Non-flooded Mulching Cultivation Research Articles

Moderate wetting and drying increases rice yield and reduces water use, grain arsenic level, and methane emission

To meet the major challenge of increasing rice production to feed a growing population under increasing water scarcity, many water-saving regimes have been introduced in irrigated rice, such as an aerobic rice system, non-flooded mulching cultivation, and alternate wetting and drying (AWD). These regimes could substantially enhance water use efficiency (WUE) by reducing irrigation water. However, such enhancements greatly compromise grain yield. Recent work has shown that moderate AWD, in which photosynthesis is not severely inhibited and plants can rehydrate overnight during the soil drying period, or plants are rewatered at a soil water potential of −10 to −15kPa, or midday leaf potential is approximately −0.60 to −0.80MPa, or the water table is maintained at 10 to 15cm below the soil surface, could increase not only WUE but also grain yield. Increases in grain yield WUE under moderate AWD are due mainly to reduced redundant vegetative growth; improved canopy structure and root growth; elevated hormonal levels, in particular increases in abscisic acid levels during soil drying and cytokinin levels during rewatering; and enhanced carbon remobilization from vegetative tissues to grain. Moderate AWD could also improve rice quality, including reductions in grain arsenic accumulation, and reduce methane emissions from paddies. Adoption of moderate AWD with an appropriate nitrogen application rate may exert a synergistic effect on grain yield and result in higher WUE and nitrogen use efficiency. Further research is needed to understand root–soil interaction and evaluate the long-term effects of moderate AWD on sustainable agriculture.

Labile soil organic matter fractions as influenced by non-flooded mulching cultivation and cropping season in rice–wheat rotation

Labile soil organic matter (SOM) fractions are especially important because they are more vulnerable to disturbance and play a crucial role for nutrient and carbon cycling. Although water conservation has become increasingly important in rice–wheat rotation, the effects of non-flooded mulching cultivation on labile SOM fractions remain unknown. Based on a long-term field experiment (10 years), we analyzed the impact of non-flooded mulching cultivation and cropping season on labile SOM fractions in a rice–wheat rotation in Chengdu Plain, southwest China. Compared with traditional flooding (TF), the plastic film mulching (PM) and wheat straw mulching (SM) treatments increased dissolved organic carbon (DOC) (42% after rice season and 41% after wheat season), but decreased microbial biomass carbon (MBC) (19% after rice season and 28% after wheat season) and nitrogen (MBN) (17% after rice season and 24% after wheat season) in the 0–5 cm depth. SM increased particulate organic carbon (POC) and KMnO4-oxidizable C (KMnO4-C) contents after both the rice and wheat seasons. Microbial biomass and DOC concentrations were higher for all three cultivations after the rice season than after the wheat season. In contrast, POC contents under PM and SM were higher after the wheat season than after the rice season. In general, results in this study indicate that non-flooded mulching and cropping season significantly influenced labile SOM fractions. The DOC fraction was the most sensitive fraction affected by non-flooded mulching, while POC and PON fractions respond fast within the two cropping seasons.

Effect of Non-flooded Straw-mulching Cultivation on Grain Yield and Quality of Direct-seeding Rice

There are two problems in rice production in China: the one is the water shortage and another is labor shortage because of the climate change and economic development. Therefore, water-saving and labor-saving techniques should be developed. The direct-seeding is considered as a labor-saving while the non-flooded mulching cultivation as a water-saving practice. The aim of this study was to investigate if non-flooded straw mulching cultivation could maintain both grain yield and quality of direct-seeding rice. Two rice cultivars currently used in the production, Yangdao 6 (an indica) and Yangjing 4038 (a japonica), were field grown using a direct-seeding method, and three treatments, non-flooded wheat-straw-mulching (SM), non-flooded and no mulching (NM), and traditional flooding and no mulching (control, TF), were imposed from 10 days after sowing to maturity. Compared with that under TF, grain yield showed some reduction under both SM and NM. The reduction in yield was 1.9-6.6% under SM, and 18.0-27.6% under NM. The difference in grain yield was not significant between SM and TF, and was significant between NM and TF. SM significantly improved head rice, gel consistency, albumin, glutelin and eating quality, and significantly reduced chalky kernels, chalkiness and prolamine content, and NM had the opposite effect. The results indicated that non-flooded wheat-straw-mulching could maintain a high grain yield and improved grain quality for direct-seeding rice. Greater leaf photosynthetic rate, root activity, and contents of indole-3-acetic acid and zeatin+zeatin riboside under such a practice contributed to a high grain yield and better quality, whereas NM significantly reduced these physiological parameters, and consequently reduced grain yield and quality.

