Cowpea and kidney bean plants were grown in a hydroponic system, and the effect of calcium silicate supplied to the nutrient solution under salt stress was investigated. The plants were subjected to four different treatments: (1) nutrient solution alone (C), (2) nutrient solution + 40 mmol l )1 NaCl (NaCl), (3) nutrient solution + 40 mmol l )1 NaCl + 0.5 mmol l )1 CaSiO 3 (NaCl + Si 1 ) and (4) nutrient solution + 40 mmol l )1 NaCl+1 mmol l )1 CaSiO 3 (NaCl + Si 2 ). The results showed that, in both species, salinity reduced all growth variables but silicate supplementation however partly overcame this growth reduction. Addition of silicate in NaCl-stressed plants maintained membrane permeability. Net photosynthesis, chlorophyll content, stomatal conductance and transpiration were higher in plants under control treatment, and the inclusion of silicate in the nutrient solution resulted in a slight increase in these plant parameters. Intercellular CO 2 was slightly higher in plants under silicate treatment than in plants under control or NaCl treatment. Calcium concentration in shoots and roots in both species was slightly higher in the treatments where silicate was added. Potassium concentration for salt treatment was reduced in shoot and root of both species in the absence of silicate. Sodium and chloride concentration in shoots and roots in both species were slightly higher in the presence of NaCl and were slightly reduced in the plants under silicate treatments. The results suggest that, in hydroponically grown plants, the inclusion of silicate in the nutrient solution is beneficial because it improves growth, physiological parameters and may contribute to a more balanced nutrition by enhancing nutrient uptake under NaCl-stressed conditions. Added calcium silicate may ameliorate the parameters affected by high salinity, may reduce sodium and chloride, and can slightly increase calcium and potassium concentrations in shoots and roots of salt-stressed cowpea and kidney bean.

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The objective of the present study was to evaluate the annual ovulatory activity of hair sheep at 15° N. Nineteen Creole ewes with body weight of 40.8 ± 0.3 kg were used. The ovulatory activity was monitored for a year by quantifying progesterone concentrations in blood samples obtained from all the ewes every 7 days. The differences in monthly proportions of ewes with ovulatory activity were analyzed by the chi-square test. Ovulatory activity decreased from May to July and in September, and 42% of ewes ovulated year round. It is concluded that at 15° N, a high proportion of ewes is capable of ovulating throughout the year in the tropical southeastern region of Mexico.

Little is known about the productive performance of Mexican turkey, so the objective of the present study was to characterize growth performance curves of backyard turkey under a confined system. Forty fertile eggs were artificially incubated and turkey weight was recorded at hatch. During growth performance weekly weight was measured until 385 days of age. Turkey commercial feed and water were offered ad libitum. To characterize growth curves, a fourth degree polynomial model regression and a Richards biological model were used, which were compared by determination coefficient (r 2), to reach the best fit model. The best fit model was the fourth degree polynomial regression model from a mathematical standpoint of view. It was found that maximum tom growth was reached at 15.7 weeks with a weight gain of 259.3 g/week and in hens at 12.4 weeks with a weight gain of 112.0 g/week. Body weight reached by toms at 40 weeks was 6 kg and hens at 35 weeks with 3.6 kg.