Germinação, crescimento e desenvolvimento de genótipos de mamoneira irrigados com águas salinas.

Abstract

The objective of the present study was to observe the effects of the different water salinity levels in the castor genotype {Ricinus conmunis L.), from the germination to the production. The experiment was conducted in Federal University of Campina Grande under greenhouse condutions, a random design was used with forty five treatments using five salinity levels (SL) of the irrigation water, in terms of electrical conductivity expressed as (ECW: SLi- 0.7; SL2- 2.7; SL3 - 4.7; SL4 - 6.7; SL5 - 8.7 dS m"1 at 25°C) with three castor cultivars Paraguacu 1, Paraguacu 2 e CSRN- 367, with three repetitions. The irrigation waters were prepared adding NaCl to get the desired (ECW). According to results obtained it can be concluded that the germination rates of Paraguacu 2 was less then the others at EC„ 8.7 dS m"1 besides, increasing by five days the number of days to germinate, presenting a decrease of 4.25% for unit increment of ECW. The CSRN-367 presented an increment of 8.91% at 2.7 dS m"1 compared to 0.7 dS m"1 for the emergency velocity index. In the growth and development phase, it was observed that the salinity affected the vegetative development of the plants, 80 days after sowing. Between 0.7 and 8.7 dS m"1 the plant height of the Paraguacu 1 reduced 92.56%, between 0.7 and 6.7 dS m"1 the number of leaves of Paraguacu 2 reduced 60.76%, in relation for leaf area the reduction was 78.73% in case of CSRN - 367; similar results were also observed in the production with an increase of the ECW, 45 days after sowing occurred the flowering in CSRN-367 under 0.7 dS m"1, as it presented the longest bunch height, higher precocity in the crop of the fruits and greater number of fruits up to 4.7 dS m"1 ECW. The fruits and seeds weight of all cultivars were similar, but 10 seeds of Paraguacu 1 and 2 were heavier than CSRN-367 at 0.7 and 2.7 dS m"1 ECW. Between trataments as compared to 0.7 dS m"1 76 - 90 days after sowing the daily water consumption decreased 85% in 6.7 dS m"1 ECW. The cultivars survived until 80 days at 8.7 dS m"1 ECW. According to the results, it can be concluded that the water till 2.7 dS m"1 ECW can be used to irrigate castor reaching its best results at the lowest ECW.