Morphological, chemical and in vitro traits for prediction of stover quality in pearl millet for use in multidimensional crop improvement

The paper reports on the variations in organic matter digestibility (OMD), organic matter intake (OMI), digestible organic matter intake (DOMI) and nitrogen (N) balances of 40 pearl millet stover fed to sheep ad libitum and investigated relationships between these in vivo variables and morphological, chemical and in vitro stover quality traits. Highly significant differences (P<0.0001) were observed for all in vivo variables. Plant height and stem diameter were consistently significantly (at least P=0.0002) inversely related to OMD, OMI, DOMI and N balance. Except for OMD (P=0.16) stover nitrogen content was significantly (at least P=0.0005) positively related to OMI, DOMI and N balance. The fiber constituents neutral (NDF) and acid (ADF) detergent fiber and acid detergent lignin (ADL) were consistently inversely related to OMD, OMI, DOMI and N balance. (at least P=0.0005). Stover in vitro digestibility, metabolizable energy content and extent and rate of in vitro gas production were highly positively (at least P<0.0009) related to the in vivo variables while lag and half time of in vitro gas production were negatively associated (at least P=0.0004) with the in vivo variables. Combined morphological, chemical and in vitro variables in stepwise multiple regressions accounted for 70 to 84%% of the variations observed in the in vivo variables. Application of stringent cross validation procedures reduced the variation in OMD, OMI, DOMI and N balance accounted for by the combined morphological, chemical and in vitro variables mostly moderately to 71, 49, 79 and 76%, respectively. Relatively simple traits can predict stover quality in breeding programs for dual-purpose pearl millet cultivars