Evaluation of irrigated rice ( Oryza sativa L.) varieties under irrigation condition at Dasenech Distinct, South Omo Zone

Rice crop is essential in a country. Still, the production and productivity are low due to uncovering a suitable area for rice production and the shortage of improved and unedited well-adapted variety. To solve this problem, the study was conducted in Dasenech district during (2020/21 and 2021/22) cropping seasons to select well-adapted varieties. The study contains 6 varieties (Gode, Shebele, Chewaqa, Kallafo, Nerica-15, and Pawe-2). For this study used a randomized complete block design with three replications. Yield and other trait data were collected and subjected to analysis of variance. The result of the analysis of variance showed that all parameters were significantly affected among tested rice varieties. The Pawe-2 variety gave the highest grain production (6284.7 kg ha -1 ) among the tested varieties. Based on the study result, it can be suggested that variety Pawe-2 perform well and is suitable for agro-pastoral in the Dasenech area under irrigation condition and its similar agro-ecology.


Introduction
Rice production in a country is recent when related to other cereal crops. In the Fogera and Gambela regions, it was first introduced in the 1960s (Gebey et al., 2012). In a rice grain, there are 75-80% starches, 12% liquids, and 7% proteins (Hossain et al., 2015). Moreover, it is an essential source of minerals (magnesium, phosphorus, and calcium) (Oko et al., 2012). It is also a gluten-free food, and rice benefits from the growing popularity of gluten-free diets (Topper, 2014). Not only is rice used as food, but it also has byproducts (straws and husks) that can be utilized as a source of fertilizer and substitutes. According to a study by Halos-Kim (2015), "Ethiopian rice cultivation has a big potential for guaranteeing food security and reducing imported rice. Rice is one of the most significant food crops in Ethiopia. Rice in the country was cultivated on around 57,575.72 ha of land covered, and 170,630.1 tons were produced with an average productively of 2.96 tons ha -1 in 2019/20 cropping season (CSA, 2019/20). Unfortunately, this yield is huge between the yield potential of rice (4.0 to 5.8 tons ha -1 ) (MOANR, 2021). There are different factors for rice production. Among them, shortage of improved rice variety, inappropriate agronomic management, and unidentified soil fertility for rice) for a specific location are the main issues limiting rice production (Abebaw, 2018). One of the biggest challenges in rice-growing countries is the lack of adaptable and high-yielding improved rice varieties. This study was conducted to select well-performed irrigated rice variety/ies under irrigation conditions at Dasenech distinct.

The study site
The study was conducted at Dasenech distinct (Omorate) for two years of cropping season from 2020/21 and 2021/22. It is located at an altitude of 365 above meter see level and is situated b/n 54°37′

Treatments and experimental setup
Six rice varieties Gode, Shebele, Chewaqa, Kallafo, Nerica-15, and Pawe-2 were used for this investigation. For this study used a randomized complete block design (RCBD) with 3 replications.

Experimental management and procedure
The land was ploughed, disked and harrowed. The well-prepared land was ridged by a tractor at a ridge of 0.6 meters; it was manually corrected. Pots and replications were two meters apart. Seven rows could fit on the plot, 16.8 m 2 (4.2 x 4.0) meters, at 0.3-meter intervals, on ridges with two rows. Sixty (60) kg ha -1 seed rate were manually drilled into rows. At a rate of one hundred (100) kg ha -1 of NPSB were applied at planting, and one hundred fifty (150) kg ha -1 of urea was applied twice, once at the tillering and once during the heading stage.
From planting through heading, the furrow method was used to furrow irrigation water at 5-7 day intervals. From flowering to physiological maturity, the furrow method was used each 8-10 days, based on the weather. 20 days, 40 days, and 60 days following emergence, the 1 st , 2 nd and 3 rd weddings were carried out.

Collected data
Phenology, growth, yield and yield components parameters were collected. Under phenology and growth parameter, Days to 85% maturity and Plant height (cm) were recorded. Under yield and yield components parameter, Panicle length (cm), Number of productive tillers per plant, Number of filled grains per panicle, Total above-ground dry biomass yield (kg), Hundred seed weight (g) and Grain yield were recoded.

