黑料网

Adaptability; Lettuce; Location; Variety; YieldS

Introduction

Lettuce (Lactuca sativa L.) is one of the most popular salad crops in the group of leafy vegetables with the largest production area coverage among salad crops in the world (Luchia et al., 2018). The genus Lactuca L. is an annual leafy herb belongs to the family Asteraceae (Compositae), the largest of the dicotyledonous families (Funk et al., 2005).

Lettuce is native to the Mediterranean area and Asia Minor, while it was domesticated in the shores of Egypt around 4500 B.C. (Rubatzky & Yamaguchi, 2012). However, the greatest species diversity can be found in the Mediterranean basin and Southwest Asia (Lebeda et al., 2009). Lettuce is produced commercially in many countries and is also widely grown as a vegetable in home gardens (Kristkova et al., 2008). The main producers of lettuce in the world are the USA, Spain, Italy, Japan and, France (Januka et al., 2021) [1].

Lettuce can grow in a variety of soil types and climatic conditions. However, it is extremely sensitive to drought due to shallow root system. It is best grown in silt loams and sandy soils as these soil types provide better drainage and warm up more readily during the day, which is especially important during cooler periods of the growing season (Kristkova et al., 2008). Lettuce is ranked 26th among vegetables and fruits in terms of nutritive value and 4th in terms of Consumption (Tiru et al., 2018).

Lettuce is rich in vitamin A and minerals like calcium and iron. It also contains protein, carbohydrate and vitamin C. In 100 g of edible portion of lettuce contains 93.4 g moisture, 2.1 g protein, 0.3 g fat, 1.2 g minerals, 0.5 g fiber, 2.5 g carbohydrates, 310 mg calcium, 80 mg phosphorus, 2.6 mg iron, 1650 I.U. vitamin A, 0.09 mg thiamine, 0.13 mg riboflavin and about 10.0 mg vitamin C (Gopalan and Balaraman, 1966). Also, the nutritional components in lettuce are associated with the reduction in the risk of cardiovascular diseases and certain cancers (Hung et al., 2004; Chan, 2011) [2].

Lettuce is one of the major leafy vegetable crops produced for local consumption in Ethiopia. It is extensively grown in most parts of Ethiopia on diverse ecology (Tiru et al., 2018). Farmers of Fogera and Libokemkem also produced unknown low yielder and diseases susceptible lettuce cultivars. The demand of lettuce is also gradually increasing but relatively only a few farmers are involved with a little lettuce crop production due to the lack of high-yielding and good quality cultivars. There is no investigations have been done so far to improve production and productivity of lettuce in the study areas. In this area, farmers need diseases resistant adaptable high yielder lettuce variety. Hence, identification of adaptable high yielder lettuce varieties is highly important for the study areas. Therefore, the major objective of this study was to identify adaptable high yielder improved lettuce variety/ies and recommended a suitable one for farmers of Fogera and Libokemkem districts in Northwestern Ethiopia and areas of similar agro-ecologies.

Materials and Methods

Description of the study area

Field experiment was conducted in the North-Western part of Ethiopia at farmer’s land of Libokemkem district from June to September in 2020 and at research station of Fogera National Rice Research and Training Center (FNRRTC) from June to September in 2020 and 2021 under rain-fed condition. Experimental site at Libokemikem is found at 12 o 08’N and 37 o75’ E with altitude of 1844 m above sea level. Whereas, FNRRTC is located at 11°58’ N, 37° 41’ E and at 1810 m above sea level in Amhara Regional state, Ethiopia. According to the average meteorological data, the annual rainfall, average air temperatures and soil type of Libokemkem(1200 mm,19.5°C and clay loam) whereas Fogera (1300 mm,18.3°C and black Vertisol) respectively (Dejen et al., 2021, Gezahegn,2022) [3].

Experimental material and experimental design

Tesfa and RSK-3 lettuce varieties obtained from Holeta Agricultural Research Center were used in this study. The experiment was laid out in a randomized complete block design with three replications at Fogera and Libokemkem districts. Spacing of 30 cm between plants and 40 cm between rows were used with plot size of 3 m length and 3.2 m width. The path between blocks and plots were 1 m and 0.5 m, respectively. Seeds were sown on nursery bed at FNRRTC research station and seedlings at 5-6 leaf stages were transplanted on the selected research field of Fogera and Libokemkem district. Dead plants were replaced within a week after transplanting. All other crop management practices were applied uniformly as recommended for the crop [4].

Data collection

Growth and yield parameters were collected at research field by sampling five randomly selected plants from central six rows of each plot. Data on stand count at harvest, plant height, leaf number, leaf length, leaf width, head-diameter and fresh vegetative yield were recorded [5].

Statistical analysis

The average of the collected data were subjected to analysis of variance (ANOVA) to evaluate the difference of varieties, the varieties response to different locations and their interaction effect as the procedures stated for randomized block design by Gomez and Gomez (1984) using Statistical Analysis System (SAS) version 9 software package and least significant difference (LSD) was used to separate means at 0.05 and 0.01 probability levels of significance (SAS, 2002) [6].

Result and Discussions

Analysis of Variance

The analysis of variance for yield and other agronomic characters is presented in Table 1. All studied traits showed a significant difference between locations. Leaf width showed a significant difference between varieties. However, there is no significant difference between the varieties on the remaining growth and yield component parameters. And also, there is no significant difference between varieties with locations interactions [7].

Table1: Combined analysis of variance for yield and yield related traits of lettuce varieties tested on two locations (Fogera and Libokemikem) at rain-fed condition in 2020.

