Morphological Measures of Earliness of Crop Maturity in Cotton¹

Abstract

Certain features of the gross morphology of the cotton plant furnish clues to earliness of crop production. Three such features — (1) node of first fruiting branch (NFB), (2) number of vegetative branches (NVB), and (3) percentage of bolls on vegetative branches (PBV) — were used as morphological measures of earliness in the studies reported here. All of the morphological measures were significantly correlated but, because of its higher heritability and lower variability, NFB is considered the most reliable and the most practical one of the three. NFB and NVB were signficantly correlated, phenotypically, with product‐quantity measures of earliness. Mean maturity date (MMD), a product‐quantity measure, and NFB, a morphological measure, are separate estimates of the same phenomenon: i.e., earliness of crop maturity. Used together, they are mutually supporting and they form a reliable basis for estimating earliness in genetic studies and breeding programs.