Optimizing emmer wheat (Triticum dicoccum L.) yield: Strategies for lodging prevention with foliar application of plant growth regulators

Introduction

The emmer wheat (Triticum dicoccum L.) is reported to be grown on a very restricted scale in Gujarat, Maharashtra and Karnataka, where it is known under the names Popathiya, Samba and Khapli it means 'crusty' respectively. In general emmer wheat varieties are rich source of protein and complex carbohydrate (dietary fibre) as compared to bread wheat and it keeps one full for longer and hence helps in weight loss. It possesses excellent grain quality traits and is rich source of dietary fibres of more than 16 percent. It helps the digestion of carbohydrates, which slows down the release of glucose into the bloodstream maintaining a steady blood sugar level and makes it ideal for diabetic people. It contains good amount of proteins (11.8 to 15.3%), total carbohydrates (78.7 to 83.2%) and also this grain is rich in polyphenols which helps to prevent cancer, cardiovascular diseases and neurodegenerative diseases. The traditional products of emmer wheat varieties have better taste, texture and flavour (Singh, 2015) [10] . Globally, wheat is cultivated in an area of 222 Mha with a production of 779 Mt and having the productivity of 3510 kg/ha (Anon., 2022) [3] . In India, the estimated area 31.61 Mha with production of 109.52 Mt and productivity of 3464 kg/ha (Anon., 2021) [2] . Uttar Pradesh has the highest area (9.85 M ha) and production (35.50 Mt) followed by Madhya Pradesh (6.39 Mha, 17.62 Mt). Punjab has the highest average productivity of 4862 kg/ha followed by Haryana with 4836 kg/ha (Anon., 2021) [2] . Karnataka is unique in cultivation of three species, namely, bread, durum and dicoccum wheat. In Karnataka, the area under wheat is 1.67 lakh ha with annual production of 1.79 Mt and productivity of 1198 kg/ha. Dicoccum wheat lodging was notably pronounced, resulting in a substantial yield reduction of approximately 30-40%. This lodging phenomenon is prevalent, primarily attributed to the increased plant height in local varieties when compared to newer variants. The North-West winds, known as Paduvana gali, carry higher moisture content. Consequently, the panicles absorb this moisture, becoming weightier and compelling the plants to undergo lodging. Lodging is a complex issue influenced by factors like wind, rain, topography, soil type, previous crop management and disease. It often occurs due to conditions promoting excessive plant growth, leading to the vulnerability of wheat stems to lodging during later stages such as heading and grain filling, causing significant yield loss. Lodging hampers light absorption, intra-plant water availability and nutrient translocation, ultimately reducing yields. To address this, dicoccum is being experimented with, along with plant regulators like chlormequat chloride (CCC) and Ethephon. These regulators can modify stem stand, regulate plant growth and improve source-sink relationships, resulting in more grains per spike and increased grain yield. By preventing, delaying, or reducing lodging in cereals, the quantity and harvest ability of grains are enhanced, ensuring a favourable economic outcome. Consequently, an experiment was launched to assess the yield potential of both improved and local genotypes of emmer wheat through the application of plant growth regulators.

Materials and Methods

Description of field sites and experimental design: A field trial was conducted during Rabi season of 2020-21 and 2021-22 to study the "Optimizing emmer wheat yield: Strategies for lodging prevention with plant growth regulators". The Dharwad region experiences a weather characterized by hot and dry summer along with medium cold winters. The soil type of the experimental site was medium deep black soil with clay loam texture. It was low in available nitrogen (189.74 kg/ha), high in available phosphorous (36.24 kg/ha) and potassium (368.25 kg/ha). Additionally, the soil had a neutral pH of 7.51 and EC was 0.27 dS/m. The experiment was laid out in split plot design with three replications. The experiment consists of four genotypes (V1-MACS 2971; V2-DDK 1029; V3-HW-1098 and V4-Gokak local) in main plots and five treatments (G1-Control; G2-CCC @ 1000 ppm l -1 water; G3-CCC @ 1500 ppm l -1 water; G4-Ethephon @ 10 ppm l -1 water and G5-Ethephon @ 10 ppm l -1 water) in sub plots. The seed rate used for sowing is 150 kg ha -1 with a row spacing of 20 cm. The recommended doses of fertilizer (RDF) at 120: 60: 30 kg N: P2O5: K2O ha -1 were applied. Nitrogen was administered in two equal splits, initially at sowing as a basal application and then 30 days after sowing. The complete amount of phosphorus and potassium was applied as a basal dose during sowing, alongside half of the nitrogen. Emmer wheat was cultivated following a specified set of agricultural practices. Irrigation was managed based on the crop's water requirements using the check basin method. The crop was sown on November 14 th and harvested on March 15 th in both years.

Estimating emmer wheat yield: The wheat crop underwent manual harvesting, leaving two border rows unharvested in both horizontal and longitudinal directions, with a 0.5 m gap in the longitudinal direction. Subsequently, the harvested wheat grain was gathered and subjected to oven-drying at 65-70 °C for 48 hours. The weight of the dried grain was then measured to calculate the economic yield. Harvesting was conducted from the net plot and the yield was quantified in quintals per hectare.