Mean performance of lettuce varieties for yield and yield attributed characters

Plant height is the main factors in determining the yield performance of lettuce. Plant height ranged from 21.28 cm to 32.78 cm with a mean of 26.7 cm. The analysis of variance showed that location had significance influence on plant height. Significantly higher (32.78 cm) plant height was obtained at RSK-3 variety from Libokmekem district. While, significantly lower (21.28 cm) plant height was obtained from tesfa variety at Fogera site. According to Lita (2022) measured plant height of lettuce at 30 days from transplanting and obtained mean value of 18.52 cm. The analysis of variance revealed that there was significant difference (P<0.01) between locations on head diameter of lettuce varieties. The highest head diameter (38.28 cm) was obtained from RSK-3 at Libokemkem district whereas the lowest (15.5 cm) was obtained from Tesfa variety at Fogera district with the mean value of 25.33 cm [8].

Leaf length is influenced significantly by location at (P≤0.05). The maximum leaf length (24 cm) was recorded from Tesfa variety at Libokemkem district and the minimum value 16.03 cm was obtained from RSK-3 variety at Fogera location. Similarly, Lita (2022) in Philiphines studied on lettuce and the highest leaf length was 17.33 cm at the age of 30 days after transplanting. Bewuket and Shewaye (2020) at Gurage zone in Ethiopia found that leaf length was ranged from 11.06 to 23.12 cm. Leaf width also influenced significantly by variation of location and variety. In the same manner, the shortest leaf width (7.17 cm) was observed on the variety RSK-3 at Fogera and the maximum value of leaf width (17.40 cm) was recorded on Tesfa variety at Libokemkem site with the mean value of 11.4 cm. Similarly, Januka et al. (2021) in Nepal found that leaf length and leaf width had showed a highly significant difference between locations and variety with the value of leaf length ranged from 14-25 cm whereas leaf width ranged from13-20 cm. Bewuket and Shewaye (2020) obtained the maximum leaf width of 11.22 cm from the variety named “Great Lake” at Wulkite university research site in Southern part of Ethiopia [9].

Locations had showed a significant variation in the average number of leaves per plant. The average of number of leaves per plant in lettuce varies from 16.67 cm to 39.34 cm. The maximum value of leaves number per plant was recorded from Tesfa variety at Libokemkem whereas the lowest value was obtained from RSK-3 at Fogera (Table 2).

Table 2: Combined mean of growth, yield and yield related parameters of lettuce varieties from two tested locations (Fogera and Libokemikem) in 2020 rainy season.

The analysis of variance for yield and yield related traits in lettuce that tested at Libokemkem and Fogera districts revealed significant varietal difference for fresh leaves yield. The highest yield was recorded from Tesfa variety at both locations. The higher leaf yield of Tesfa (34.15 ton/ha) and RSK-3 (26.8 ton/ha) was obtained at Libokemekem than Fogera district (Tesfa (3.89 ton/ha) and RSK-3(3.67 ton/ha) [10]. Generally, all studied traits at Libokemkem district showed a higher value than at Fogera district. This indicates that swampy area similar to Fogera rice growers’ land couldn’t preferable for large scale production of lettuce in the main cropping season. According to variety selection, Tesfa variety is performed better from both Fogera and Libokemkem districts. Luchia et al.(2018) also studied on lettuce varieties in Southeastern part of Tigray and found that improved Tesfa lettuce variety had good acceptance by farmers with its quality, yield, late flowering or slow bolting and high market acceptability. Bewuket and Shewaye (2020) found lettuce yield of 9.45 ton/ha at Gurage zone in Ethiopia (Figure 1) [10,12].

Figure 1: Field performance of lettuce varieties at Libokemkem district.

Most yield and yield related traits of each variety showed a nonsignificant difference between the year 2020 and 2021 at Fogera. However, leaf length, leaf width, number of leaves per plant from tesfa variety showed a significant difference between the seasons. While, only head diameter and leaf length were showed a significant difference from RSK-3 lettuce variety (Table 3).

Table 3: Combined mean of growth, yield and yield related parameters of lettuce varieties from two tested rainy seasons of 2020 and 2021 at Fogera district.

Seeds of Tesfa and RSK-3 varieties were maintained and multiplied at Fogera National Rice Research and Training Center (FNRRTC) research station by isolation distance for end user farmers and researchers for promotion and future extra investigation works (Figure 2) [13,14].

Figure 2: Seed maintenance of lettuce varieties at Fogera National Rice Research and Training Center (FNRRTC) research field station.

Conclusion and Recommendations

Location had showed a highly significant difference for stand count, head diameter, leaf length, and number of leaves per plant and fresh vegetative yield of lettuce varieties. The highest value for leaf length (24 cm),leaf width (17.4 cm), number of leaves per plant (39.34) and fresh leaves yield (34.15 t/ha) was recorded from Tesfa variety at Libokemkem district. Whereas, the lowest value for leaf length(16.03 cm),leaf width (7.17 cm),number of leaves per plant (16.67) and fresh leaves yield (3.67 t/ha) was recorded from RSK-3 variety at Fogera. The highest yield was recorded from Tesfa variety at both locations. The study concludes that Tesfa lettuce variety performed better as this had showed large in head diameter, longer leaf length and width with more number of leaves per plant that subsequently provided highest fresh leaves yield of lettuce. Therefore, it could be concluded that Tesfa variety might be recommended for farmers and growers of lettuce in the study area.

Competing Interests

The authors declare that they have no competing interests.

Acknowledgements

Authors acknowledged Holeta Agricultural Research Center for providing seeds of lettuce varieties. The authors also obliged to acknowledge cool season vegetable program for providing budget to this research study. The authors extend their thanks to Fogera National Rice Research and Training Center horticulture team especially for Mr. Dessie Getahun for his guidance, advice and encouragement to organize and complete this research study and for Mr. Desalegn Sisay and Maru Adugna for their close follow-up of the research sites with subsequent data collection works.

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