Effects of planting density on photosynthetic characteristics of flag leaf and senescence of leaf and root under wide-width sowing condition.

To determine the optimal planting density under wide-width sowing condition, we investigated the effects of different planting densities on photosynthetic characteristics of flag leaves, senescence characteristics of flag lea-ves and roots, grain yield, and water use efficiency under four planting density levels, 90×104 plants·hm-2 (D1), 180×104 plants·hm-2 (D2), 270×104 plants·hm-2 (D3) and 360×104 plants·hm-2 (D4), in field condition set in Yanzhou, Shandong during the growing season of 2018-2019 and 2019-2020. The results showed that compared with D1 and D4 treatments, D2 treatment significantly improved photosynthetic characteristics of wheat flag leaves during grain filling, increased the activity of superoxide dismutase (SOD) and soluble protein content, reduced the malondialdehyde (MDA) content, and delayed the senescence of flag leaves and roots. Compared with other treatments, D2 treatment significantly increased root length, root surface area and root volume in 0-40 cm soil layer. Compared with D1, D3 and D4 treatments, the grain yield of D2 treatment was increased by 11.8%, 2.5%, 6.4% in 2018-2019 and 22.7%, 5.7%, 17.1% in 2019-2020, respectively. In addition, water use efficiency was increased by 9.2%, 8.8%, 14.2% in 2018-2019 and 21.1%, 6.2%, 21.5% in 2019-2020, respectively. The planting density at 180×104 plants·hm-2 improved photosynthetic characteristics of flag leaves and root morphology during filling stage, delayed plant senescence, increased grain number per spike and grain weight. Consequently, the highest grain yield and water use efficiency were obtained under D2 treatment, which was the optimal treatment under the experimental wide-width sowing condition.

[Effects of water-fertilizer integration on water use and photosynthetic characteristics of winter wheat]. / æ°´è‚¥ä¸€ä½“åŒ–å¯¹å°éº¦æ°´åˆ†åˆ©ç”¨å’Œå ‰åˆç‰¹æ€§çš„å½±å“.

In two growing seasons of wheat (2016-2018), a field trial with Jimai 22 as test mate-rial was conducted in Shijiawangzi Village, Yanzhou City, Shandong Province. Under three nitrogen levels of 150 (N1), 180 (N2) and 210 (N3) kg·hm-2, two irrigation-fertilization methods were designed at jointing as border irrigation and broadcasting of fertilizer (W1), micro spraying irrigation and water-fertilizer integration (W2), to examine the effects of irrigation-fertilization methods on water use, photosynthetic characteristics, and dry matter accumulation and transport of wheat. The results showed that under the same nitrogen level, seven days average soil evaporation of W2 treatment in filling period was significantly lower than that of W1 treatment, and that soil water consumption in the 60-160 cm soil layer was significantly higher than that in W1 treatment. The flag leaf net photosynthetic rate, stomatal conductance and transpiration rate of W2 treatment were signi-ficantly higher than W1 treatment from 14 to 28 days after anthesis. The amount of dry matter in anthesis and maturity stage and the allocation to grain of post-anthesis assimilates of W2 treatment were significantly higher than those in W1 treatment. There was no difference in total water consumption between W2 and W1 treatments. Grain yield, water use efficiency and nitrogen use efficiency of W2 treatment were significantly higher than W1 treatment. The highest grain yield, water use efficiency and nitrogen use efficiency were obtained at the nitrogen level of 210 kg·hm-2. By comprehensive considerations, under the same nitrogen level, treatment of micro spraying irrigation and water-fertilizer integration was better than border irrigation and broadcasting of fertilizer. The W2N3 treatment under the nitrogen level of 210 kg·hm-2 and with the application of micro spraying irrigation and water-fertilizer integration at jointing was the optimal treatment to save water and fertilizer.

[Effects of micro-sprinkling hose irrigation with different hose lengths on soil water distribution, dry matter accumulation, and grain yield of wheat fields]. / 不同带长微喷带灌溉对麦田土壤水分分布和干物质积累及籽粒产量的影响.