The relationship of grain filling with abscisic acid and ethylene under non-flooded mulching cultivation

SUMMARYGrain filling is an intensive transportation process regulated by plant hormones. The present study investigated whether and how the interaction between abscisic acid (ABA) and ethylene is involved in mediating the grain filling of rice (Oryza sativaL.) under non-flooded mulching cultivation. A field experiment repeated over 2 years was conducted with two high-yielding rice cultivars, Zhendao 88 (ajaponicacultivar) and Shanyou 63 (anindicahybrid cultivar), and four cultivation treatments were imposed from transplanting to maturity: traditional flooding as control (TF), non-flooded plastic film mulching (PM), non-flooded wheat straw mulching (SM) or non-flooded no mulching (NM). Compared with that under TF, grain yield was reduced by 21·0–23·1% under PM (P<0·05), 1·4–1·8% under SM (P>0·05) and 50·9–55·4% under NM (P<0·05). Both PM and NM significantly (P<0·05) reduced the proportion of filled grains and grain weight and were associated with decreased grain filling rates. In SM there was a significant increase in the grain filling rate. The concentration of ABA in the grains was very low at the early grain filling stage, reaching a maximum when the grain filling rate was the highest, and showed no significant differences (P>0·05) between TF, PM and SM. However, it was significantly higher in NM. In contrast to ABA, the ethylene evolution rate and 1-aminocyclopropane-1-carboxylic acid (ACC) concentration in the grains were very high at the start of grain filling and sharply decreased during the active grain filling period. Both PM and NM increased the ethylene evolution rate and ACC concentration, whereas these were reduced in SM. The ratio of ABA to ACC was increased under SM but decreased under PM and NM, indicating that ethylene was more enhanced than ABA when plants were grown under NM and PM. The concentration of ABA correlated with the grain filling rate as a hyperbolic curve, whereas the ethylene evolution rate correlated with the grain filling rate as an exponential decay equation. The ratio of ABA to ACC significantly correlated with the grain filling rate with a linear relationship. Application of amino-ethoxyvinylglycine (inhibitor of ethylene synthesis by inhibiting ACC synthase) or ABA to panicles under TF and PM at the early grain filling stage significantly increased activities of the key enzymes involved in sucrose to starch conversion in the grains, sucrose synthase, ADP glucose pyrophosphorylase and soluble starch synthase, grain filling rate and grain weight. Application of ethephon (ethylene-releasing agent) or fluridone (inhibitor of ABA synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene may be involved in mediating the effect of non-flooded mulching cultivation on grain filling, and a high ratio of ABA to ethylene enhances grain filling rate.

Yield, grain quality and water use efficiency of rice under non-flooded mulching cultivation

Plastic film or straw mulching cultivation under non-flooded condition has been considered as a new water-saving technique in rice production. This study aimed to investigate the yield performance in terms of quality and quantity and water use efficiency (WUE) under such practices. A field experiment across 3 years was conducted with two high-yielding rice cultivars, Zhendao 88 (a japonica cultivar) and Shanyou 63 (an indica hybrid cultivar) and four cultivation treatments imposed from transplanting to maturity: traditional flooding as control (TF), non-flooded plastic film mulching (PM), non-flooded wheat straw mulching (SM), and non-flooded no mulching (NM). Compared with those under the TF, root oxidation activity, photosynthetic rate, and activities of key enzymes in sucrose-to-starch conversion in grains during the grain filling period were significantly increased under the SM, whereas they were significantly reduced under the PM and NM treatments. Grain yield showed some reduction under all the non-flooded cultivations but differed largely among the treatments. The reduction in yield was 7.3–17.5% under the PM, 2.8–6.3% under the SM, and 39–49% under the NM. The difference in grain yield was not significant between TF and SM treatments. WUE for irrigation was increased by 314–367% under the PM, 307–321% under the SM, and 98–138% under the NM. Under the same treatment especially under non-flooded conditions, the indica hybrid cultivar showed a higher grain yield and higher WUE than the japonica cultivar. The SM significantly improved milling, appearance, and cooking qualities, whereas the PM or the NM decreased these qualities. We conclude that both PM and SM could significantly increase WUE, while the SM could also maintain a high grain yield and improve quality of rice. The SM would be a better practice than the PM in areas where water is scarce while temperature is favorable to rice growth, such as in Southeast China.