Data analysis
All collected data were analyzed using SAS software version 9.3 (SAS, 2009). This means separation was carried out by using LSD at 5%.

Analysis of variance
Before the combined analysis of variance, the homogeneity of error variances was tested, and all of the traits showed homogeneous error variances. Having this confirmation, the data were pooled across years and a combined analysis of variance over two years average was performed.

Phenology and growth parameters
The pooled analysis of variance showed that days to physiological maturity, lodging incidence and productive tiller were influenced by rice varieties.
Combined mean values, the highest days (140.7) and (139.1) of maturity were recorded from Gode and Shebele varieties, while the lowest days (111.8) of maturity were recorded from Pawe-2 variety (Table 1). This result agreed with the report of (Zelalem et al., 2019), who reported that days to maturity were significantly affected by rice varieties. Effects of pooled analysis for lodging incidence ranged from 35.8% -5.0% for Chewaqa and Pawe-2, respectively. This might have occurred due to genetic variation in the rice varieties. Combined analysis results for productive tillers ranged from 16.5 for Nerica-15 variety to 21.9 for Pawe-1 variety ( Table 1). The results conform to Alemu and Assefa (2016).

Plant height and panicle length
The study revealed significant variances among rice varieties in plant height and panicle length (

Yield and yield components
The pooled analysis of variance showed a significant difference in number of filled grains per panicle and above-ground dry biomass (Table  3). Variety Pawe-2 (236.2), followed by Chewaqa (158.9) was the highest variety for the number of filled grains per panicle, while Nerica-4 (151.6) was the lowest number of filled grains per panicle variety. This result was in line with the finding of Almu and Assefa (2016), who found that the number of filled grains per panicle was significantly affected by rice varieties. The highest above-ground dry biomass (20197 kg ha -1 for Gode variety, 19563 kg ha -1 for Shebele variety and 18710.5 kg ha -1 for Pawe-2 variety, while the lowest above-ground dry biomass (13375 kg ha -1 ) was recorded form Chewaqa variety (Table 3). This result was in agreement reported by aligns Altaye (2019).

Grain yield, thousand seed weight and harvest index
The combined analysis of variance showed significant differences in grain yield, thousand seed weight, and harvest index among tested varieties (Table 4). The highest grain yield (6284.7 kg ha -1 ) was recorded from variety Pawe-2, and the lowest grain yield (3928.0 kg ha -1 ) was recorded from Chewaqa. This result agreed with Ullah et al. (2016), who observed variable grain yield among the rice varieties. Similarly, significant variations in grain yield were reported by Mulugeta et al. (2012), who tested rice under rain-fed conditions. The highest thousand seed weight (34.6 g) was recorded for variety Pawe-2, and the lowest thousand seed weight (25.1 g) was recorded for variety Shebele (Table 4). The variation in thousand seed weight might be due to the differences in length and breadth of the seeds that were partly controlled by the genetic makeup of the genotypes (Rahman et al., 2018). This result is in line with Wubale et al. (2015), who obtained minimum and maximum values for 1000 seed weights 26.15 and 35.41 g, respectively.
The highest harvest index (0.39) was recorded from variety Pawe-2-1 and followed (0.21) by variety Shebele while the lowest harvest index (0.26) was recorded from variety Selam (Table  4). Conclusion A significant cereal crop in Ethiopia is rice. However, the production and productivity are low due to uncovering suitable areas for rice production and the shortage of improved and unedited, well-adapted varieties. To solve this problem, the study was conducted in the Dasenech district during (2020/21 and 2021/22) cropping seasons with the objective of selecting well-adapted varieties/ies. Of the investigated treatments, the Pawe-2 variety's grain production (6284.7 kg ha -1 ) was the greatest. We saw field visits for this variety, which indicates that agropastoralists are interested in it as well. Since grain and animal feed is made from its stalk and leaves. As a result, Pawe-2 variety can be advised to prompt in the study area.