[Effects of maize and peanut co-ridge intercropping on crop photosynthetic characteristics and intercropping advantages]. / çŽ‰ç±³å’ŒèŠ±ç”ŸåŒåž„é—´ä½œå¯¹ä½œç‰©å ‰åˆç‰¹æ€§å’Œé—´ä½œä¼˜åŠ¿çš„å½±å“.

To clarify the photosynthetic mechanism contributing to the enhancement of intercropping advantages through co-ridge intercropping of maize and peanut, we conducted a field randomized block experiment under two phosphorus levels of 0(P0) and 180 kg P2O5·hm-2(P180) with flat intercropping of maize and peanut (FIC) as the control. We analyzed the effects of co-ridge intercropping of maize and peanut (RIC) and groove-ridge intercropping of maize and peanut (GIC) on crop leaf area index (LAI), SPAD values, CO2 carboxylation ability, photosystems coordination (ΦPSⅠ/PSⅡ), and intercropping advantage of yield. The results showed that RIC significantly increased SPAD value at the silking stage of intercropping maize, and significantly improved the apparent quantum yield of photosynthesis (AQY), maximum electron transfer rate (Jmax), maximum rate of Rubisco carboxylation (Vc,max), net photosynthetic rate at the CO2 saturation (Amax) and ΦPSⅠ/PSⅡ of intercropping maize compared with those of FIC and GIC at silking stage and milking stage, but reduced the ratio of variable fluorescence Fk to amplitude Fj-Fo(Wk) and the ratio of variable fluorescence Fj to amplitude Fp-Fo(Vj) of the functional leaf photosystem Ⅱ (PSⅡ) at the milking stage of maize. There were no significant differences in these parameters between FIC and GIC. Compared with FIC, both RIC and GIC increased LAI of intercropping peanut at late growth stage and SPAD value at pod setting stage, significantly improved Vc,max, Amax, and ΦPSⅠ/PSⅡ, and reduced Wk and Vj values of intercropping peanut functional leaves at pod expanding stage. The difference in these parameters between RIC and GIC were not significant. The land equivalent ratio and intercropping advantages of RIC were higher than those of FIC and GIC. Phosphorus application could further promote Vc,max, Jmax, Amax and ΦPSⅠ/PSⅡ of intercropping maize and peanut, and significantly improve yield advantages of intercropping. The findings indicated that co-ridge intercropping could enhance CO2 carboxylation and fixation by improving photosynthetic electron transport and pho-tosystems coordination, improve the photosynthetic rate of functional leaves of maize and peanut, thus increase crop yield and intercropping advantages.

[The effects of sesame/peanut intercropping on photosynthetic fluorescence characteristics in functional leaf of sesame.] / èŠéº»ä¸ŽèŠ±ç”Ÿé—´ä½œå¯¹èŠéº»åŠŸèƒ½å¶å ‰åˆè§å ‰ç‰¹æ€§çš„å½±å“.

To unravel functional leaf photosynthetic mechanisms underlying enhanced yield of sesame in sesame/peanut intercropping, a field experiment was carried out in 2017 and 2018 with four treatments including (1) three-row sesame intercropped with six-row peanut (IC 3:6), (2) two-row sesame intercropped with four-row peanut (IC 2:4), (3) sole cropped sesame (SS), and (4) sole cropped peanut (SP). We measured the parameters of gas exchange, characteristics of photosynthetic response curve to light and CO2, and characteristics of chlorophyll rapid fluorescence induction kinetic curves of the functional leaves of sesame. The results showed that the partial land equivalent ratio of intercropped sesame was greater than 1/3. The light saturation point (Isat), maxi-mum net photosynthetic rate (Pn max), maximum electron transport rate (Jmax), triose phosphate utilization rate (TPU), maximum carboxylation rate of Rubisco (Vc max) were increased significantly under intercropping. Further, absorption energy flux per CS (ABS/CSo), trapping energy flux per CS (TRo/CSo), number of active reaction centers per CS (RC/CSm), and electron transport flux per CS (ETo/CSo) in intercropped treatments were enhanced compared to that under sesame monoculture. However, the ratio between variable fluorescence Fk to amplitude Fj-Fo (Wk) and ratio between variable fluorescence Fj to amplitude Fp-Fo (Vj) in functional leaves of intercropped sesame were significantly decreased. The efficiency of converting light energy into electricity of PS2 reaction center (Ψo), electron transfer efficiency from PS2 to end acceptor of PS1 (ΨRo), electron transfer efficiency of the electron transport chain (δR), PS1 photochemical activity, and the coordination between PS2 and PS1 in functional leaves of intercropped sesame were increased. The net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), Pn max, Jmax, Vc max, TPU, Ψo, ΨRo and δR were significantly higher in IC 3:6 than those in IC 2:4. We conclude that intercropping improves net photosynthetic rate and yield of sesame by increasing light absorption, electronic transmission, activity of PS2 donator/receptor sides, and CO2 fixation, with stronger effects in IC 3:6 than IC 2:4.

