• Energy Research

In the coastal zone of the Ganges Delta, water shortages due to soil salinity limit the yield of dry season crops. To alleviate water shortage as a consequence of salinity stress in the coastal saline ecosystem, the effect of different water-saving (WS) and water-conserving options was assessed on growth, yield and water use of tomato; two field experiments were carried out at Gosaba, West Bengal, India in consecutive seasons during the winter of 2016–17 and 2017–18. The experiment was laid out in a randomized block design with five treatments viz., surface irrigation, surface irrigation + straw mulching, drip irrigation at 100% reference evapotranspiration (ET0), drip irrigation at 80% ET0, drip irrigation at 80% ET0 + straw mulching. Application of drip irrigation at 80% ET0 + straw mulching brought about significantly the highest fruit as well as the marketable yield of tomato (Solanum lycopersicum L.). The soil reaction (pH), post-harvest organic carbon, nitrogen, phosphorus and potassium (N, P and K) status and soil microbial population along with the biochemical quality parameters of tomato (juice pH, ascorbic acid, total soluble solids and sugar content of fruits) were significantly influenced by combined application of drip irrigation and straw mulching. Surface irrigation significantly increased the salinity level in surface and sub-surface soil layers while the least salinity development was observed in surface mulched plots receiving irrigation water through drip irrigation. The highest water productivity was also improved from drip irrigation at 80% ET0 + straw mulched plots irrespective of the year of experimentation. Such intervention also helped in reducing salinity stress for the tomato crop. Thus, straw mulching along with drip irrigation at 80% ET0 can be recommended as the most suitable irrigation option for tomato crop in the study area as well as coastal saline regions of South Asia. Finally, it can be concluded that the judicious application of irrigation water not only increased growth, yield and quality tomatoes but also minimized the negative impact of soil salinity on tomatoes grown in the coastal saline ecosystem of Ganges Delta.

In the coastal zone of the Ganges Delta, water shortages due to soil salinity limit the yield of dry season crops. To alleviate water shortage as a consequence of salinity stress in the coastal saline ecosystem, the effect of different water-saving (WS) and water-conserving options was assessed on growth, yield and water use of tomato; two field experiments were carried out at Gosaba, West Bengal, India in consecutive seasons during the winter of 2016–17 and 2017–18. The experiment was laid out in a randomized block design with five treatments viz., surface irrigation, surface irrigation + straw mulching, drip irrigation at 100% reference evapotranspiration (ET0), drip irrigation at 80% ET0, drip irrigation at 80% ET0 + straw mulching. Application of drip irrigation at 80% ET0 + straw mulching brought about significantly the highest fruit as well as the marketable yield of tomato (Solanum lycopersicum L.). The soil reaction (pH), post-harvest organic carbon, nitrogen, phosphorus and potassium (N, P and K) status and soil microbial population along with the biochemical quality parameters of tomato (juice pH, ascorbic acid, total soluble solids and sugar content of fruits) were significantly influenced by combined application of drip irrigation and straw mulching. Surface irrigation significantly increased the salinity level in surface and sub-surface soil layers while the least salinity development was observed in surface mulched plots receiving irrigation water through drip irrigation. The highest water productivity was also improved from drip irrigation at 80% ET0 + straw mulched plots irrespective of the year of experimentation. Such intervention also helped in reducing salinity stress for the tomato crop. Thus, straw mulching along with drip irrigation at 80% ET0 can be recommended as the most suitable irrigation option for tomato crop in the study area as well as coastal saline regions of South Asia. Finally, it can be concluded that the judicious application of irrigation water not only increased growth, yield and quality tomatoes but also minimized the negative impact of soil salinity on tomatoes grown in the coastal saline ecosystem of Ganges Delta.