Lodging score

To score lodging the percent area of plant that lodged was estimated and the angle of stem lodging was estimated.

Statistical analysis

The investigation involved the meticulous compilation and analysis of recorded data, employing statistical techniques such as analysis of variance (ANOVA) for split plot design. Fisher's ANOVA method, as elucidated by Gomez and Gomez (1984) [5] , was adopted for this purpose. Standard error of mean and coefficient of variability were computed for each set of observations pertaining to various characteristics. The mean values for the main plot, sub-plot and interaction effects were subjected to separate analysis through Duncan's Multiple Range Test (DMRT) using corresponding error mean sum of squares and degrees of freedom values, facilitated by the OP-STAT program.

Results and Discussion

The performance of different emmer wheat genotypes in terms of growth, yield and yield attributes was assessed In this investigation, differences in plant height, lodging score and 1000-grain weight among various genotypes were not statistically significant. However, the Gokak local genotype (V4) exhibited numerically higher values: 79.94 cm in plant height, 2.44% in lodging score and 44.18 g in 1000-grain weight, surpassing other genotypes (Table 1 &2). These variations are likely attributed to the unique genetic characteristics of specific genotypes, aligning with the findings of Sujatha et al., (2018) [13] . The results showed a significant increase in the number of effective tillers per square meter for all genotypes, except the Gokak local genotype. Particularly, the MACS 2971 genotype (V1) exhibited the highest count of effective tillers at 349.71 m -2 , outperforming other genotypes (Table 2). These differences can be attributed to the unique genetic traits of individual genotypes, aligning with similar findings reported by Rajala and Peltonen, 2021 [9] . In the present investigation the results indicated that, among the different genotypes there is no significant difference was recorded in grain, straw and biological yields except gokak local genotype. Where, as numerically higher grain (40.45 q/ha), straw (66.75 q/ha) and biological yields (105.95 q/ha) was recorded in HW 1098 genotype (V3) as compared to other genotypes (Table 3 &4). These might be due to higher yield attributing character of particular genotype. Similar type of results was also obtained by Guled (1993) [6] . The findings indicate that, with the exception of the Gokak local genotype, all emmer wheat genotypes exhibited significantly higher gross returns, net returns and benefit-cost ratios. Notably, HW 1098 (V3) displayed superior performance, registering elevated gross returns (₹. 1,48,924 ha -1 ), net returns (₹. 1,13,061 ha -1 ) and a benefit-cost ratio of 4.16 compared to other genotypes. This outcome is likely linked to the higher grain yield and straw yield recorded in HW 1098, (Table 4). Importantly, similar results were corroborated by Sujatha et al., (2018) [13] .

Effect of foliar application of plant growth regulators on growth and yield parameters of emmer wheat

The foliar application of ethephon @ 30 ppm per liter of water after 30 to 35 DAS (G5) recorded significantly lower plant height (67.96 cm), lodging score (0.93%), higher number of effective tillers (361.17 m -2 ), thousand grain weight (44.19 g), grain yield (42.70 q/ha), straw Mean followed by the same letter(s) did not differ significantly by DMRT (p= 0.05) yield (70.45 q/ha), biological yield (112.81 q/ha), gross returns (₹. 1,57,182 ha -1 ), net returns (₹. 1,22,188 ha -1 ) and benefit cost ratio (4.49) and it was on par with (G3) foliar application of CCC (2-chloroethyl trimethyl ammonium chloride) at the rate of 1500 ppm per liter of water after 30 to 35 DAS. However, significantly higher plant height (83.13 cm), lodging score (4.06%), lower number of effective tillers (301.75 m -2 ), thousand grain weight (41.98 g), grain yield (33.11 q/ha), straw yield (54.64 q/ha), biological yield (87.11 q/ha), gross returns (₹. 1.21,909 ha -1 ), net returns (₹. 88,374 ha -1 ) and benefit cost ratio (3.64) was recorded (G1) in control as 1, 2, 3 & 4). Ethephon (2 chloro ethyl phosphonic acid) and CCC (chlormequat chloride) were reported to be useful in reducing the plant height (Ali, 1993) [1] . Ethephon led to decrease in the length of peducle, middle internode and to some extent. Basal internodes (Knapp et al., 1987) [7] . Ethephon application was found to increase lignin content and decrease cellulose content in lower and middle internodes. It decreased ADF (Acid detergent fibre) and prevented lodging in the basal internodes and increased potassium content of second internode (Tripathi et al., 2003) [12] . The present investigation included identification of appropriate growth regulator with effective dosage in reducing the lodging and also to find out a variety which responds favourably in improving its growth and yield to plant growth. These might be a result of reduces the lodging of emmer wheat plant by foliar application of ethephon through decrease in the length of peducle, middle internode and to some extent basal internodes (Knapp et al., 1987) [7] , simultaneously increased tiller numbers m -2 , stem wall thickness for the 1 st , 2 nd and 3 rd internodes (Tripathi et al., 2003) [12] .

