Response of Forage Yield and Quality of Oats (Avena sativa L.) to Planting Distances and Mowing Dates

A field experiment was carried out during the winter season of 2020-2021 in the Habbaniyah district, west of Baghdad, to study the response of forage yield and quality of oats Avena sativa L. var. Shifaa to planting distances and mowing dates. A split plots arrangement according to the RCBD at three replications was used. The main plots included planting distances, while the subplots included the mowing dates. The study’s results indicated that the planting distance of 25 cm between lines was significantly superior in the green forage yield and fiber percentage 12.00 ton ha-1 and 37.61%, respectively. In comparison, the planting distance of 20 cm between lines was significantly superior in the protein percentage 12.34%. As for the mowing dates, the mowing after 70 days was selected substantially in the forage yield and fiber percentage. The mowing after 50 days was significantly superior in protein percentage 12.28%. The interaction between studied factors significantly affected the most studied traits.


Introduction
The livestock sector in Iraq constitutes an essential part of the agricultural sector, as it is no less important than the vegetable sector.Despite the importance of the livestock sector, it suffers from the problem of deterioration of production and its quality, as well as a lack of forage, especially in the winter season, as a result of the slow growth of alfalfa and clover due to low temperatures, which means a significant shortage of animal protein.Therefore, it is necessary to search for crops with high productivity and tolerant a low temperatures such as oats.Despite the success of oat cultivation in Iraq, it is still cultivated on a small scale to obtain green forage and grains, although it contains a good percentage of protein (9-12%) of dry matter [1].Oats (Avena sativa L.) is one of the winter cereal crops, which is characterized by the intensity of its vegetative growth and large number of its leaves, which gives it a high fodder nutritional value, in addition to the length of its growing season and giving it several mowing during the season as well as it tolerates low temperatures in the autumn season.So, it is considered more suitable for cultivation than many forage crops [2].Oats are widely used in the world as livestock feed due to its good forage quality as well as high yield [3].However, oats in Iraq is a secondary crop, as it is grown either alone or mixed with forage crops such as alfalfa and clover, despite some cultivars proved successful in terms of green forage yield such as Oats-11 and Shifaa.The productivity of any crop is a reflection of the genotype x environment (G × E) 1259 (2023) 012094 IOP Publishing doi:10.1088/1755-1315/1259/1/012094 2 interaction and field operations, and the understanding these aspects will help specialists to choose the appropriate time for plant mowing, which comes at the forefront of the processes that lead to increased forage production and improvement of its quality.Also, to introduce or devise any variety, it is necessary to determine its planting density to know its environmental requirements in order to obtain a high yield and good quality.Therefore, this research was carried out to determine the best planting distance and mowing date of this crop to obtain the highest yield and beat quality.

Materials and Methods
A field experiment was carried out during the winter season of 2020-2021 in the Habbaniyah district, west of Baghdad, to study the response of forage yield and quality of oats (Avena sativa L. var.Shifaa) to planting distances and mowing dates.A split plots arrangement according to the RCBD at three replications was used.The main plots included four planting distances of 10, 15, 20 and 25 cm between lines, while the sub plots included three mowing dates of 50, 60 and 70 days after planting.The required soil service operations were carried out.Then the experimental land was divided into 36 experimental units.The area of each experimental unit was 6 m 2 (3×2 m).The seeds were sown on 15 October 2020 at a seeding rate of 140 Kg ha -1 .Phosphate fertilizer was added as triple superphosphate (45% P 2 O 5 ) at 100 Kg P ha -1 at one dose before planting [4].In contrast, the nitrogen fertilizer was added at a level of 200 Kg N ha -1 as urea (46% N) at three doses, the first at the planting, while the second and third were added after each mowing for all experimental units to ensure the restoration of growth after mowing [5].Crop service operations were conducted as needed.

Studied Traits
 Green forage yield (ton ha -1 ): The plants of the two middle lines were mowed from each experimental unit at the height of 5-7 cm from the soil surface, and then the green forage yield was immediately weighed after mowing using an electronic [1]. Dry matter yield (ton ha -1 ): It was calculated according to the method used by [6]. Total ash Percentage (%): It was estimated using the Muffle Furnace device according to the method followed in A.O.A.C [7]. Fibers percentage (%): It was estimated using the Tecator Fibertic System according to the method used in A.O.A.C. [7]. Protein percentage (%): The nitrogen percentage was estimated using the Micro Kjeldahl device, and then the protein percentage was calculated from the following equation [7]: Protein percentage (%) = Nitrogen percentage (%) × 6.25  Oil percentage (%): It was estimated according to the method used in [7].The data were statistically analyzed using the Genstat program, and the least significant difference Lsd test at 0.05 probability level was used to compare between averages.

