Drought stress is becoming a structural phenomenon in cropping systems challenged by climate change and soil fertility degradation. A balanced fertilization strategy based on nitrogen, phosphorus, and potassium as well as on silicon supplementation was tested as an efficient practice to improve maize tolerance to short-term drought stress. Three fertilization strategies (control: treatment with zero NPK fertilizer application; NPK: granular NPK fertilizer, and NPK + Si: granular NPK fertilizer enriched with 5% silicon) were evaluated under three irrigation regimes simulating three probable water deficit levels in the Mediterranean climate (I1, well-watered conditions: 80% of soil field capacity; I2, medium drought stress: 60% of soil field capacity; and I3, severe drought stress: 30% of soil field capacity). Drought stress was applied at V10 growth stage of maize and maintained for 15 days, then plants were rewatered according to the optimal irrigation regime. Results showed that medium and severe drought stress down-regulated maize plant growth and yield, especially under nutrient deficient conditions (control). Plants amended with NPK and NPK + Si recorded higher chlorophyll a pigment content (+ 22 to + 64%), stomatal conductance (+ 6 to 24%), and leaf relative water content (+ 7 to 23%) than those of the control, depending on the drought stress level. Silicon supplementation attenuated the down-regulation effects of drought stress on maize photosynthesis and biomass accumulation by improving stomatal conductance and electron transfer efficiency between PSII and PSI. Silicon supply improved the performance index for energy conservation from photons absorbed by PSII to the reduction of intersystem electron acceptors (PIabs) and reduced the dissipation energy flux (DIo/RC), responsible for the protection of PSII from photo-damage under drought stress, which resulted in significant enhancement of maize photosynthesis recovery and grain yield (+ 59 to 69%). Findings from the present study demonstrate that granular NPK-fertilizer fortified with silicon could be an efficient strategy to increase maize photosynthesis performance, plant growth, and productivity under short-term drought stress conditions.

Silicon, a quasi-essential nutrient element, is well known for imparting tolerance to various biotic and abiotic stresses in crops. The experiments were carried out to evaluate the effect of orthosilicic acid (a silicon source) with two methods of application viz., soil drenching and foliar application against phloem feeders under field conditions for two seasons on two different black gram cultivars. Among the cultivars, Vikral responded better to orthosilicic acid than Pratap Urd 1 regarding the reduction of the population of phloem feeders and enhancement of defense enzyme activity, silicon uptake, total sugars, and total phenols and yield in both the seasons. Among the application methods, soil drenching (2 mLL(-1)) proved to be the superior method of administration to record a significantly low population of phloem feeders, increased activity of defense enzymes, total sugars, and total phenols content, improved activity of coccinellids and yield in both seasons. However, it holds good with the foliar application (2 mLL(-1)) method. Both the application methods were significantly superior to insecticidal check and untreated control treatments. Deposition of silicon was highest in the leaves of black gram (1.541%) when orthosilicic acid was administered through soil than foliar (1.451%) and untreated control (0.891% endogenously available silicon). The highest benefit: cost ratio recorded in soil drenching of orthosilicic acid @ 2 mLL(-1) (1.88 and 1.93) surpassed the B: C ratio of recommended insecticidal check (1.65 and 1.72) during winter and summer seasons, respectively. Both the application methods of orthosilicic acid proved significantly superior over insecticidal check with respect to the management of phloem feeders in black gram including enhanced grain yield, coccinellids activity, and induced biochemical defense as well as the lowest cost of cultivation, which can be easily incorporated with other practices for eco-friendly, sustainable management of phloem feeders in black gram.