Interaction effect of different genotypes and foliar application of plant growth regulators on growth and yield parameters of emmer wheat

The genotypes of HW 1098, MACS 2971 and DDK 1029 with foliar application of ethephon @ 30 ppm per liter of water after 30 to 35 DAS (V3G5, V1G5 and V2G5) recorded significantly lower plant height (62.35, 66.00 and 69.35 cm, respectively) and lodging score (1.00, 0.73 and 0.83%, respectively) and it was on par with V1G3, V2G3, V3G3 and V4G3, respectively (Table 1). Nevertheless, a notable increase in plant height and lodging score was observed in all genotypes without foliar application of plant growth regulators. This phenomenon may be attributed to the combined positive impact of specific genotypes and the absence of plant growth regulators. These outcomes align with the observations made by Knapp et al. (1987) [7] . The genotype of DDK 1029 with foliar application of ethephon @ 30 ppm per liter of water after 30 to 35 DAS (V2G5) recorded significantly higher number of effective tillers (391.83 m -2 ) followed by V1G3, V1G4, V2G3, V2G5, V3G3 and V3G5. However, significantly lower number of effective tillers was recorded in (V4G1 and V4G2) without foliar application of plant growth regulators and foliar application of CCC @ 1000 ppm per liter of water with gokak local genotype (279.84 and 285.00 m -2 , respectively) (Table 2). These could be linked to a consequence of combined positive influence of respective genotypes and plant growth regulators. Similar results were shown (Sujatha et al., 2018) [13] . The genotypes of MACS 2971, DDK 1029 and HW 1098 with foliar application of ethephon @ 30 ppm per liter of water and CCC @ 1500 ppm per liter of water after 30 to 35 DAS recorded significantly higher grain yield (V1G3-44.00 q/ha, V1G5-44.24 q/ha, V2G5-43.03 q/ha, V3G3-43.83 q/ha and V3G5-44.34 q/ha), straw yield (V1G3-72.61 q/ha, V1G5-72.99 q/ha, V2G5-71.00 q/ha, V3G3-72.32 q/ha and V3G5-73.16 q/ha) and biological yield (V1G3-117.72 q/ha, V1G5-117.73 q/ha, V2G5-114.49 q/ha, V3G3-114.40 q/ha and V3G5-116.28 q/ha) as compared to without foliar application of plant growth regulators in gokak local genotype (V4G1) (Table 3 &4). These effects are likely the result of the combined positive influence of both specific genotypes and application of plant growth regulators on the growth and yield parameters of emmer wheat. These findings are consistent with the results reported. The genotypes of MACS 2971, DDK 1029 and HW 1098 with foliar application of ethephon @ 30 ppm per liter of water and CCC @ 1500 ppm per liter of water after 30 to 35 DAS recorded significantly higher gross returns V1G3 (₹. 1,62,001 ha -1 ), V1G5 (₹. 1,62,851 ha -1 ), V3G3 (₹. 1,61,359 ha -1 ) and V3G5 (₹. 1,63,238 ha -1 ) and it was on par with V2G5 (₹. 1,58,415 ha -1 ). However, significantly lower gross returns were recorded in (V4G1) without foliar application of plant growth regulators in gokak local genotype (₹. 1,12,953 ha -1 ) (Table 4). These could be caused by higher grain and straw yields was recorded in respective treatments. This is in accordance with the findings of (Sujatha et al., 2018) [13] . The foliar application of ethephon @ 30 ppm per liter of water with genotype of HW 1098 (V3G5) recorded significantly higher net returns (₹. 1,28,353 ha -1 ) and it was on par with V1G5 (₹. 1,27,530 ha -1 ) and V2G5 (₹. 1,23,530 ha -1 ). Where, as significantly lower net returns were recorded in V4G1 without foliar application of plant growth regulators in gokak local genotype (₹. 79,418 ha -1 ) (Table 4). These may be attributed to higher grain and straw yields was recorded in respective treatments. This is in accordance with the findings of (Sujatha et al., 2018) [13] .

The foliar application of plant growth regulators and various genotypes significantly influences benefit-cost ratio of emmer wheat. The genotypes of MACS 2971 and HW 1098 with foliar application of ethephon @ 30 ppm per liter of water after 30 to 35 DAS (V1G5 and V3G5) recorded significantly higher benefit cost ratio (4.61 and 4.68, respectively) and it was on par with V2G5 (4.54). However, significantly lower benefit cost ratio was recorded in (V4G2) gokak local genotype with foliar application of CCC @ 1000 ppm per liter of water after 30 to 35 DAS (3.21) (Table 4). These could result from higher grain and straw yields was recorded in respective treatments. This is in accordance with the findings of (Sujatha et al., 2018) [13] .

Conclusion

In summary, the utilization of the plant growth regulator ethephon at 30 ppm resulted in a reduction in growth parameters such as plant height and lodging score across all genotypes. Simultaneously, it positively influenced grain yield, yield attributes and economic factors in all the genotypes.

References

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