Statistics for Chicory (Cichorium intybus) and plantain (Plantago lanceolata); physiological and morphological responses to water stress, defoliation, and grazing preference with implications for the management of the Herb and Legume Mix : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science, Massey University, Te Kunenga ki Pūrehuroa, New Zealand