Tea tree oil (TTO) from the genus Melaleuca L. has antimicrobial, antibacterial, antifungal, and antioxidant properties and is used by the cosmetic, pharmaceutical, and horticultural industries. In Pakistan, Melaleuca bracteata can be exploited for essential oil purposes, as this species is well adapted to Pakistan’s agroclimatic conditions. The objective of the present study was to evaluate the yield of M. bracteata essential oil together with its antioxidant and antimicrobial properties under local prevailing conditions of the subtropics. Essential oil was extracted through the hydrodistillation method. Using this method, six batches of 8 kg samples (fresh leaves and branches) underwent a distillation process for 4–5 h. The average yield obtained was about 0.2%. The GCMS was used to identify the components of extracted essential oil. Eugenol methyl ether is the major component in extracted essential oil, i.e., 96% of the total. A high content of flavonoids and phenolics and a Fe-reducing power ability of M. bracteata were observed. The oil was also found effective against B. subtilis, B. cereus, White rot, and A. flavus. Hence, it is concluded that there is a possibility to use TTO for its biocidal properties, and it must also be inspected and then commercialized in Pakistan by the agriculture and cosmetic industries.

Tea tree oil (TTO) from the genus Melaleuca L. has antimicrobial, antibacterial, antifungal, and antioxidant properties and is used by the cosmetic, pharmaceutical, and horticultural industries. In Pakistan, Melaleuca bracteata can be exploited for essential oil purposes, as this species is well adapted to Pakistan’s agroclimatic conditions. The objective of the present study was to evaluate the yield of M. bracteata essential oil together with its antioxidant and antimicrobial properties under local prevailing conditions of the subtropics. Essential oil was extracted through the hydrodistillation method. Using this method, six batches of 8 kg samples (fresh leaves and branches) underwent a distillation process for 4–5 h. The average yield obtained was about 0.2%. The GCMS was used to identify the components of extracted essential oil. Eugenol methyl ether is the major component in extracted essential oil, i.e., 96% of the total. A high content of flavonoids and phenolics and a Fe-reducing power ability of M. bracteata were observed. The oil was also found effective against B. subtilis, B. cereus, White rot, and A. flavus. Hence, it is concluded that there is a possibility to use TTO for its biocidal properties, and it must also be inspected and then commercialized in Pakistan by the agriculture and cosmetic industries.

Sustainable increases in crop production require efficient use of resources, and intercropping can improve water use efficiency and land productivity at reduced inputs. Thus, in a three-year field experiment, the performance of maize/soybean strip intercropping system differing with maize plant density (6 maize plants m-2, low, D1; 8 maize plants m-2, medium, D2; and 10 maize plants m-2, high, D3) was evaluated in comparison with sole maize or soybean cropping system. Results revealed that among all intercropping treatments, D2 had a significantly higher total leaf area index (maize LAI + soybean LAI; 8.2), total dry matter production (maize dry matter + soybean dry matter; 361.5 g plant-1), and total grain yield (maize grain yield + soybean grain yield; 10122.5 kg ha-1) than D1 and D3, and also higher than sole maize (4.8, 338.7 g plant-1, and 9553.7 kg ha-1) and sole soybean (4.6, 64.8 g plant-1, and 1559.5 kg ha-1). The intercropped maize was more efficient in utilizing the radiation and water, with a radiation use efficiency of 3.5, 5.2, and 4.3 g MJ-1 and water use efficiency of 14.3, 16.2, and 13.3 kg ha-1 mm-1, while that of intercropped soybean was 2.5, 2.1, and 1.8 g MJ-1 and 2.1, 1.9, and 1.5 kg ha-1 mm-1 in D1, D2, and D3, respectively. In intercropping, the land and water equivalent ratios ranged from 1.22 to 1.55, demonstrating that it is a sustainable strategy to improve land and water use efficiencies; this maximization is likely associated with the species complementarities for radiation, water, and land in time and space, which resulted in part from competition avoidance responses that maximize the economic profit (e. g., 1300 US $ ha-1 in D2) over sole maize (798 US $ ha-1) or sole soybean (703 US $ ha-1). Overall, these results indicate that optimizing strip intercropping systems can save 20–50% of water and land, especially under the present scenario of limited resources and climate change. However, further research is required to fully understand the resource capture mechanisms of intercrops in intercropping.