To explore the optimal hose length of micro-sprinkling hose irrigation in wheat fields, a field trial taking JiMai 22 as test material was carried out in two growing seasons (2015-2016 and 2016-2017). Three lengths of micro-sprinkling hoses with 80-mm width were used, including 60 m (T1), 80 m (T2) and 100 m (T3). The length of trial plot was equal to the hose length. The trial plots were divided to different sample sections every 20-m length along the irrigation direction, which were named as A, B, C, D and E sections, respectively, to examine the effects of micro-sprinkling hose irrigations with different hose lengths on soil water distribution, dry matter accumulation and grain yield of wheat fields. The results showed that: 1) After irrigation at the jointing and anthesis stages in the two growing seasons, the relative soil water content in the 0-40 cm soil layer showed T1T2, T3 in the C section and T2>T3 in the D section. The CV of relative soil water content in different sections in the same treatment showed T1T2, T3 in the C section and T2>T3 in the D section. Leaf area index and rate of canopy photosynthesis active radiation interception at 20 d and 30 d after anthesis and dry matter accumulation amount after anthesis showed T1, T2>T3, and dry matter accumulation amount at the maturity stage showed T1> T2>T3. 3) In the two growing seasons, grain yield in the A and B sections had no significant differences among different treatments, and that showed T1>T2, T3 in the C section and T2>T3 in the D section. Grain yield of each treatment showed T1, T2>T3. 4) The grain yield and water use efficiency showed T1> T2>T3, and the irrigation water use efficiency showed T1>T2>T3 among different treatments in the two growing seasons. Considering grain yield and water use efficiency, hose irrigation with micro-sprinkling hose at 80-mm width and 60-m length was optimal treatment for water-saving and high-yield irrigation, and the suboptimal length was 80 m under this condition. The results could provide theoretical basis for water-saving and high-yield irrigation with micro-sprinkling hose in wheat fields in Shandong Province.

[Effects of micro-sprinkling hose length and width on wheat field water condition and flag leaf chlorophyll fluorescence characteristics in different sampling districts]. / å¾®å–·å¸¦é•¿å®½å¯¹ä¸åŒåŒºæ®µéº¦ç”°æ°´åˆ†å’Œå°éº¦æ——å¶å¶ç»¿ç´ è§å ‰ç‰¹æ€§çš„å½±å“.

A two-year field experiment was conducted in 2014-2015 and 2015-2016 wheat growing seasons to study the effects of micro-sprinkling hose length and width on field water condition, and flag leaf chlorophyll fluorescence characteristics in different sampling districts (D1 to D6 along with the hose laying direction). Six micro-sprinkling hose treatments were set: 60 m (T1), 80 m (T2) and 100 m (T3) lengths under 65 mm width; 60 m (T4), 80 m (T5) and 100 m (T6) lengths under 80 mm width. The results showed that after irrigation at jointing, the Christiansen uniformity coefficient (Cu) of T1 was significantly higher than T2 and T3 under 65 mm hose width. Under 80 mm hose width, T4 and T5 had the highest Cu compared to T6. After irrigation at anthesis, the Cu showed T1>T2>T3 under 65 mm hose width, and T4>T5>T6 under 80 mm hose width. Under 65 mm hose width, the average relative soil water content of 0-40 cm soil layers after irrigation at anthesis, flag leaf ΦPSII, NPQ and ETR at 20 and 30 d after anthesis and the grain yield of different sampling district did not differ in T1; T2 showed the order of D1, D2>D3>D4>D5; T3 showed D1, D2>D3>D4>D5, D6. The average ΦPSII, NPQ and ETR at 20 and 30 d after anthesis, and the average dry matter at maturity of different sampling districts were presented as T1>T2, T3. Under 85 mm hose width, no significant differences were observed in the average relative soil water content of 0-40 cm soil layers after irrigation at ahthesis, flag leaf ΦPSII, NPQ and ETR at 20 and 30 d after anthesis and the grain yield of different sampling districts in T4; in T5, the indexes mentioned above in D1, D2 and D3 sampling districts were significantly higher than those in D4 and D5; in T6, the decreasing order was D1, D2, D3>D4>D5>T6. The average ΦPSII, NPQ and ETR at 20 and 30 d after anthesis, and the average dry matter at maturity of different districts showed the order of T4, T5>T6. The ave-rage grain yield and water use efficiency of T1, T4 and T5 were significantly higher than those in T2, T3 and T6, T1 and T4 had a better irrigation benefit than T5. Under this experimental condition, T1 treatment under 65 mm hose width, T4 treatment under 80 mm hose width were the most recommendable treatments considering high yield and water saving, and T5 treatment was also recommendable under 80 mm hose width.

