INFLUENCE OF ARBUSCULAR MYCORRHIZAL SPECIES (AM) ON DROUGHT TOLERANCE, NUTRIENT UPTAKE AND YIELD OF GROUNDNUT (Arachis hypogaea L.) UNDER WATER STRESS
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Date
2023-11-29
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Acharya N G Ranga Agricultural University
Abstract
The present investigation entitled “Influence of arbuscular mycorrhizal species (AM) on drought tolerance, nutrient uptake and yield of groundnut (Arachis hypogaea L.) under water stress” was undertaken at Agricultural College Farm, Bapatla during two consecutive years of rabi 2019-20 and 2020-21. The experiment was laid out in split plot design replicated thrice. There are two main treatments i.e., no stress (M0- irrigation is given as per irrigation schedule), and moisture stress at pegging and pod formation stages i.e., 40-60 DAS (M1) and seven sub treatments viz., no application of mycorrhiza (S0), soil application of Glomus fasciculatum (S1), Glomus aggergatum (S2), Glomus mosseae (S3), Glomus intraradices (S4), Gigaspora sps. (S5) and Acaulospora sps. (S6) each @12.5 kg ha-1
The results of the study revealed that significant differences were observed between main plot, sub plot treatments and their interactions. Soil moisture content of the plots subjected to drought stress was depleted from 15.65 to 7.41 per cent during 2019-20 and 14.12 to 6.83 per cent during 2020-21 upon imposition of water stress from 40 to 60 DAS. Lower soil moisture content was observed in the treatments that received the soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 which was 20.0 and 19.4 per cent lower, during 2019-20, and 19.5 and 19.2 per cent lower, respectively, during 2020-21, compared to control which indicates the enhanced the water uptake of plants by the extensive hyphal network of these mycorrhiza, whereas higher soil water content was recorded in plots without mycorrhizal application, Acaulospora sps. and Glomus aggregatum.
In the present study, water stress reduced the leaf area by 15.3 and 17.0 per cent, relative water content (RWC) by 21.1 and 19.0 per cent, leaf water potential (LWP) by 54.6 and 92.5 per cent and, total dry matter accumulation by 32.8 and 32.6 per cent, and increased the cellular leakage of solutes (MII) by 61.1 and 50.3 per cent and specific leaf weight (SLW) by 13.3 and 21.2 per cent compared to the irrigated groundnut plants during 2019-20 and 2020-21, respectively.
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Groundnut plants inoculated with Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 exhibited superior performance by improving physiological parameters viz., leaf area by 25.5 and 19.4 per cent, relative water content by 12.7 and 12.2 per cent, leaf water potential by 26.1 and 25.6 per cent, specific leaf weight by 16.8 and 13.8 per cent and total dry matter accumulation by 56.0 and 53.4 per cent, and reduced the cellular leakage of solutes by 14.3 and 13.7 per cent respectively during 2019-20 and during 2020-21, leaf area (17.4 and 18.4 %), relative water content (15.0 and 13.8 %), leaf water potential (27.7 and 27.1 %), specific leaf weight (12.2 and 11.8 %) and total dry matter accumulation (39.5 and 38.4 %) were increased and MII (13.6 and 11.8 %) was reduced in the present study.
Under water stress conditions, soil application of Glomus mosseae @ 12.5 kg ha-1 enhanced the leaf area (21.3 and 17.9 %), relative water content (12.1 and 19.8 %), leaf water potential (29.1 and 24.8 %) and total dry matter accumulation (96.2 and 68.7 %) compared to non-mycorrhizal plants under water stress conditions during 2019-20 and 2020-21, respectively and the soil application of Gigaspora sps. @ 12.5 kg ha-1 increased the leaf area by 14.2 and 12.6 per cent, relative water content by 8.1 and 16.9 per cent, leaf water potential by 25.6 and 22.7 per cent and total dry matter accumulation by 75.7 and 57.6 per cent in both the years, respectively. While, Acaulospora sps. @ 12.5 kg ha-1 recorded poor performance in improving the physiological parameters (leaf area, SLW, RWC, LWP, total dry matter accumulation and partitioning) of the plants both under irrigated and water stress conditions.
