Exogenous GABA application helps muskmelon seedlings absorb and use nitrogen better when stressed with Ca(NO3)2. The study showed that under this stress, certain enzymes related to nitrogen absorption were affected, leading to a decrease in nitrate and an increase in ammonia levels in the plants. However, applying GABA improved the absorption of nitrate and helped in the assimilation of ammonia, promoting plant growth. GABA also helped in regulating enzyme activities related to amino acid metabolism and increased the accumulation of endogenous GABA, making the seedlings more resistant to Ca(NO3)2 stress.