Effect Of Parching-field On Yield And Physio-Ecological Characteristics Of Early And Late Dual Purpose Super Rice In South China

This experiment was conducted to investigate optimal parching-field mode of early and late dual purpose super rice in South China during tillering stage and physio-ecological mechanism of yield formation. Field experiment was carried out in SCAU farm in 2014 and 2015 with a main popularized super rice in guangdong province—Yuxiangyouzhan. Two parching-field degrees — moderate drought(the average relative soil water content reach about 60%±5% at 0~20cm soil layer)and severe drought(the average relative soil water content reach about 40%±5% at 0~20cm soil layer)—were set respectively while the tiller number reached to two different stages(70% and 80%tillerings of preformed spike number). Changes of rice physiological and growth characteristics under different parch stages and degrees and rehydration during tillering stage had been systematically studied, meanwhile, its physio-ecological mechanisms were analysed too. We hope to provide theoretical basis of high productivity and efficiency cultivation for early and late dual purpose super rice in South China. The main results are as follows:Moderate parch degree could increase effective panicle and spike rate, that was beneficial to promote final yield and yield components. W1 and W2's effective panicle number and spike rate showed large increment than CK in two years. Final yield was about11.24% higher than CK in early rice, 8.95% higher than CK in later rice.Parching-field treatment decreased the net photosynthetic rate and transpiration rate during the treatment period, restrictd rice growth in tillering stage, reduced dry matter accumulation during processing. Due to compensation effect after rehydration, at jointing stage of 2015 early rice, W2's(while tillering mumber reached about 80% preformed spike number with moderate parch treatment) net photosynthetic rate was significantly higherthan CK(maintain 1cm water layer during tillering stage), each treatment of 2015 later rice was increased by 11.75%~17.14% than CK. Accelerated growth after rehydration reasonably adjusted dry matter distribution dynamics during the whole growth stage, which promoted single stem growth. LAI and chloroplast pigment content from full heading stage to maturity stage were higher than CK, which was conducive to the improvement of photosynthetic rate and dry matter accumulation in the later growth stage, thereby increasing the dry matter accumulation account for the proportion of the whole growth period, improved spike rate and final yield.Parching-field treatment could increase the content of antioxidant enzymes activities and osmotic adjustment substances in Yuxiangyouzhan during treatment stage. Each treatments' SOD activity maintained high levels at jointing stage, which were22.66%~48.61% higher than CK at jointing stage in 2015 early rice. POD and CAT activities reached the highest at the end of treatment, only part of the treatments were higher than CK at jointing stage. Leaf proline content performed an upward trend during treatment stages, but decrease at jointing stage in two early rice seasons. Leaf proline contents remained higher than CK in 2014 later rice, W1 and W2 treatments showed the optimal performance than others in 2014 early rice and 2015 later rice.Parching-field treatment improved field aeration conditions, expand the soil temperature difference, the average soil temperature at 5cm depth expand 1 ~ 2 ? than CK.Moderate drought, the average relative soil water content reach about 60%±5% at0~20cm soil layer or parching-field for 5~7 days when soil surface became dry and tight and not sticky, at tillering stage was the best parching-field management mode. Under this mode, yield was higher than CK and quality kept good.