Green Forage Yield (ton ha -1 )
Table (1) results indicate a significant effect of planting distances between lines on the green forage yield.The distance of 25 cm between lines achieved the highest average of this trait (12.00 ton ha -1 ) with a non-significant difference with the distance of 10 cm between lines (11.96 ton ha -1 ) compared with the distance of 15 cm between lines which achieved the lowest average (10.25 ton ha -1 ) with a non-significant difference with the distance of 20 cm between lines (10.33 ton ha -1 ).The reason for the superiority of the high distance (25 cm between lines) may be attributed to an increase in the allocated area for plants, the lack of shading, the increase of interception of the most significant amount of incident solar radiation and the increase the photosynthesis process, which lead to an increase the accumulation of dry matter and provide optimal growth for the plant.The mowing dates also significantly affected the green forage yield (Table 1).The mowing after 70 days of planting gave the highest average of this trait (12.94 ton ha -1 ) compared with the mowing after 50 days of planting which showed the lowest average (10.40 ton ha -1 ) with a non-significant difference with the mowing after 60 days of planting (10.60 ton ha -1 ).The increase of green forage yield when mowing was delayed could be attributed to the more extended vegetative growth period, which led to an increase in plant growth and accumulation of more photosynthetic components and then increased the green forage yield compared with early mowing.This result aligns with [8].The interaction between planting distances and mowing dates didn't significantly affect this trait (Table 1).Table 1.Effect of planting distances, mowing dates and interaction between them on the green forage yield (ton ha -1 ).

Dry Matter Yield (ton ha -1 )
Table (2) results reveal a significant effect of planting distances between lines on the dry forage yield.
The distance of 10 cm between lines gave the highest average of this trait (5.70 ton ha -1 ) compared with the distance of 25 cm between lines which showed the lowest average (3.37 ton ha -1 ) with a nonsignificant difference with the distance of 15 cm between lines (3.72 ton ha -1 ).The superiority of the low distance (10 cm between lines) may be due to increased plants per unit area.These results agree with [9,10].According to the research data, the mowing dates significantly affect the dry forage yield (Table 2).The mowing after 70 days of planting achieved the highest average of this trait (5.54 ton ha -

1
) compared with the mowing after 50 days of planting, which reached the lowest average (3.28 ton ha -

1
).The increase in dry forage yield when mowing was delayed could be attributed to the superiority of the same mowing date in the green forage yield (Table 1).This result agrees with [11].The above results show that yield increased when the mowing date was delayed, and the planting distance between lines was reduced.The interaction between planting distances and mowing dates didn't significantly affect this trait (Table 2).Table 2. Effect of planting distances, mowing dates and interaction between them on the dry forage yield (ton ha -1 ).

Total Ash Percentage (%)
Table (3) shows a significant effect of planting distances between lines on the total ash percentage.The distance of 25 cm between lines achieved the highest rate of total ash (13.23%) with a nonsignificant difference with the distance of 15 cm between lines (12.52%) compared with the distance of 10 cm between lines which achieved the lowest percentage (10.52%).The reason for the superiority of the high distance (25 cm between lines) in this trait may be attributed to an increase in the representation of nutrients within the plant tissues.This result is in line with the results of [9].
Regarding mowing dates, the results in Table (3) indicate that mowing after 50 days of planting was significantly superior and gave the highest percentage of total ash (13.40%) compared with mowing after 70 days of planting, which provided the lowest rate (10.77%).The increase could be attributed to the vitality and activity of plants in their early stages of growth, which enhances the absorption of nutrients, vitamins and minerals that lead to new plant tissues ( [9].The interaction between the two studied factors had significant effect on this trait (Table 3), the 25 cm between lines × mowing date after 50 days of planting combination recorded a highest value (15.07%), while the 10 cm between lines × mowing date after 70 days of planting combination recorded a lowest value (8.67%).Table 3.Effect of planting distances, mowing dates and interaction between them on the total ash percentage (%).

