Multivariate diagnosis of nutrient element norms for grape

Abstract

The multivariate compositional nutrient element diagnosis (CND) and the critical values for the indices were developed for Anab‐e‐Shahi cultivar of grape during bud differentiation and flowering stages. The CND values for all the nutrient elements, except for potassium (K), were higher during bud differentiation stage (BDS) compared to the flowering stage (FS) reflecting greater requirement of nutrient elements during bud initiation and differentiation in grapes. The principal component analysis (PCA) was used to extract correlation structure among the nutrient elements in the high‐yielding population. The four principal components (PCS) explaining 74.1% of the total variance at BDS were designated as [nitrogen (N)+K+calcium (Ca)+magnesium (Mg)+sulfur (S)‐iron (Fe)+manganese (Mn)‐zinc (Zn)], (N+P‐Ca‐Mg‐Zn‐), (K‐S+Mn‐) and (P+Ca+Fe‐). The two PCS explaining about 70% of the variance at FS were designated as (P+K+Ca+Mg+S‐Mn‐) and (N‐P‐S‐Fe+). The Euclidian distance (d) computed from the PCS provided nutrient element imbalance index for the crop. The d value showed significant negative correlation with yield (‐0.327*) at BDS, while no significant relationship could be established at FS. The critical values for indices (I values) was lower for S, Fe, and Zn at BDS and higher for N, P, K, Ca, Mg, and Mn at FS.