM004’ which have greenish white petiole. The germplasm ‘HRDBLM004’ was the earliest bolting broadleaf mustard germplasm which bolted in 63 days after transplanting. Similarly, ‘HRDBLM007’ and ‘HRDBLM0010’ bolted in 68 days and 88 days after transplanting. Four germplasms ‘HRDBLM001’, HRDBLM009’, and check varieties ‘Marpha Chauda Pat’ and ‘Khumal Chauda Pat’ did not bolt even at the last harvest.
Leaf weight and leaf characteristics
The number of leaves per plant and leaf weight per plant showed highly significant difference between germplasms in two consecutive seasons (P<0.01) (Table 3). The mean of number of leaves per plant of two consecutive years revealed that the highest number of leaves was produced by ‘HRDBLM004’ (50 leaves per plant) followed by ‘HRDBLM007’ (36 leaves). The lowest leaves per plant was found in ‘Marpha Chauda Pat’ (17 leaves per plant). In both season of 2019 and 2020, ‘HRDBLM004’ produced the highest number of leaves (60, and 40 leaves respectively) which was followed by ‘HRDBLM007’ (43 and 30 leaves per plant respectively). The mean of leaf weight per plant of two consecutive seasons was the highest in ‘HRDBLM010’ (691.1 g per plant) followed by ‘HRDBLM004’ (535.4 g per plant) followed by ‘HRDBLM007’ (495 g per plant) respectively. In 2019 and 2020, the highest leaf weight was produced by ‘HRDBLM010 (780 g and 602 g per plant) followed by ‘HRDBLsM004’ (733 and 337.8 g per plant) and ‘HRDBLM007’ (610 and 380.0 g per plant). Yield per unit area is directly related to the number of leaf and leaf weight per plant i.e. higher the number of leaves, higher the leaf yield. Chalise et al. (2020) reported that highest leaf number (29.7) was produced by ‘HRDBLM005’ but at par with ‘HRDBLM007’ at mid-hills of Dailekh conditions.
The leaf weight per hectare was highly significantly different between germplasms in both consecutive seasons (P<0.01) (Table 4). The mean of leaf weight per hectare of two consecutive seasons revealed that the highest yield was found in ‘HRDBLM010’ (54.32 MT ha-1) which was followed by ‘HRDBLM004’ (44.28 MT ha-1). The lowest yield was found in ‘HRDBLM009’ (15.91 MT ha-1). In 2019 the highest yield was found in ‘HRDBLM010’ (57.78 MT ha-1) followed by ‘HRDBLM004’ (54.28 MT ha-1). In 2020 the highest yield was again recorded in ‘HRDBLM010’ (50.86 MT ha-1) followed by ‘HRDBLM007’ (38.10 MT ha-1). The finding of our research is in agreement with the finding of Chalise et al. (2020). They have been reported that ‘HRDBLM005’ produced the highest yield (39.78 MT ha-1) followed by ‘HRDBLM007’ at Dailekh conditions. It showed that the germplasm ‘HRDBLM010’ performed constantly better over the season. Adhilkari et al. (2021) found that ‘Manakamana’ variety was superior in terms of leaf weight (36.0 MT ha-1) followed by Mike Giant (25.8 MT ha-1) in Pokhara, Kaski (950 m asl) conditions.
The leaf weight is varied with germplasms x environment factors. Khatiwada (2008) reported about 31.0 MT ha-1 yield in ‘Marpha Chauda Pat’ of broadleaf mustard at Dhankuta conditions of Nepal. In another study, Khatiwada et al. (1997) reported that periodic harvesting in broadleaf mustard could be done up to six months after transplanting at Pakhribas, Dhankuta. However, in present study, the harvesting of quality leaf was done for 3 months after transplanting at Khumaltar, Lalitpur conditions.
CONCLUSION AND RECOMMENDATION
Among the seven germplasms ‘HRDBLM010’ was found to be higher yielder with larger sized leaf. It was noticed in the field that this germplasm was relatively resistant to drought, grew well and survived in low soil moisture conditions. The green leaf weight of ‘HRDBLM004’ though slightly lower than ‘HRDBLM010’, was also a promising germplasm. Similarly, ‘HRDBLM007’ was also another potential germplasm and found to be tasty and preferred by the consumer according to informal information from growers and market. Thus, these three germplasms showed superiority among the seven evaluated germplasms and could be recommended for cultivation at mid-hill condition of Nepal.