Fibers Percentage (%)
The results in Table (4) indicate that the distance of 25 cm between lines was significantly superior and recorded the highest percentage of fiber (37.23%) with a non-significant difference with the distance of 20 cm between lines (37.06%) compared with the distance of 10 cm between lines which recorded the lowest percentage (34.11%).The reason for the superiority of the high distance (25 cm between lines) in this trait may be attributed to an increase in the stem diameter, which leads to an increase in the percentages of cellulose, hemicellulose and lignin, which are the main components of the fibers.These results are similar to the results [6].The results in Table (4) indicate that mowing after 70 days of planting was significantly superior and achieved the highest percentage of fiber (39.29%)compared with mowing after 50 days of planting, which reached the lowest rate (33.63%).
The increase in fiber percentage when mowing was delayed may be due to an increase in cellulose, hemicellulose and lignin, which are the main components of fiber.These results are consistent with the results of [12].The interaction between planting distances and mowing dates didn't significantly affect this trait (Table 4).Table 4. Effect of planting distances, mowing dates and interaction between them on the fiber percentage (%).

Protein Percentage (%)
The results in Table (5) reveal that the distance of 20 cm between lines was significantly superior and gave the highest percentage of protein (12.34%) with a non-significant difference with the distance of 25 cm between lines (11.16%) compared with the distance of 10 cm between lines which gave the lowest percentage (8.54%)with a non-significant difference with the distance of 15 cm between lines (9.16%).The reason for superiority may be attributed to the role of wide distances in reducing competition between plants on the growth factors, which led to an increase in the photosynthesis process and then an increase in the supply of NADH and NADPH compounds that donate the necessary electrons for reduction of nitrates to ammonia [13].Regarding mowing dates, the results in Table (5) show that mowing after 50 days of planting was significantly superior and achieved the highest percentage of protein (12.28%) compared with mowing after 70 days of planting, which reached the lowest rate (8.40%).It appears from the above results that the percentage of protein increased at early mowing.This may be attributed to increased nitrogen content in the forage, which is a significant component in protein synthesis.This result is consistent with [14].The interaction between the two studied factors substantially affected this trait (Table 5).The 20 cm between lines × mowing date after 50 days of planting combination had the highest value (15.88%).At the same time, the 10 cm between lines × mowing date after 70 days of planting combination had the lowest value (7.84%) with a non-significant difference with 25, 20 and 15 cm between lines × mowing date after 70 days of planting, 15 and 10 cm between lines × mowing date after 60 days of planting and 10 cm between lines × mowing date after 50 days of planting combinations (8.76, 8.90, 8.13, 9.12, 8.24 and 9.56%) respectively.6) shows a significant effect of planting distances between lines on the oil percentage.The distance of 20 cm between lines recorded the highest rate of oil (2.87%) with a non-significant difference with the distance of 25 cm between lines (2.54%) compared with the distance of 10 cm between lines which recorded the lowest percentage (1.98%) with a non-significant difference with the distance of 15 cm between lines (2.11%).The superiority may be attributed to the fact that the wide distances represented the best nutrients compared with narrow distances.As for mowing dates, the results in Table (6) reveal that mowing after 50 days of planting was significantly superior and gave the highest percentage of oil (2.84%) compared with mowing after 70 days of planting which showed the lowest rate (1.91%).The decrease when mowing is delayed could be due to the reduction of crude fat due to the length of the vegetative growth stage [8].The interaction between the two studied factors significantly affected this trait (Table 6).The 20 cm between lines × mowing date after 50 days of planting combination recorded the highest value (3.40%) with a non-significant difference with 25 and 15 cm between lines × mowing date after 50 days of planting and 25 and 20 cm between lines × mowing date after 60 days of planting combinations (2.87, 2.80, 2.77 and 2.87%) respectively.In contrast, the 15 cm between lines × mowing date after 70 days of planting combination recorded the lowest value (1.56%) with a non-significant difference with 25, 20 and 10 cm between lines × mowing date after 70 days of planting, 15 and 10 cm between lines × mowing date after 60 days of planting and 10 cm between lines × mowing date after 50 days of planting combinations (1.98, 2.34, 1.76, 1.98, 1.89 and 2.30%) respectively.

Conclusion
We conclude from the study that there is a significant effect of the study factors and their interaction on the yield of green and dry forage, as well as their effect on improving the quality traits of the forage, and this in turn can produce highly palatable fodder for animals.

Table 5 .
Effect of planting distances, mowing dates and interaction between them on the protein percentage (%).

Table 6 .
Effect of planting distances, mowing dates and interaction between them on the oil percentage (%).