Effects Of Sowing Date And Planting Density On Growth, Yield And Quality In Saline-alkali Soil Peanut

The experiment was carried on field in Maotuo village, Tingluo town, Lijin county, Dongying City, from April to October in the year 2014. The peanut cultivar ‘Huayu 25’ was used as material. Plant growth, leaf photosynthesis, physiological characteristics, yield and quality of saline-alkali soil planted peanut were analyzed in the present study under different sowing dates and densities. Results were shown as follows: 1 Effects of sowing date and planting density on plant growth of saline-alkali soil planted peanutWith the delay of sowing date, growth period of peanut plant was shorter. The growth periods of peanut plant sown on April 25 and June 9 were 147 days and 112 days, respectively. The largest effect of sowing date on peanut growth was at flowering-pod filling stage when there was a gap of 16 days between the longest and the shortest growth periods.It showed obviously different in plant height and length of branches under different sowing densities. With the increase of planting density, the plant height and length of branches showed changes with first increasing and decreasing later. Under single seed planting mode with the density of 235 thousand holes per hm2, the plant height and length of branches were the largest of 23.00 cm and 29.00 cm, respectively. And the lowest in plant height and length of branches were 19.43 cm and 26.08 cm, respectively, when the planting density was reduced to 180 thousand holes per hm2. Under double seed planting mode, the largest in plant height and length of branches were 19.43 cm and 26.08 cm, respectively, with planting density of 130 thousand holes per hm2. While, the lowest were shown under 116 thousand holes per hm2 with 17.13 cm in plant height and 20.18 cm in length of branches. On the whole, both plant height and length of branches showed higher under single seed planting mode than double seed planting mode with the same plant number per unit. 2 Effect of sowing date on leaf physiological characteristics, leaf photosynthesis and photosyntheticfluorescence parametersWith the delay of sowing date, it showed the trend of increase first and then decrease in leaf chlorophyll content, Pn, Tr, ΦPSⅡ, Fv/Fm, SOD, POD and CAT with the except of MDA which showed opposite trend. Leaf chlorophyll content, Pn, ΦPSⅡ and Fv/Fm showed higher under the sowing dates on May 5, May 10 and May 15 than under other sowing dates. The highest in leaf chlorophyll content and Pn were 2.17 mg·g-1 and 26.04 μmol·m-2·s-1, respectively, when seeds were sown on dates May 5. And the lowest were 1.92 mg·g-1 and 23.04 μmol·m-2·s-1, respectively, when sown on April 25. Tr and SOD activity were higher on sowing dates of May 5, May 10 and May 15 than on other sowing dates, while MDA decreased significantly. POD and CAT showed significantly high when seeds were sown on May 5 3 Effects of sowing date and planting density on peanut yield and quality in saline alkali soilWith the delay of sowing date, pod yield showed first increase and then decrease. The highest yield was 5360.10 kg·hm-2 when seeds were sown in May 5th, which showed increase by 42.02% and 106.23% in early sowing April 25 and late sowing June 9, respectively. The increase of 100 pod weight, 100 kernel weight and kernel rate and the decrease of pod number per kg were the reason for yield increase. With the delay of sowing date, the soluble sugar content and protein content of peanut kernel increased while fat content decreased, which was significantly different among the sowing dates.With the increase of planting density, pod yield showed first increased and then decreased. Under both the single seed and double seed planting modes, there were significant differences among different treatments. The highest yield were 5403.26 and 4324.80 kg·hm-2 in the density of 235 thousand holes per hm2 and 130 thousand holes per hm2, respectively. The lowest yield were 3159.90 and 2857.95 kg·hm-2 in the density of 180 thousand holes per hm2 and 116 thousand holes per hm2. With the same plant number per unit, the pod yield under the single seed planting mode was higher than that under double seed planting mode. The effect of planting density on peanut quality showed no difference. 4 Effects of planting density on peanut dry matter accumulation and distribution in saline alkali soilWith the increasing of planting density, the maximum growth rate of leaves and stems(Vm) showed a trend of first increase and then decrease. The highest Vm of leaves and stems was in the density of 235 thousand holes per hm2 while the lowest was in density of 180 thousand holes per hm2. For the double seed planting mode, the highest Vm was 0.2868 in density of 116 thousand holes·hm2, while the lowest was 0.2268 in density of 130 thousand holes per hm2. The time(Tm) for maximum growth rate of leaves and stems was affected by planting density. Under single seed planting mode, the maximum growth rate of either leaves or stems showed the earliest in density of 235 thousand holes per hm2, with the pod distribution rate was up to 38.10%, while the lowest pod distribution rate was 35.63% in density of 180 thousand holes per hm2. Under double seed planting mode, the largest pod distribution rate was up to 34.40% in density of 147.13 thousand holes per hm2 while the loweat was 31.24% in density of 116 thousand holes per hm2. With the same plant number per unit, the Vm and the pod distribution rate under single seed planting mode was higher than those under double seed planting mode.