Crop Yields, Internal Nutrient Efficiency, and Changes in Soil Properties in Rice–Wheat Rotations Under Non-Flooded Mulching Cultivation

A field experiment was conducted for 5 years to examine the effects of non-flooded mulching cultivation on crop yield, internal nutrient efficiency and soil properties in rice–wheat (R–W) rotations of the Chengdu Plain, southwest China. Compared with traditional flooding (TF), non-flooded plastic film mulching (PM) resulted in 12 and 11% higher average rice (Oryza sativa L.) yield and system productivity (combined rice and wheat yields), and the trends in rice and wheat (Triticum aestivum L.) yields under PM were stable over time. However, non-flooded wheat straw mulching (SM) decreased average rice yield by 11% compared with TF, although no significant difference in system productivity was found between SM and TF. Uptakes of N and K by rice under PM were higher than those under TF and SM, but internal nutrient efficiency was significantly lower (N) or similar (K) under PM compared to SM and TF. This implies that more N and K accumulated in rice straw under PM. After 5-year rice–wheat rotation, apparent P balances (112–160 kg ha−1) were positive under all three cultivation systems. However, the K balances were negative under PM (−419 kg ha−1) and TF (−90 kg ha−1) compared with SM (45 kg ha−1). This suggests that higher K inputs from fertilizer, straw or manure may be necessary, especially under PM. After five rice seasons and four wheat seasons, non-flooded mulching cultivation led to similar (PM) or higher (SM) soil organic carbon (SOC), total N (TN) and alkali hydrolyzable N (AH-N) in the top 0–5 and 5–12 cm layers compared with TF. SOC, TN, AH-N and Olsen-P (OP) in the sub-surface layer (12–24 cm) were significantly higher under PM or SM than under TF, indicating that rice under non-flooded mulching conditions may fail to make use of nutrients from the subsoil. Thus, the risk of decline in soil fertility under non-flooded mulching cultivation could be very low if input levels match crop requirements. Our data indicate that PM and SM may be alternative options for farmers using R–W rotations for enhancement or maintenance of system productivity and soil fertility.

Crop production, nitrogen recovery and water use efficiency in rice–wheat rotation as affected by non-flooded mulching cultivation (NFMC)

Non-flooded mulching cultivation (NFMC) for lowland rice, as a novel water-saving technique, has been practiced in many areas of China since the 1990s. However, the information on NFMC effects on crop production, nitrogen and water use in rice–wheat rotations is still limited. A field experiment using 15N-labeled urea was conducted to evaluate the impacts of NFMC on crop yield, fertilizer N recovery and water use efficiency in rice–wheat rotations. Plastic film mulching (PM), and wheat straw and plastic film double mulching (SPM) resulted in the same rice grain yield (7.2 t ha−1) while wheat straw mulching (SM) and no mulching (NM) led to 5 and 10% yield reduction, compared with rice under traditional flooding (TF). In the rice–wheat rotation, crop productivity in PM, SM or SPM was comparable to that in TF but greater than in NM. Weed growth and its competition with rice for nitrogen were considered the main reason that led to yield decline in NM. Compared with TF, NFMC treatments did not obviously affect fertilizer N recoveries in plant and soil in both rice and wheat seasons. The total fertilizer N recoveries in crop, weed and soil in all treatments were only 39–44% in R–W rotations, suggesting that large N losses occurred following one basal N application for each growing season. Water use efficiency, however, was 56–75% greater in NFMC treatments than in TF treatment in the R–W rotation. The results revealed that NFMC (except NM) can produce comparable rice and wheat yields and obtain similar fertilizer N recovery as TF with much less water consumption.

