For the prediction of jojoba seedling sex before flowering, some leaf
shape parameters and indices were measured and calculated from known sex
population of jojoba. Leaf shape indices included the basic parameters of leaf blade
length (L), blade width at its one-fourth point from the base (W1), blade width at its
widest region rNO) and the blade width at its three-fourth point from the base (W2) in
addition to six suggested derived ratios which included: LfWO, W1/L, WO/L, W21L,
2W1/L and 2W2/3L. It was statistically found that only six out of the 10 selected leaf
parameters could be used for the identification of jojoba seedling sex (L, W2, WO, W1,
W1/L and 2W~/L). The standard values of leaf parameters of jojoba shrubs indicated
the possibility of using leaf morphological parameters to identify male and female
jojoba plants. Preflowering sex identification was carried out using three methods: 1- Preflowering sex identification by the confidence limits comparisons; the confidence
limits of the different leaf parameters of the standard known sex jojoba shrubs
were first calculated, data of the unknown seedlings were compared with the
confidence limits of the standard known sex population. Generally, it was found
that the different leaf parameters were able to identify the seedling sex of a limited
portion of the population size, not more than 21.52% in the case of 2W1/L. 2- Preflowering sex identification by the overall mean comparisons; Since the means
of males were always smaller than females, the seedling mean of any parameter
was compared to the corresponding standard overall mean of that parameter. It
was generally found that the different leaf parameters were able to identify
successfully the sex of about 53% (W1/L) to almost 66% (W1) of the unknown
population of jojoba seedlings. 3- Preflowering sex identification by the multiple separation method; it was possible by
using the multiple separation method to identify accurately and high reliably the
sex of 70 unknown jojoba seedlings (44.30% of the tested population), 22 males
and 48 females. Finally It can be strongly recommended to use the overall mean
comparisons not only due to its extremely easy way of calculations but also to the
highly accurate results of sex identification as well as the high percentage of identified
seedlings obtained.