[Effects of supplemental irrigation by measuring soil moisture on water consumption chara-cteristics and radiation utilization in wheat]. / è¶Šå†¬æœŸæµ‹å¢’è¡¥çŒå¯¹å°éº¦è€—æ°´ç‰¹æ€§å’Œå ‰åˆæœ‰æ•ˆè¾å°„æˆªèŽ·åˆ©ç”¨çš„å½±å“.

Field experiments were conducted during 2013-2014 and 2014-2015 winter wheat growing seasons by using Jimai 22 as test material. Five treatments were designed: W0(non-irrigation during growth season), W1(non-irrigation at overwintering, but irrigated to 65% of field capacity (FC) at jointing and 70% of FC at anthesis in 0-40 cm soil layer), W2(irrigated to 70% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively) and W3(irrigated to 75% of FC at overwintering, 65% of FC at jointing and 70% of FC at anthesis in 0-40cm soil layer, respectively), W4(irrigated 60 mm at overwintering, jointing and anthesis stages, respectively). The aim was to clarify the effects of supplemental irrigation on water consumption characteristics and photosynthetically active radiation utilization in wheat. Results showed that the total irrigation amount and its ratio to total water consumption in each treatment were ranked as W4＞W3＞W2＞W1＞W0. However, the percentage of water consumption in soil to total water consumption was presented as W0＞W1, W2＞W3, W4. The total water consumption, water consumption from anthesis to maturity were ranked as W4＞W2, W3＞W1＞W0. The order of photosynthetically active radiation (PAR) capture ratio was W4＞W2, W3＞W1＞W0, but the order was contrary in PAR reflect ratio among the treatments. The net accumulation of dry matter was ranked as W4＞W2＞W3＞W1＞W0 in the two growing seasons. During the two winter wheat growing seasons, the grain yield in W2 was higher than in the other treatments, except W4, but the irrigation efficiency and water use efficiency in W2 were the highest. Concerning both the high-yield and high-water use efficiency in this experiment, the most appropriate irrigation regime was W2 treatment.

[Effects of long term tillage practices on photosynthetic characteristics and grain yield of wheat]. / é•¿æœŸè€•ä½œæ–¹å¼å¯¹å°éº¦å ‰åˆç‰¹æ€§å’Œäº§é‡çš„å½±å“.

A field experiment was conducted to study the effects of long-term tillage practices on photosynthetic characteristics of flag leaf, dry matter accumulation and its allocation, and grain yield, with a wheat cultivar, Jimai 22, in both 2013-2014 and 2014-2015 growing seasons. Four tillage practices, namely rotary tillage (R), plowing (P), strip rotary tillage and subsoiling at an interval of 2 years (SRS), and rotary tillage and subsoiling at an interval of 2 years (RS), were conducted in field for 9 years since 2007. The results showed that the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (gs) of flag leaves under SRS treatment were significantly higher than those of other treatments from 21 to 35 days after anthesis. The SRS treatment had higher average photosynthetically active radiation (PAR) capture ratio than RS and P treatments, while the lowest values were found under R treatment during grain-filling stage. Compared with the other treatments, the plants of SRS treatment had the highest accumulation of dry matter at maturity, the highest allocation of dry matter in grains, and the highest contribution ratio of dry matter from vegetative organs to grains after anthesis. The grain yield and water use efficiency of SRS treatment were significantly higher than those of the other treatments, and the water consumption amount of SRS treatment was significantly higher than that of both R and P treatments, with no significant difference from the RS treatment. Under the current experimental condition, it was suggested that SRS would be the most effective tillage practice to increase both grain yield and water use efficiency for winter wheat production.

[Effects of supplemental irrigation based on soil moisture on photosynthetic characteristics and enzyme activity of flan leaf in wheat].