Root and nitrate-N distribution and optimization of N input in winter wheat.

Scientific management of nitrogen (N) fertilizer has a significant effect on yield while also reducing the environmental risks. In this study, we conducted field experiments over three years at two different sites (Zhengzhou and Shangshui) in Henan Province, China, using different N application rates (0, 90,180, 270, and 360 kg ha-1) to determine the relationships between soil N supply and N demand in winter wheat (Triticum aestivum L.). Optimal N input was then determined. Both sites showed the same trend. Namely, aboveground N uptake and soil nitrate N (NO3--N) increased with increasing N, while NO3--N decreased with increasing soil depth, gradually moving downwards with growth. A significant correlation (p < 0.001) between increasing aboveground N uptake and increasing NO3--N was also observed under N application, with the best relationships occurring in the 20-60 cm layer during jointing-anthesis (R2 = 0.402-0.431) and the 20-80 cm layer at maturity (R2 = 0.474). Root weight density showed the same spatial-temporal characteristics as NO3--N, following a unimodal trend with increasing N, and peaking at 90 kg ha-1. The root weight density was mainly distributed in the 0-60 cm layer (above 80%), with the 20-60 cm layer accounting for 30% of the total root system. In this layer, the root weight density was also significantly positively correlated with aboveground N uptake. Wheat yield reached saturation under high N (>270 kg ha-1), with a sharp decrease in N use efficiency (NUE) and linear increase in residual NO3--N. To balance yield and the risk of environmental pollution in the experimental area, an N application rate of 180-270 kg ha-1 is recommended under sufficient irrigation, thereby supporting a well-developed root system while ensuring balance between N supply and demand.

[Effects of maize/peanut intercropping row ratio and phosphate fertilizer on photosynthetic characteristics of maize.] / 玉米/èŠ±ç”Ÿé—´ä½œè¡Œæ¯”å’Œæ–½ç£·å¯¹çŽ‰ç±³å ‰åˆç‰¹æ€§çš„å½±å“.

To get better insight into the photosynthetic mechanism of plant adaptation to strong light in intercropped maize, a field trial was carried out in 2014-2015 to investigate the effects of maize/peanut intercropping row ratio and phosphate fertilizer on diurnal variation in light intensity of maize canopy, SPAD value, and the curves of photosynthetic response of net photosynthetic rate (Pn) to photon flux density (PFD) and to CO2 of functional leaves. The field trial comprised 2 rows maize intercropped with 2 rows peanut (2:2, R1), 2 rows maize intercropped with 4 rows peanut (2:4, R2) and 2 rows maize intercropped with 8 rows peanut (2:8, R3). Results showed that the light intensity of intercropped maize canopy was R3>R2>R1. From pre-tasselling to filling stage, the SPAD value, apparent quantum efficiency (AQY), light compensation point (LCP), light saturation point (LSP), maximum net photosynthetic rate, carboxylation efficiency (CE), maximum electron transfer rate (Jmax), triose phosphate utilization (TPU), stomatal conductance (gs), transpiration rate (Tr) and Pn in ear leaves of intercropped maize were R3>R2>R1, but the intercellular CO2 concentration (Ci) was R1>R2>R3. At dough stage, the AQY, LSPn, gs, CE, Jmax and TPU in ear lea-ves of intercropped maize in R3 intercropping system were lower than those in R2 intercropping system. The photosynthetic indices, such as AQY, LSPn, CE, Vc max, Jmax and TPU were increased by phosphate fertilizer application. These results suggested that the key mechanisms that enhanced strong light utilization ability of intercropped maize were attributed to gradual improvement in gs, AQY, CE, Vc max, Jmax and TPU of ear leaves with increasing light intensity, however, beyond a certain light intensity, intercropped maize leaves were prone to premature senescence. Nonetheless, phosphate fertilizer could improve light utilization and delay leaf senescence in intercropped maize.

[Effects of maize-peanut intercropping on economic yield and light response of photosynthesis].

A field experiment was conducted to study the effects of maize-peanut intercropping on the economic yield of the two crops and the light response of their functional leaves' photosynthesis. The results showed that maize-peanut intercropping had an obvious yield advantage, with the total economic yield being 2,896 kg hm(-2) in 2004 and 2,894 kg hm(-2) in 2005, and enhanced the land utilization rate by 14%-17%. For maize's functional leaves, the intercropping enhanced their light saturation point, compensation point, and photosynthetic rate under strong light; while for peanut's functional leaves, it reduced their light saturation point and compensation point but enhanced the apparent quantum yield of photosynthesis and photosynthetic rate under weak light, indicating that maize-peanut intercropping enhanced the utilization efficiency of strong light by maize and that of weak light by peanut, making this intercropping system present an obvious yield advantage.