Plant spacing modulates growth, yield and nutrient dynamics of sponge gourd under semi-arid conditions.

With the global population steadily rising and arable land shrinking, enhancing per-unit area productivity has become a critical challenge, particularly in semi-arid regions where resource limitations further constrain crop yields. Sponge gourd (Luffa aegyptiaca L.), a nutrient-rich summer vegetable, often underperforms in such environments due to unoptimized planting geometry. This two-year field study evaluated the influence of intra-row spacing (1 ft vs. 2 ft) on the vegetative growth, reproductive traits, chlorophyll fluorescence, and nutrient uptake of sponge gourd cv. Advanta, grown in sandy loam soils of Southern Punjab, Pakistan. Closer spacing (1 ft) significantly improved germination by 8.1%, seedling vigor index by 15.9%, plant height by 12%, leaf area index by 58.3%, and crop growth rate by 79.8% compared to wider spacing. It also increased female flower percentage (18.1%), flower diameter (21.4%), fruit set (31.4%), fruit diameter (20.8%), and fruits per plant (55%). Consequently, fruit yield was about 28.1% higher under 1 ft spacing. Nitrogen and phosphorus uptake increased by 12.2% and 19.2%, respectively, with corresponding improvements in nutrient uptake efficiency. In contrast, wider spacing (2 ft) enhanced photosynthetic performance, with increases in quantum yield (9%) and linear electron flow (3.5%). In conclusion, closer intra-row spacing is a practical strategy to meet future food demands by maximizing land use efficiency in cucurbit cultivation. Future work should investigate spacing-nutrient interactions over multiple locations to ensure sustainability in closer intra-row spacing systems.