Effects Of Planting Patterns And Irrigation Amount On Radiation Use Efficiency Of Winter Wheat

The experiment was conducted during the growing season of winter wheat(Triticum aestivum L.) in Shandong Agricultural University Agronomy Experimental Station(36°09’ N, 117°09’ E) from 2013 to 2014. A total of 27 experimental plots(each 3 m × 3 m in size) were established with the same plant population density of 200 × 104 plants ha-1. Three planting patterns were used: single-single row(SS), single-double row(SD) and double- double row(DD); Three irrigation amount treatments were used: 0, 90, and 180 mm; 0, 30, 60 mm of water were applied at jointing stage, heading stage and filling stage respectively. In order to develop a water-conserving planting pattern for winter wheat grown in the North China Plain, canopy structure and the photosynthetic characteristics of flag leaves was investigated. The results were as follows:1. Population develop dynamics The stem number of SD was larger and its descent speed was faster, but the stem number of DD was less and its descent speed was lower at the earlier growth stage. The SD(D) and DD planting patterns were in favour of slowing down the fluctuation ranges of LAI and maintaining high green leaf function period. The narrow row spacing and expand plant distance can construct reasonable population develop dynamics of winter wheat, coordinate the relationship between group and individual, reduce the competition of resource, improve the population LAI, thus beneficial to the accumulation of dry matter. Irrigation amount could increase the LAI of winter wheat and narrow the differences among the planting patterns in the stem number and LAI. The influences of planting patterns to the stem number(before winter, jointing stage and heading stage) and LAI(setting stage and flag stage) were greater; the influences of irrigation amount to the LAI at filling stage were greater.2. Canopy photosynthetic active radiation The DD planting pattern could reduce the light leak, improve the population structure of winter wheat and reduce significantly the PAR penetration ratio, thus increased the PAR capture ratio of winter wheat. The PAR reflection ratio were identical with PAR penetration ratio, and the order of them was SS > SD > DD. The narrow row spacing and expand plant distance can increase the bottom PAR capture ratio, improve the canopy PAR capture ratio, thus improved the yield of winter wheat. The irrigation amount increased canopy PAR capture ratio of winter wheat, and there was not significant difference of capture ratio between 90 mm and 180 mm irrigation amount treatment. The 180 mm treatment was greatest for the PAR capture ratio of above the ground 40 cm and 0 mm treatment could in favour of improve the PAR capture ratio of above the ground 0-40 cm. The order of daily PAR capture ratio at heading stage and filling stage was DD > SD > SS, and the advantage of DD was obvious at 12:00. So the DD planting pattern can provide the basis for photosynthesis. The order of PAR capture ratio was 180 mm > 90 mm > 0 mm, and especially at 12:00. Irrigation amount decreased the difference among plating patterns in the canopy PAR capture ratio and different height PAR capture ratio, and their differences were obvious at the combination of 0 mm and DD planting pattern. The effect of irrigation amount on the PAR penetration ratio was greater at flower stage than other growth stages.3. Leaf physiological characteristics The CCI and Pn of SD(D) and DD planting patterns sustained at a higher level in the whole growth stage, and the rate of descent were lower, so contributing to extend the blade of the leaf function period. The rule of Ci, Tr and Cond was presented that the DD planting pattern were highest and rate of descent were lower, thus DD maintained a high level at the late growth stage. The CCI, Pn, Ci, Tr and Cond increased with incresing the irrigation amount. The irrigation amount could improve the growth of winter wheat and slow the decline of CCI and Pn at the same time, so that was contributing to maintaing at a higher level. Irrigating 90 mm can slow the descend range of Ci, Tr, Cond and contributing to maintaining stability at the late growth stage of winter wheat. The gap of CCI among planting patterns was lager with 90 mm irrigation amount and narrowed the difference among plating patterns in the Pn, Ci, Tr, Cond. The advantage of CCI was obvious at the combination of irrigating 90 mm and DD. And the advantage of Pn, Ci, Tr, Cond were obvious at the combination of irrigating 0 mm and DD. The obvious advantages of DD among leaf physiological characteristics were as follows: the Pn at 10:00 of heading stage and 16:00 of milking stage, the Tr at 10:00 of heading stage and 14:00 of milking