Abstract Plant growth promoting rhizobacteria increase plant growth and give protection against insect pests and pathogens. Due to the negative impact of chemical pesticides on environment, alternatives to these chemicals are needed. In this scenario, the biological methods of pest control offer an eco-friendly and an attractive option. In this study, the effect of two plant growth promoting rhizobacterial strains (Bacillus sp. strain 6 and Pseudomonas sp. strain 6K) on aphid population and wheat productivity was evaluated in an aphid susceptible (Pasban-90) and resistant (Inqlab-91) wheat cultivar. The seeds were inoculated with each PGPR strain, separately or the combination of both. The lowest aphid population (2.1 tiller−1), and highest plant height (85.8 cm), number of spikelets per spike (18), grains per spike (44), productive tillers (320 m−2), straw yield (8.6 Mg ha−1), and grain yield (4.8 Mg ha−1) were achieved when seeds were inoculated with Bacillus sp. strain 6 + Pseudomonas sp. strain 6K. The grain yield of both varieties was enhanced by 35.5–38.9% with seed inoculation with both bacterial strains. Thus, the combine use of both PGPR strains viz. Bacillus sp. strain 6 + Pseudomonas sp. strain 6K offers an attractive option to reduce aphid population tied with better wheat productivity.

Under rainfed conditions, farmers rarely use micro-nutrients for crop production, due to which soils become deficient especially in zinc (Zn) and boron (B). Secondly, farmers apply nutrients through soil application but scarcity/less availability of moisture make the nutrients unavailable for crop plants. Under such circumstances, foliar application of Zn and B may play a key role for better crop growth and yield. Therefore this field study was conducted to investigate the role of Zn and B application alone and in combination through seed, soil and foliar application methods on growth, yield and net returns of maize grown under rainfed conditions. Results showed that combined application of Zn and B on foliage improved relative water contents, SPAD chlorophyll values, leaf area index (LAI), crop growth rate (CGR), and grain yield due to substantial expansion in entire yield related traits. Combined foliar application of Zn and B harvested 12% and 45% more yield compared with seed priming and control treatments, respectively. The foliar application of Zn and B in combination counteracted the low rainfall effect by producing higher relative water contents that helped in improving SPAD-chlorophyll values, LAI and CGR. Higher net returns and benefit: cost ratio was also obtained by foliar application of Zn and B in combination. In conclusion, combined foliar application of B and Zn improved maize yield due to significant expansion in allometric and yield related traits and thus improved net returns of maize grown under rainfed conditions of Pothwar plateu in Pakistan.

Salinity is the leading abiotic stress hampering maize (Zea maysL.) growth throughout the world, especially in Pakistan. During salinity stress, the endogenous ethylene level in plants increases, which retards proper root growth and consequent shoot growth of the plants. However, certain bacteria contain the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase, which converts 1-aminocyclopropane-1-carboxylic acid (an immediate precursor of ethylene biosynthesis in higher plants) into ammonia and α-ketobutyrate instead of ethylene. In the present study, two Pseudomonas bacterial strains containing ACC-deaminase were tested separately and in combinations with mineral fertilizers to determine their potential to minimize/undo the effects of salinity on maize plants grown under saline-sodic field conditions. The data recorded at 30, 50 and 70 days after sowing revealed that both the Pseudomonas bacterial strains improved root and shoot length, root and shoot fresh weight, and root and shoot dry weight up to 34, 43, 35, 71, 55 and 68%, respectively, when applied without chemical fertilizers: these parameter were enhanced up to 108, 95, 100, 131, 100 and 198%, respectively, when the strains were applied along with chemical fertilizers. It can be concluded that ACC-deaminase Pseudomonas bacterial strains applied alone and in conjunction with mineral fertilizers improved the root and shoot growth of maize seedlings grown in saline-sodic soil.

Optimum planting methods better ensure water and nutrient supply through improved root development resulting in better crop growth and productivity. This study was conducted to evaluate the effects of planting methods on root development, crop allometry, water use efficiency (WUE), productivity and economic returns of different maize (Zea mays L.) hybrids. Maize hybrids NK-6621, Pioneer-30Y87, and Pioneer-30Y58 were sown on beds, ridges, and flat surface. Ridge sowing was better followed by bed sowing; while amongst the hybrids, ’Pioneer-30Y87’ performed the best. Well-developed root system, with longer primary root, more number of lateral roots and higher root growth rate, was observed in ’Pioneer-30Y87’ planted on ridges, which led to higher WUE, grain yield and its related traits. The same hybrid exhibited higher leaf area index and crop growth rate, and maximum net return and benefit:cost ratio sowed on ridges. Overall, the ridge sowing improved root development resulting in better allometry, productivity (5.45 t ha-1), and WUE (1.345 kg m-3), in all the maize hybrids. Although maize hybrids exhibited different response to different planting methods; maximum grain yield (5.63 t ha-1), WUE (1.41 kg m-3), and net economic returns were observed from hybrid Pioneer-30Y87.

Métodos óptimos de siembra aseguran mejor suministro de agua y nutrientes a través del mejorado desarrollo de raíces que resulta en mejor crecimiento y productividad de los cultivos. Este estudio se realizó para evaluar los efectos de los métodos de siembra en el desarrollo de las raíces, alometría de cultivos, uso eficiente del agua (WUE), productividad y rentabilidad económica de diferentes híbridos de maíz (Zea mays L.). Híbridos de maíz NK-6621, Pioneer 30Y87, y 30Y58-Pioneer se sembraron en camas, surcos, y superficie plana. La siembra en surco fue mejor, seguida por siembra en cama, mientras entre los híbridos, ’Pioneer 30Y87’ tuvo los mejores resultados. Se observó un sistema radical bien desarrollado, raíz primaria más larga, mayor número de raíces laterales, y mayor tasa de crecimiento radical, en ’Pioneer-30Y87’ plantado en surcos, lo que condujo a mayores WUE, rendimiento de grano y sus rasgos relacionados. El mismo híbrido sembrado en surcos presentó mayores índice de área foliar y tasa de crecimiento del cultivo, máximo rendimiento neto y relación beneficio:costo. En general, la siembra en surco mejoró el desarrollo radical resultando en mejores alometría, productividad (5,45 t ha-1), y WUE (1,35 kg m-3), en todos los híbridos de maíz. Aunque los híbridos de maíz mostraron respuesta diferente a los diferentes métodos de siembra, máximos rendimientos de grano (5,63 t ha-1), WUE (1,41 kg m-3), y retornos económicos netos se observaron en el híbrido Pioneer 30Y87.