Groundnut plants subjected to water stress recorded 43.3, 28.5 and 40.4 per cent reduction in net photosynthetic rate, stomatal conductance and transpiration rate of groundnut during 2019-20 and 40.7, 29.7 and 46.2 per cent reduction during 2020-21, respectively, compared to the irrigation treatment. Soil application of Glomus mosseae @ 12.5 kg ha-1 recorded 51.9 and 46.2 per cent higher net photosynthetic rate followed by Gigaspora sps. @ 12.5 kg ha-1 which recorded 50.5 and 45.0 per cent higher net photosynthetic rate during 2019-20 and 2020-21, respectively, over control. While, higher stomatal conductance was recorded with Gigaspora sps. @ 12.5 kg ha-1 (45.6 and 37.4 per cent higher) followed by Glomus mosseae @ 12.5 kg ha-1 (41.8 and 32.3 per cent) in both the years, respectively. Under water stress, net photosynthetic rate and stomatal conductance of the treatment that received the soil application of Glomus mosseae was 66.9 and 53.1 per cent higher during 2019-20 and 46.2 and 69.1 per cent higher during 2020-21, respectively, and the soil application of Gigaspora sps. @ 12.5 kg ha-1 recorded 58.5 and 52.0 per cent and 45.0 and 67.6 per cent increase in net photosynthetic rate and stomatal conductance, respectively, in both the years.
The total leaf chlorophyll and carotenoid contents of water stressed groundnut plants were declined by 20.4 and 18.5 per cent, respectively, during 2019-20 and 17.8 and 20.7 per cent, respectively, during 2020-21. Soil application of Glomus mosseae enhanced the total chlorophyll and carotenoid contents in leaves by 42.9 and 65.9 per cent, respectively during 2019-20 and 27.1 and 41.9 per cent, respectively during 2020-21. Whereas, Gigaspora sps. @ 12.5 kg ha-1 increased the total chlorophyll and carotenoid contents in leaves by 38.6 and 61.4 per cent, respectively, during 2019-20 and by 26.4 and 39.5 per cent, respectively during 2020-21. Under drought stress, the leaf chlorophyll content of the treatment that received the soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 was 73.0 and 46.8 per cent higher, during 2019-20 and 32.5 and 23.8 per cent higher, respectively, during 2020-21 than the control plants under drought stress. The
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increase in leaf carotenoid content of the treatment that received the soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 was 91.9 and 37.6 per cent, during 2019-20 and 52.6 and 34.2 per cent, respectively, during 2020-21, over non-AM plants under drought stress.
A significant increase in antioxidant metabolites such as ascorbate (80.2 and 79.0 per cent) and proline contents (74.0 and 118.0 per cent) were noticed in the groundnut plants subjected to water stress over irrigated plants. Enhancement of ascorbate content with the soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 was 40.4 and 28.4 per cent during 2019-20 and 32.0 and 30.9 per cent during 2020-21, respectively, and proline content was 25.4 and 19.3 per cent during 2019-20 and, 23.2 and 18.1 per cent during 2020-21, respectively. Especially under water stress, the treatment that received the Glomus mosseae @ 12.5 kg ha-1 exhibited superior performance and increased the ascorbate and proline contents by 38.1 and 37.5 per cent during 2019-20 and 56.0 and 31.2 per cent during 2020-21, respectively. While, the treatment that received Gigaspora sps. @ 12.5 kg ha-1 increased the ascorbate and proline contents by 46.7 and 27.4 per cent during 2019-20 and 50.0 and 23.9 per cent during 2020-21, respectively. Both under irrigated and water stress conditions, Acaulospora sps. @ 12.5 kg ha-1 exhibited poor performance and recorded lesser increase in antioxidant metabolites compared to all other mycorrhizae.
Antioxidant enzymes i.e., superoxide dismutase and catalase activities were significantly increased in the groundnut plants under water stress by 130.0 and 59.9 per cent during 2019-20 and 102.5 and 53.0 per cent during 2020-21, respectively compared to those under irrigated condition. Soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 recorded higher SOD and catalase activities both under irrigated as well as drought stress conditions. Especially under water stress, Glomus mosseae exhibited superior performance by increasing SOD and catalase activities by 134.1 and 28.3 per cent during 2019-20 and 93.7 and 36.4 per cent during 2020-21, respectively. While, Gigaspora sps. enhanced the SOD and catalase activities by 126.1 and 25.1 per cent, and 87.4 and 22.9 per cent in both the years, respectively.
The uptake of macro and micro nutrients was declined under water stress. Nitrogen and phosphorus uptake of groundnut crop grown under water stress was reduced by 41.0 and 29.9 per cent during 2019-20, and 46.2 and 35.9 per cent during 2020-21 compared to control without stress at 60 DAS. Among the sub treatments, groundnut plants inoculated with Glomus mosseae increased the nitrogen uptake by 59.9 and 71.4 per cent, phosphorus uptake by 41.3 and 70.8 per cent and potassium uptake by 40.6 and 19.1 per cent during 2019-20 and 2020-21, respectively. While, Gigaspora sps. inoculation increased the nitrogen, phosphorus and potassium uptake by 50.0, 27.6 and 22.3 per cent during 2019-20, and 62.8, 49.0 and 16.4 per cent during 2020-21. Nitrogen uptake of groundnut plants inoculated with Glomus mosseae (68.3 and 94.4 %) and Gigaspora sps. (47.2 and 82.2 %) was significantly higher than control under stress. Similarly, phosphorus uptake was significantly increased with Glomus mosseae (33.9 and 57.1 %) and Gigaspora sps. (26.8 and 55.5 %) under water stress.
