Productivity enhancement of vegetables through salt stree mitigation in the sandy loam soils of Onattukara

Abstract

The study entitled “Productivity enhancement of vegetables through salt stress mitigation in the sandy loam soils of Onattukara” was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2022-2024. The main objective of the study was to evaluate the ameliorative effect of calcium silicate and supplementary foliar nutrition on growth and mineral nutrition of vegetables in the salt stressed areas of Onattukara using tomato as the test crop. The three parts of the study were the development of multinutrient formulation for supplementary foliar nutrition, germination test for identifying the critical level of salinity for tomato and the evaluation of the effect of calcium silicate and supplementary foliar nutrition on growth and mineral nutrition of vegetables under salt stress. The salient research findings emanated from the experiments are summarized below. A multi nutrient formulation containing K, Ca, Mg, N, B and Zn was developed for supplementary foliar nutrition based on general soil status. General soil status of these nutrients was low and literature references and adhoc recommendations for secondary and micronutrient management and information on crop requirement were also used for developing the formulation. Suitable nutrient carriers were used for developing the foliar formulation. The carriers evaluated to prepare the mixture were KNO3, CaNO3, MgSO4. 7H2O, H3BO3, ZnSO4.7H2O, Na2B8O13. 4H2O and Zinc acetate. Humic acid and potassium silicate were used as surfactant and binder materials. Based on the properties like pH, EC and solubility in water and trial on standing crop, the mixture containing KNO3, Ca (NO3)2, MgSO4.7H2O, Boric acid and ZnSO4.7H2O was found to be the best. This formulation had a nutrient composition of K (10%), N (4%), Ca (6%), Mg (2.5%), B (5%) and Zn (2%) and recorded a pH of 6.32 and EC of 0.6dSm-1, which was within the desirable limit for foliar formulations and was 100% soluble. The germination test for identifying the critical level of salinity for tomato was carried out in the laboratory in completely randomized design using seeds of tomato variety

Vellayani vijai. Different levels of salinity (10mM, 20mM, 30mM, 40mM of NaCl) was evaluated along with control and critical level of salinity for tomato identified. Observations taken on the 14th day of experiment showed that the germination percentage of tomato seeds reduced from 96.52% to 30.87% , days needed to complete germination increased from 3.70 days to 12.15 days and root shoot dry weight ratio increased from 0.433 to 0.611 with an increase in salinity levels from 0mM NaCl (T1) to 40mM NaCl (T5). The analysis of Na and K content of tomato seedlings also revealed a significant increasing trend in Na+/ K+ ratio of shoot and root with increase in salinity levels. Na+/ K+ ratio of shoot ranged from 2.23 to 4.21 and Na+/ K+ ratio of root ranged from 1.90 to 3.36 with treatments T1 to T5. The germination study could identify the treatment T4 - Hoagland solution containing 30 mM NaCl which recorded a noticeably greater reduction in germination percentage (<80%) as the critical level of salinity for tomato. Hence 30 mM NaCl and 40 mM NaCl were selected for the pot culture experiment. The pot culture experiment was conducted from January to April 2024 at O.R.A.R.S., Kayamkulam using tomato (var. Vellayani vijai) as the test crop to evaluate the effect of various doses of calcium silicate (100 kg ha-1 to 150 kg ha-1) and supplementary foliar nutrition (0.5%) on growth and mineral nutrition of vegetables under salt stress. Biometric observations like plant height, number of branches, fruit set percentage and internodal length were significantly higher in the treatment T7 ( Soil test based POP + CaSiO3 @ 125 kg ha-1 + 0.5 % spray of multi nutrient mixture @ 30 mM salt stress) whereas days to first fruit set, root length, root volume and root dry weight was higher in treatment T8 ( Soil test based POP + CaSiO3 @ 150 kg ha-1 + 0.5 % spray of multi nutrient mixture @ 30 mM salt stress). Treatments containing calcium silicate and supplementary foliar nutrition showed a significant improvement in all of the biometric observations recorded. With regard to the yield attributes such as fruits per plant, fruit weight and yield per plant, the treatment T7 ( Soil test based POP + CaSiO3 @ 125 kg ha-1 + 0.5 % spray of

