Heterosis for dry matter and protein production per plant in diploperennial teosinte-maize hybrids

As we have previously reported (MNL 61:63, 198 7), the heterosis produced in interspecific hybrids between diploperennial teosinte (Zea diploperennis) and a sweet variety of maize (Ever-green) can be detected in an early stage through the quantitation of the same traits during the earlier developmental stages of the younger plants. The results previously obtained and some other results obtained subsequently have let us make a most complete study through which the greater biologic efficiency of these hybrids can be demonstrated.

As was previously pointed out, this experiment let us obtain information about dry matter and protein production per plant in these hybrids and their respective parents. The different measurements were taken from seeding throughout the first 30 days of growing. The data obtained were used to calculate dry weight per plant (DW/PL) and protein per plant (P/PL). The increase in dry weight per plant (DW/PL) and protein per plant (P/PL) was evaluated on the basis of initial dry weight and protein in seeds respectively. The mean growth rate (MGR) expressed in mg of dry weight/plant day and the mean protein production rate (MPPR) expressed in mg of protein/plant day, were evaluated on the basis of the initial values for both traits. The results obtained are illustrated in Figures 1 to 4.

Table 1. Heterosis of diploperennial teosinte maize hybrids for the expression of the following traits: dry weight per plant (DW/PL), protein per plant (P/PL), dry weight increase per plant (DWI/PL) and protein increase per plant (PI/PL).
 
 
% heterosis respect
Character Mid parent Better parent
DW/PL (.g) 136.1 60.2
P/PL (mg) 110.2 57.6
DWI/PL (mg) 176.4 89.1
PI/PL (mg) 134.6 88.4

 

As can be seen, hybrids are remarkably better than their parents when we analyze dry weight and protein production per plant. Thirty days after sowing, the hybrids had produced almost 2 times more dry weight and protein content than the better parent (maize). The greater efficiency of these hybrids to express the measured traits is mainly a direct consequence of both a high mean growth rate and protein production rate during the period we have considered.

The heterosis expressed by those considered traits (see Table 1) is not only high when it is calculated in relation in the mid-parent, but also when it is evaluated in relation to the better parent (maize).

Finally we can say that though maize can be considered as one of the most efficient vegetable species the results we have obtained show that this particularity could probably be increased through the utilization of wild germplasm.

Figure 1. Variation of dry weight per plant (DW/PL) expressed in mg in Ever-green maize (Eg), diploperennial teosinte (Zd) and its hybrids (Zd x Eg).

Figure 2. Variation of protein content per plant (P/PL) expressed in mg in Ever-green maize (Eg), diploperennial teosinte (Zd) and its hybrids (Zd x Eg).

Figure 3. Variation of mean growth rate (MGR) expressed in mg dry weight/plant - day in Ever-green maize (Eg), diploperennial teosinte (Zd) and its hybrids (Zd X Eg).

Figure 4. Variation of mean protein production rate (MPPR) expressed in mg protein/plant - day in Ever-green maize (Eg), diploperennial teosinte (Zd) and its hybrids (Zd x Eg).

Ida G. Palacios and Jorge M. Magoja


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