Abstract
In recent decades, agricultural practices have shifted from diverse cropping systems to monocropping, leading to soil degradation, nutrient depletion, and reduced biodiversity, which threaten long-term productivity and ecosystem sustainability. This study aimed to explore how legume cultivar selection influences pea (Pisum sativum L.)-wheat (Triticum aestivum L.) intercropping, focusing on symbiotic nitrogen (N) fixation, yield, seed N, and land productivity. A greenhouse experiment was conducted using various pea cultivars that were released in different decades [Century (1960), Trapper (1970), CDC Golden (2002), CDC Amarillo (2012), and CDC Spectrum (2016)] under monocropping and intercropping with wheat to evaluate the yield parameters and symbiotic N fixation capabilities of pea. The old, long-vined pea cultivars (Century and Trapper) had higher seed dry weight (62.9-66.3%), number of pods (82.7-100%) and number of seeds (126.9-163.5%) than the newer, moderate vine length cultivars (CDC Golden, CDC Amarillo and CDC Spectrum) under intercropping. On the other hand, the companion wheat crop had a greater yield (29.8-69.9%) and seed N (31.1-65.5%) when intercropped with the newer pea cultivars. Intercropping enhanced N fixation (0.7-7.5%) in peas across cultivars; however, the older cultivars contributed more to the overall system's N fixation and N carry-over compared to the newer cultivars. While the harvest index, land equivalent ratio (LER), and N-based LER (LERN) of intercropped wheat were not significantly higher than mono-cropped wheat, the increased partial LER and LERN for wheat highlight intercropping benefits. Overall, newer pea cultivars enhanced pea-wheat intercropping by improving productivity and resource efficiency, highlighting the importance of legume cultivar selection in intercropping.