A field experiment was conducted to study the effects of supplemental irrigation based on soil moisture on the photosynthesis characteristics and enzyme activity of flag leaf using the wheat cultivar Jimai 20. Three irrigation treatments were designed with target soil moisture of 65% (W65), 70% (W70) and 75% (W75) both at jointing and anthesis stages. Zero-irrigation ( CK) was used as the control. The results showed that the net photosynthetic rate (Pn) of flag leaf in treatment W70 was dramatically higher than in other treatments from 14 to 21 days after anthesis, as well as sucrose content and sucrose phosphate synthase (SPS) activity. The dry matter mass per area of W70 was higher than that of W65 and CK, and was not significantly different from that of W75. The single stem mass of W70 was higher than that of the other treatments. The activities of superoxide dismutase (SOD) and catalase (CAT) and the soluble protein concentration in flag leaf of W70 were significantly higher than in other treatments from 14 to 28 days after anthesis. The malondialdehyde (MDA) content of W70 was lower than that of W65 and CK, and was not significantly different from that of W75 from 14 to 21 days after anthesis. Grain yields of W70 were 8941.4 and 9125.4 kg · hm⁻² in the 2012-2013 and 2013-2014 wheat growing seasons, showing no significant difference with those of W75, but obviously higher than those of W65 and CK. And the water use efficiency (WUE) of W70 was the highest. Considering grain yield and WUE, maintaining the relative soil water content at 70% by supplemental irrigation both at jointing and anthesis stages was the best treatment.

[Effects of field border length for irrigation on photosynthetic characteristics, dry matter accumulation and water use efficiency of wheat].

With the high-yielding winter wheat cultivar Jimai 22 as test material, a three-year field experiment was conducted to examine the effects of border length for irrigation on flag leaf water potential, photosynthetic characteristics, dry matter accumulation and distribution of wheat. In the 2010-2011 growing season, six treatments were installed, i. e., the field border length was designed as 10 m (L10), 20 m (L20), 40 m (L40), 60 m (L60), 80 m (L80) and 100 m (L100). In the 2011-2012 and 2012-2013 growing seasons, the field border length was designed as 40 m (L40), 60 m (L60), 80 m (L80) and 100 m (L100). The results showed that the average relative soil water content of the 0-200 cm soil layer was presented as L80, L60>L100>L40>L20>L10 at anthesis in the 2010-2011 growing season and as L80, L60>L100>L40 in the 2011-2012 and 2012-2013 growing seasons. At 11 d and 21 d after anthesis, the water potential, net photosynthetic rate and transpiration rate of flag leaf were presented as L80, L100>L60>L40>L20, L10, and as L80>L60, L100>L40, L20, L10 at 31 d after anthesis. The coefficients of variability both of the dry matter accumulation at anthesis and maturity and of grain yield in different regions of L80 field were lower than those of L100. The average dry matter accumulation, dry matter accumulation after anthesis and the contribution to grain of L80 were dramatically higher than those of L100, L40, L20 and L10. L80 had the highest average grain yield and water use efficiency, being the best treatment for irrigation in our study.

[Effects of supplemental irrigation based on the measurement of moisture content in different soil layers on the water consumption characteristics and grain yield of winter wheat].

In 2010-2011, a field experiment with high-yielding winter wheat cultivar Jimai 22 was conducted to study the effects of supplemental irrigation based on the measurement of moisture content in different soil layers on the water consumption characteristics and grain yield of winter wheat. Four soil layers (0-20 cm, W1; 0-40 cm, W2; 0-60 cm, W3; and 0-140 cm, W4) were designed to make the supplemental irrigation at wintering stage (target soil relative moisture content = 75%), jointing stage (target soil relative moisture content = 70%), and anthesis stage (target soil relative moisture content = 70%), taking no irrigation (W0) during the whole growth season as the control. At the wintering, jointing, and anthesis stages, the required irrigation amount followed the order of W3 > W2 > W1. Treatment W4 required smaller irrigation amount at wintering and jointing stages, but significantly higher one at anthesis stage than the other treatments. The proportion of the irrigation amount relative to the total water consumption over the entire growth season followed the sequence of W4, W3 > W2 > W1. By contrast, the proportion of soil water consumption relative to the total water consumption followed the trend of W1 > W2 > W3 > W4. With the increase of the test soil depths, the soil water utilization ratio decreased. The water consumption in 80-140 cm and 160-200 cm soil layers was significantly higher in W2 than in W3 and W4. The required total irrigation amount was in the order of W3 > W4 > W2 > W1, the grain yield was in the order of W2, W3, W4 > W1 > W0, and the water use efficiency followed the order of W2, W4 > W0, W1 > W3. To consider the irrigation amount, grain yield, and water use efficiency comprehensively, treatment W2 under our experimental condition could be the optimal treatment, i. e., the required amount of supplemental irrigation based on the measurement of the moisture content in 0-40 cm soil layer should be feasible for the local winter wheat production.