Identification and Validation of Cold Tolerant Maize Zea mays L Genotypes for High Altitude Conditions of Kashmir Valley

Abstract

newline Cold stress poses a significant challenge to maize (Zea mays L.) production in high-altitude regions, limiting growth, yield, and overall crop resilience. This study aimed to identify genetically superior inbreds with enhanced cold tolerance. Conducted over two growing seasons (2022 2023 and 2023 2024), the research evaluated 164 maize inbreds under both field and controlled greenhouse conditions to assess their response to low-temperature stress. Comprehensive morpho-physiological and agronomic evaluations revealed significant genetic variability among the genotypes. Germination rates varied widely (10% 100%), reflecting differential stress adaptation. Substantial variation was observed in root traits, chlorophyll content, grain yield, and total dry matter weight, all critical indicators of cold resilience. Based on stress response, inbreds were classified into highly tolerant (7), tolerant (16), moderately tolerant (93), susceptible (42), and highly susceptible categories (6). High broad-sense heritability (gt60%) was recorded for essential traits such as grain yield per plant (95.14%), total dry matter weight (90.97%), chlorophyll content (85.73%), and root weight (92.78%), confirming strong genetic control and potential for selection. Correlation and principal component analyses highlighted key traits like newlineflowering synchrony, robust root architecture, and physiological stability as pivotal for cold tolerance improvement. Biochemical profiling of 24 contrasting inbreds provided further insights into stress adaptation mechanisms. Significant variations were observed in protein content (7.58% 12.69%), resistant starch (0.71% 7.60%), and total soluble sugars (8.79% 60.51%). A strong positive correlation between soluble sugars and cold tolerance suggests their role in osmotic regulation and metabolic stability under low temperatures, further supporting their significance in stress adaptation. Molecular validation of ten cold tolerance associated SSR markers identified seven polymorphic markers,