Sustainable increases in crop production require efficient use of resources, and intercropping can improve water use efficiency and land productivity at reduced inputs. Thus, in a three-year field experiment, the performance of maize/soybean strip intercropping system differing with maize plant density (6 maize plants m-2, low, D1; 8 maize plants m-2, medium, D2; and 10 maize plants m-2, high, D3) was evaluated in comparison with sole maize or soybean cropping system. Results revealed that among all intercropping treatments, D2 had a significantly higher total leaf area index (maize LAI + soybean LAI; 8.2), total dry matter production (maize dry matter + soybean dry matter; 361.5 g plant-1), and total grain yield (maize grain yield + soybean grain yield; 10122.5 kg ha-1) than D1 and D3, and also higher than sole maize (4.8, 338.7 g plant-1, and 9553.7 kg ha-1) and sole soybean (4.6, 64.8 g plant-1, and 1559.5 kg ha-1). The intercropped maize was more efficient in utilizing the radiation and water, with a radiation use efficiency of 3.5, 5.2, and 4.3 g MJ-1 and water use efficiency of 14.3, 16.2, and 13.3 kg ha-1 mm-1, while that of intercropped soybean was 2.5, 2.1, and 1.8 g MJ-1 and 2.1, 1.9, and 1.5 kg ha-1 mm-1 in D1, D2, and D3, respectively. In intercropping, the land and water equivalent ratios ranged from 1.22 to 1.55, demonstrating that it is a sustainable strategy to improve land and water use efficiencies; this maximization is likely associated with the species complementarities for radiation, water, and land in time and space, which resulted in part from competition avoidance responses that maximize the economic profit (e. g., 1300 US $ ha-1 in D2) over sole maize (798 US $ ha-1) or sole soybean (703 US $ ha-1). Overall, these results indicate that optimizing strip intercropping systems can save 20–50% of water and land, especially under the present scenario of limited resources and climate change. However, further research is required to fully understand the resource capture mechanisms of intercrops in intercropping.

Livestock development in rainfed areas is slower due to the inadequate supply of nutritious fodder. Mono-cropping systems also have a negative impact on forage yield and nutrition as cereals are deficient in protein. Hence, there is a dire need to grow cereals with legumes to improve forage yield and quality. Therefore, a two-year field study was undertaken to evaluate winter cereal–legume forage and their mixtures viz. oats (cv. PD2-LV65), barley (Jau-86) and one legume viz. vetch (cv. Languedock) under different tillage systems viz. conventional tillage (moldboard plow+4-cultivation with tines) and conservation tillage (3-cultivation with tines). Crops were grown in pure stands as well as in mixtures with a 70:30 seeding ratio. The results revealed that the conventional tillage system performed better in terms of numbers of tillers/branches, leaf-to-stem ratio and green fodder yield than the conservation tillage system. However, the conventional and conservation tillage systems did not show a significant difference in terms of crude protein, acid detergent fiber and neutral detergent fiber. In the pure stands and cereal–legume mixtures, the oat–vetch mixture performed better in terms of plant height, leaf-to-stem ratio and green fodder yield. The maximum crude protein content was observed in the oat–vetch mixture, while the maximum acid detergent fiber and neutral detergent fiber were observed in the pure oat stands. In competitive indices, the land-equivalent ratio and competitive ratio showed the advantage of intercropping. In actual yield loss, results showed the positive value of barley and oats in mixtures, which reflects the advantage of intercropping in the rainfed areas. The economic analysis showed a greater net benefit from the conventional tillage than the conservation tillage system under rainfed conditions. On the basis of this investigation, an oat–vetch mixture and the conventional tillage system are recommended for higher tonnage of nutritious fodder in rainfed areas.