Similarly, soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 enhanced the potassium, calcium, magnesium, sulphur, iron, copper, manganese and zinc uptake compared to other mycorrhizal treatments under irrigated and water stress conditions in both the years. Non-mycorrhizal plants recorded lower nutrient
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uptake and the groundnut plants inoculated with Acaulospora sps. and Glomus aggregatum @ 12.5 kg ha-1 recorded poor performance in enhancing nutrient uptake of groundnut.
Water stress reduced the yield attributes viz., number of pods per plant by 37.2 and 39.5 per cent, peg to pod ratio by 39.7 and 32.8 per cent, pod yield of groundnut by 32.0 and 33.5 per cent, and harvest index by 5.2 and 11.2 per cent during 2019-20 and 2020-21, respectively. Among the sub treatments, soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 enhanced the yield and yield attributes significantly compared to other treatments. Number of pods per plant were enhanced by 23.0 and 22.9 per cent during 2019-20 and 33.4 and 29.7 per cent during 2020-21 by the inoculation of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1, respectively, compared to non-mycorrhizal plants. While, the pod yield was enhanced by 26.4 and 25.2 per cent during 2019-20 and 28.9 and 25.5 per cent during 2020-21 by the inoculation of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1, respectively. Irrigated groundnut plants inoculated with Glomus mosseae @ 12.5 kg ha-1 increased the pod yield by 15.8 and 21.4 per cent during 2019-20 and 2020-21, respectively, while, Gigaspora sps. @ 12.5 kg ha-1 enhanced the pod yield by 17.2 and 23.2 per cent, respectively compared to control under irrigation in both the years. Glomus mosseae and Gigaspora sps. exhibited superior performance under water stress also by increasing the number of pods per plant by 47.5 and 46.4 per cent and 38.5 and 29.4 per cent during 2019-20 and 2020-21, respectively, and the pod yield by 44.3 and 38.9 per cent during 2019-20, and 40.9 and 29.2 per cent during 2020-21. Soil application of Acaulospora sps. was recorded with lower number of pods per plant, peg to pod ratio and pod yield under irrigated and water stress condition.
The VAM colonization per cent of the groundnut roots subjected to water stress was 32.7 and 34.8 per cent lower than the plants under irrigated condition. The higher root colonization was observed in treatments that received the soil application of Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 which recorded 69.00 and 68.33 per cent, respectively, during 2019-20 and 66.50 and 66.00 per cent, respectively, during 2020-21 at 60 DAS. Under drought stress, higher root colonization was noticed with the soil application of Glomus mosseae @ 12.5 kg ha-1 (57.00 and 52.33 %) followed by Gigaspora sps. (54.33 and 49.67 %) during 2019-20 and 2020-21, respectively, while, control under drought stress was recorded with the lowest root colonization (7.33 and 7.33 %) in both the years, respectively.
With regards to available soil nutrient content, except nitrogen and phosphorus no significant differences were observed with the application of mycorrhiza. The higher available soil nitrogen content after harvest was recorded in the treatment without mycorrhizal inoculation while, lower nutrient content was observed in the treatment that received Glomus mosseae @ 12.5 kg ha-1 during 2019-20 and in the treatment that received Gigaspora sps. @ 12.5 kg ha-1 during 2020-21. It was found to be on a par with all other mycorrhizal treatments except control i.e., no mycorrhizal application, and the available soil phosphorus content after harvest was higher in non-mycorrhizal plants and lower in the treatment that received the soil application of Glomus fasciculatum @ 12.5 kg ha-1 during 2019-20 and 2020-21 and it was found to be on a par with other mycorrhizal treatments except control.
It is evident from the present study, water stress during pegging and pod formation stages had harmful effect on growth, pod yield, nutrient uptake and water status of groundnut plants. AM colonization improved the drought resistance and
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nutrient uptake of groundnut plants as a consequence of enhanced water and nutritional status (both macro and micro nutrients) of the plants. Our results clearly illustrate that Glomus mosseae and Gigaspora sps. were the most effective AM species which improved the growth and yield of groundnut plants both under irrigated as well as water stress conditions. Especially under water stress condition, inoculation of groundnut plants with Glomus mosseae and Gigaspora sps. @ 12.5 kg ha-1 improved the growth and yield of the plants due to the improvement of water relations, nutrient content, gas exchange status, photosynthetic pigments and antioxidant defense system which could protect the groundnut plants against the deleterious effects of drought stress.