Unveiling the effect of foliar applied siliceous compounds on reducing seed shattering for the conservation of endangered kalmegh (Andrographis paniculata (Burm. f.) wall. ex nees)

Abstract

This investigation was conducted to formulate a cost-efficient and dependable technique for the extensive regeneration of the Kalmegh plant, focusing on the challenge of seed shattering during the harvesting process. Across a biennial time frame spanning from 2022 to 2023, diverse siliceous substances were administered through foliar application to address seed-shattering issues and enhance growth parameters. The study was carried out utilizing a Randomized Complete Block Design (RCBD) involving seven treatments and 3 replications. The experimental site is situated in a semi-arid sub-tropical region known for hot summers and comparatively mild winters. Results revealed that the foliar application of potassium silicate at a concentration of 200 mg/L notably boosted plant height (42.86 cm), plant spread (19.68 cm²), root length (14.87 cm), and leaf dimensions (4.51 cm) compared to alternative treatments. Furthermore, the application of potassium silicate at 200 mg/L substantially decreased the number of shattered pods (262), while elevating the count of intact pods (91.23), overall pod tally (524.3), and seeds per plant (4718). Increased silicon levels were detected in capsules, suggesting a heightened silicon deposition in plant tissues after the utilization of siliceous substances. Principal component analysis and correlation assessments were utilized to evaluate the impacts of treatments and the interrelationships among variables. To distinguish treatment variations, PCA was performed on a total of eight parameters and six treatments. Together, PC-1 and PC-2 explained 96.14 % of the variance, with PC-1 accounting for 88.83 % and PC-2 for 7.31 %. Plant height is separated by PC-1; T2 shows negative loading, but the other variables and treatments show positive loading. The number of shattered seeds/pod is the main determinant of PC-2; T7 exhibits negative loading, whilst other seeds show positive loading. The links between shattered and unshattered pods, as well as other variables including plant height, plant spread, leaf size, and root length, regarding the use of siliceous compounds were investigated using correlation analysis. The study highlights the effectiveness of applying siliceous compounds via foliar approaches to augment Kalmegh seed productivity and growth attributes in an environmentally sustainable manner, thereby aiding in meeting the escalating demand for this significant medicinal plant.