The study entitled “Productivity enhancement of vegetables through salt stress mitigation in the sandy loam soils of Onattukara” was carried out at the Department of Soil Science and Agricultural Chemistry, College of Agriculture, Vellayani during 2022-2024. The main objective of the study was to evaluate the ameliorative effect of calcium silicate and supplementary foliar nutrition on growth and mineral nutrition of vegetables in the salt stressed areas of Onattukara using tomato as the test crop. The three parts of the study were the development of multinutrient formulation for supplementary foliar nutrition, germination test for identifying the critical level of salinity for tomato and the evaluation of the effect of calcium silicate and supplementary foliar nutrition on growth and mineral nutrition of vegetables under salt stress. The salient research findings emanated from the experiments are summarized below. A multi nutrient formulation containing K, Ca, Mg, N, B and Zn was developed for supplementary foliar nutrition based on general soil status. General soil status of these nutrients was low and literature references and adhoc recommendations for secondary and micronutrient management and information on crop requirement were also used for developing the formulation. Suitable nutrient carriers were used for developing the foliar formulation. The carriers evaluated to prepare the mixture were KNO3, CaNO3, MgSO4. 7H2O, H3BO3, ZnSO4.7H2O, Na2B8O13. 4H2O and Zinc acetate. Humic acid and potassium silicate were used as surfactant and binder materials. Based on the properties like pH, EC and solubility in water and trial on standing crop, the mixture containing KNO3, Ca (NO3)2, MgSO4.7H2O, Boric acid and ZnSO4.7H2O was found to be the best. This formulation had a nutrient composition of K (10%), N (4%), Ca (6%), Mg (2.5%), B (5%) and Zn (2%) and recorded a pH of 6.32 and EC of 0.6dSm-1, which was within the desirable limit for foliar formulations and was 100% soluble. The germination test for identifying the critical level of salinity for tomato was carried out in the laboratory in completely randomized design using seeds of tomato variety

Vellayani vijai. Different levels of salinity (10mM, 20mM, 30mM, 40mM of NaCl) was evaluated along with control and critical level of salinity for tomato identified. Observations taken on the 14th day of experiment showed that the germination percentage of tomato seeds reduced from 96.52% to 30.87% , days needed to complete germination increased from 3.70 days to 12.15 days and root shoot dry weight ratio increased from 0.433 to 0.611 with an increase in salinity levels from 0mM NaCl (T1) to 40mM NaCl (T5). The analysis of Na and K content of tomato seedlings also revealed a significant increasing trend in Na+/ K+ ratio of shoot and root with increase in salinity levels. Na+/ K+ ratio of shoot ranged from 2.23 to 4.21 and Na+/ K+ ratio of root ranged from 1.90 to 3.36 with treatments T1 to T5. The germination study could identify the treatment T4 - Hoagland solution containing 30 mM NaCl which recorded a noticeably greater reduction in germination percentage (<80%) as the critical level of salinity for tomato. Hence 30 mM NaCl and 40 mM NaCl were selected for the pot culture experiment. The pot culture experiment was conducted from January to April 2024 at O.R.A.R.S., Kayamkulam using tomato (var. Vellayani vijai) as the test crop to evaluate the effect of various doses of calcium silicate (100 kg ha-1 to 150 kg ha-1) and supplementary foliar nutrition (0.5%) on growth and mineral nutrition of vegetables under salt stress. Biometric observations like plant height, number of branches, fruit set percentage and internodal length were significantly higher in the treatment T7 ( Soil test based POP + CaSiO3 @ 125 kg ha-1 + 0.5 % spray of multi nutrient mixture @ 30 mM salt stress) whereas days to first fruit set, root length, root volume and root dry weight was higher in treatment T8 ( Soil test based POP + CaSiO3 @ 150 kg ha-1 + 0.5 % spray of multi nutrient mixture @ 30 mM salt stress). Treatments containing calcium silicate and supplementary foliar nutrition showed a significant improvement in all of the biometric observations recorded.