Interactions between non-flooded mulching cultivation and varying nitrogen inputs in rice–wheat rotations

A 3-year field experiment examined the effects of non-flooded mulching cultivation and traditional flooding and four fertilizer N application rates (0, 75, 150 and 225 kg ha −1 for rice and 0, 60,120, and 180 kg N ha −1 for wheat) on grain yield, N uptake, residual soil N min and the net N balance in a rice–wheat rotation on Chengdu flood plain, southwest China. There were significant grain yield responses to N fertilizer. Nitrogen applications of >150 kg ha −1 for rice and >120 kg ha −1 for wheat gave no increase in crop yield but increased crop N uptake and N balance surplus in both water regimes. Average rice grain yield increased by 14% with plastic film mulching and decreased by 16% with wheat straw mulching at lower N inputs compared with traditional flooding. Rice grain yields under SM were comparable to those under PM and TF at higher N inputs. Plastic film mulching of preceding rice did not affect the yield of succeeding wheat but straw mulching had a residual effect on succeeding wheat. As a result, there was 17–18% higher wheat yield under N0 in SM than those in PM and TF. Combined rice and wheat grain yields under plastic mulching was similar to that of flooding and higher than that of straw mulching across N treatments. Soil mineral N (top 60 cm) after the rice harvest ranged from 50 to 65 kg ha −1 and was unaffected by non-flooded mulching cultivation and N rate. After the wheat harvest, soil N min ranged from 66 to 88 kg N ha −1 and increased with increasing fertilizer N rate. High N inputs led to a positive N balance (160–621 kg ha −1), but low N inputs resulted in a negative balance (−85 to −360 kg ha −1). Across N treatments, the net N balances of SM were highest among the three cultivations systems, resulting from additional applied wheat straw (79 kg ha −1) as mulching materials. There was not clear trend found in net N balance between PM and TF. Results from this study indicate non-flooded mulching cultivation may be utilized as an alternative option for saving water, using efficiently straw and maintaining or improving crop yield in rice–wheat rotation systems. There is the need to evaluate the long-term environmental risks of non-flooded mulching cultivation and improve system productivity (especially with straw mulching) by integrated resource management.

Effects of non-flooded mulching cultivation on crop yield, nutrient uptake and nutrient balance in rice–wheat cropping systems

A field experiment on a sandy loam was conducted to evaluate the effects of non-flooded mulching cultivation on the productivity, nutrient uptake and nutrient balance in rice–wheat (R–W) cropping systems in Chengdu flood plain, southwest China over a 3-year period. Plastic film mulching (PM) resulted in 12% higher average yield of rice while wheat straw mulching (SM) led to 14% lower average yield of rice compared with lowland rice under traditional flooding (TF). Biomass accumulation and nutrient uptake followed similar trends to grain yield. Changes in soil temperature in relation to root growth and nutrient uptake were likely to be the major factor responsible for the changes in rice yields under non-flooded mulching cultivation. Compared with TF, PM of preceding rice did not affect the grain yield of wheat, whereas SM of preceding rice resulted in comparable grain yields of wheat at a lower N rate (60 kg N ha −1) in the wheat season. The system productivity (total yield of rice+wheat) in PM was similar to that of TF and higher than that of SM. The yield decline in rice, however, could be partly compensated by the yield increase in wheat following rice, particularly at lower N rates. Apparent nutrient budgets showed positive nitrogen (N) and phosphorus (P) balances but negative potassium (K) balance in the TF and non-flooded mulching R–W systems. Compared with TF, PM led to lower NPK balance due to more nutrient removal by crops while SM led to greater NPK balance due to more nutrient inputs from straw but less nutrient removal by crops. After 3 years soil organic carbon (OC) and total nitrogen (TN) were not significantly altered by PM and SM but soil Olsen-P (AP) and exchangeable K (EK) were significantly increased by SM compared with TF. The changes in soil properties under non-flooded mulching cultivation initially reflected the nutrient balances in R–W systems. In conclusion, non-flooded mulching cultivation as PM and SM could be applied to R–W systems in southwest China but nutrient (especially N) management should be optimized in the two systems.