Corm ecotype and cultivation location modulate the magnitude of Bacillus sp. strain D5 mediated enhancement of saffron yield and quality

Abstract This is the first comprehensive multivariate analysis evaluating the effects of a Bacillus sp. strain D5 (Bar D5) based bioformulation on soil fertility and growth performance of saffron across traditional and non-traditional cultivation zones using two ecotypes. Corms of two saffron ecotypes, from Kashmir (Km) and Kishtwar (Kw), were primed with a Bar D5 based bioformulation and cultivated at Pulwama, the traditional site and Mandi, the non-traditional site. The interactive effects of the bioformulation, cultivation location and ecotype were evaluated on vegetative growth, flowering, stigma yield and quality, soil physicochemical properties, rhizospheric bacilli dynamics, and field persistence of Bar D5. Bar D5 treatment significantly enhanced flowering, stigma biomass and quality parameters, along with vegetative traits including shoot length, root length and number, leaf number, and daughter corm weight. Although the number of shoots and daughter corms reduced after Bar D5 treatment, individual corm weight increased, suggesting improved resource allocation towards vegetative and reproductive potential. Notably, at the non-traditional site, Bar D5 primed corms produced stigmas with quality comparable to those from the traditional site. Soil health parameters, including nitrogen, phosphorus, potassium, organic carbon, and calcium content, improved significantly at both locations. Principal component and Pearson correlation analyses revealed the potential of the Bar D5 bioformulation to enhance saffron productivity and quality in the non-traditional region. However, treatment effects were modulated by cultivation location and ecotype. The Kashmir ecotype showed greater phenotypic stability than the Kishtwar ecotype. Among the two locations, the effect of Bar D5 was more pronounced at Mandi where clearer differentiation between ecotype responses was observed.