stage, the Cond at 10:00 of heading stage and 12:00 of milking stage, the Ci at 14:00 of heading stage and 16:00 of milking stage. Besides, the obvious advantages of increasing irrigation amount among leaf physiological characteristics were as follows: the Pn at 10:00 of heading stage and 16:00 of milking stage, the Cond at 10:00 of heading stage and milking stage, the Ci at 12:00 of heading stage and 16:00 of milking stage.4. Root growth characteristics The root diameter averages of SS were higher than others at all growth stages and were slower in the soil layer of 0-20 cm than thoses of other planting patterns, so the advantage of SS was obvious in 0-20 cm soil layer. But the effect of DD on the root diameter averages was obvious in 0-20 cm soil layer. The length in sample, root density and fresh root weight of DD were higher, and the root-shoot ratio was lower than those of other planting patterns, and they were falling slower. So, narrow row spacing and expand plant distance can improve the drought resistance performance of winter wheat at the late growth stage. The root system mainly concentrated in the shallow soil layer under the normal conditions of soil moisture. Irrigation amount can change the spatial distribution of winter wheat root system. Deficit irrigation increased the averages root diameter, length in sample, root density in 20-40 cm soil layer, and providing a stable foundation for improving the grain yield. Moderate drought in winter and reasonable irrigation in spring were contributing to the development of root growth after seedling. Irrigation amount could decrease the difference among planting pattern to the averages root diameter, root density in 0-20 cm soil layer, and increase them in 20-40 cm soil layer. The length in sample of DD increased with the increasing amount. The advantage of fresh root weight was obvious in combination irrigating 0 mm with DD.5. Dry matter accumulation and distribution The DD planting pattern not only improves significantly the total dry matter accumulation, but also adjusts reasonable the allocation amount of different organs. The NAR of SS and SD(S) maintained at a higher level, but the increased range of SD(D) and DD were larger, so narrow row space and expand plant distance can improve the NAR of the late growth stage. Irrigating 90 mm was beneficial to the accumulation and distribution of dry matter. The NAR increased with the increasing irrigation amount, the advantage of NAR was the obvious under the condition of irrigating 90 mm and SS. The influence of the planting pattern on NAR at jointing stage was great and the irrigation amount to the NAR at filling stage was great.6. Determination of grain quality The DD planting pattern reduces dough development time and improves wet gluten content and falling number significantly. Thus improve the processing quality. Farinograph, wet gluten content, gulten index and falling number were affected significantly by irrigation amount. Irrigating 90 mm was beneficial to the Farinograph and wet gluten content. There was no significant difference between farinograph with the increase of the irrigation amount.The gulten index and Pasting temperature of 180 mm irrigation amount was higher. Irrigating 90 mm was beneficial to the flour viscosity traits of winter wheat.7. The relationship between yield and yield components, yield and photosynthetic factors Narrow row space and expand plant distance was in favor of improving spikes, grains, thousand grain weight, spike length, spikelet number, grain yield, harvest index and RUE; The spikes, grains, thousand grain weight, plant height, spike length, spikelet number, grain yield, stem and leaf dry matter and RUE increased with the increasing amount. Irrigation amount can decrease the difference of yield component among planting patterns. The influences of planting pattern on harvest index were obvious. The influences of irrigation amount on spikes, grains, thousand grain weight, plant height, spike length, spikelet number, stem and leaf dry matter were obvious. The yield components(except the sterile spikelet number) and photosynthetic factors(except Fv/Fm and LAI) have a role in promoting the grain yield. The interaction between the photosynthetic factors(except Fv/Fm and PAR capture ratio, LAI and PAR capture ratio) improved significantly the grain yield of winter wheat. The order of effecting on grain yield was spikelet number > plant height > spike length > grains > thousand grain weight > spikes, and the photosynthetic factors was PAR capture ratio > Pn > CCI > Ci > LAI > Fv/Fm; Choosing the plant height, spike length, spikes, grains and thousand grain weight was on the basis of the sterile spikelet number and spikelet number; choosing the Ci, Fv/Fm and CCI was based on the Pn.