Groundnut is an annual legume and important oilseed crop in the world. In order to evaluate the influence of the topping height and application methods of Zinc (Zn) and Calcium (Ca) nano-chelates on quantitative and qualitative characteristics of groundnut, these experiments were carried out during the 2016–2017 cropping seasons on groundnut in Iran. Both foliar and in soil applications of Zn and Ca nano-chelates improved groundnut yield. Foliar application of Zn nano-chelate in combination with topping the main stem 20 cm above the ground produced the highest 100-seed weight (82.19 g), seed yield per unit area (2722.5 kg.h⁻¹), harvest index (57.53%), biological yield (6540.00 kg.h⁻¹), oil yield (1486.76 kg.h⁻¹), protein yield (742.66 kg.h⁻¹), seed Zn content (12.08 ppm) and Ca content (35.86 ppm). The application of Zn nano-chelate had different positive influences on vegetative and reproductive growth of groundnut plants. Generally, optimizing of the nutritional status in groundnut plants with Ca and Zn supplements is recommended to enhance the quantitative and qualitative yield of groundnut.

Intercropping between cereals and legumes can increase resource use efficiency, agricultural productivity, and yield sustainability and reduce chemical inputs. For these reasons, this experiment was performed as factorial arrangement based on randomized complete block design with three replications in experimental station of Guilan Agricultural and Natural Resources Research and Education Center, Rasht, Iran in 2016 and 2017 cropping seasons. Experimental treatments included five levels of phosphorus fertilizer (PF) as triple super phosphate (TSP) including : 1- Zero (as control), 2–50 kg ha-1 TSP, 3–100 kg ha-1 TSP, 4–50 kg ha-1 TSP+200 g ha-1 Barvar2 phosphate bio-fertilizer (BPB) and 5–100 kg ha-1 TSP+200 g ha-1 BPB, and five IPs (IP) including: 1- maize (Zea mays L.) sole cropping, 2- groundnut sole cropping, 3- intercropped groundnut-maize with the ratio of 1:1, 2:1 and 1:2 rows, . Although, maximum grain yield of maize and groundnut was obtained in response to the application of 100 kg ha-1 TSP plus 200 g ha-1 BPB under sole cropping, the highest land equivalent ratio (LER) was observed under zero usage of TSP and intercropped maize-groundnut with the ratio of 1:1 rows. Crops in intercropping system have a complementary effect together. In this experiment, LER values greater than 1.00 indicated an intercrop advantage to sole crop. Results showed that IP increases the quantity and quality of products by increment in plant diversity, ecological balance, more utilization of resources, and reduction of damage by pests, diseases, and weeds in agricultural ecosystems.

This study was conducted to investigate the effects of salicylic acid and harvest date on the yield and biochemical and physiological characteristics of peanuts in different humidity conditions, which is the novelty of this research. For this purpose, a split-plot factorial design during the 2018 and 2019 cropping seasons was conducted based on a randomized complete block design with three replications at the experimental field of the Agricultural and Natural Resources Research and Education Center of Guilan Province, Astara, Iran. Humidity regimes included rain-fed conditions (no irrigation), irrigation at the 10% flowering stage, 10% pod formation stage, and 10% flowering stage +10% pod formation stage in the main plots, and three salicylic acid levels (100, 200, and 300 µmol/l), and harvest dates (August 22, September 6, and September 21), were placed in subplots. Drought stress reduced the Chlorophyll Index, relative water content, seed, and pod yield but increased proline, Antioxidant enzyme activity, soluble sugar content, and H₂O₂content. Conversely, Supplementary irrigation decreased proline, antioxidant enzyme activity, soluble sugar content, and H₂O₂content, which increased the Chlorophyll Index, relative water content, seed, and pod yield. Also, salicylic acid foliar application enhanced guaiacol peroxidase, polyphenol oxidase, and ascorbate peroxidase antioxidant enzyme activity, mitigating the undesirable impacts of water deficiency. The maximum pod and seed production was obtained in all humidity conditions with 300 µmol/l salicylic acid. Under Humidity stress conditions, if water resources are available, two supplementary irrigations at 10% flowering and 10% pod formation stage are recommended. Also, for humid climates such as Astara and similar regions, in terms of climate, with limited rainfall in June and July (rainfall less than 10 mm during flowering and podding stages), one supplementary irrigation at 10% pod formation stage is recommended.