Search

To explore low–cost, high–yielding and environment–friendly rainfed farming technology is critical for sustainable agricultural development in semiarid east African Plateau (EAP). An innovative ridge–furrow mulching system (RFMS) was first introduced to EAP, with a two–year field experiment using maize cultivar KDVI in a typical semiarid site of Kenya from 2012 to 2013. Nine treatments were designed including ridge–furrow cultivation with black plastic mulching (RFB), straw mulching (RFS) and without mulching (RF) under high (375 kg ha−1), conventional (225 kg ha−1) and zero fertilization rates. We found RFB and RFS significantly increased soil water storage (0–40 cm) by 10.2% and 4.8%, while lowered evapotranspiration rate and improved thermal status, compared to RF across two growing seasons. Importantly, RFB and RFS increased soil organic carbon and C/N ratio (soil organic carbon/soil total nitrogen) by 7.8% and 4.9%, 7.2% and 5.1% respectively, following two growing seasons of farming practice. As expected, grain yield and water use efficiency (WUE) were averagely increased by 63.3% and 63.8%, 27.5% and 35.9% in RFB and RFS than those of RF respectively. Additionally, net income and economic output–to–input ratio were significantly greater in RFB and RFS than those of RF. On the other hand, conventional fertilization rate achieved similar grain yield and WUE as high fertilization did. Considering environmental and economic benefits, the RFMS farming system with conventional fertilization may act as a promising option to upgrade local dryland agricultural system in EAP.

Climate-related flowering phenology has attracted increasing concerns due to its irreplaceable contribution to innovative theory and application of plant phenology at global scale. Most of previous long-term observations were focused on interannual variations in flowering time in Europe and North America, however, very few of them in China were so far reported. Here, we present a meta-analysis through compiling the extended data set from 62 ground-based observations including 136 plant species from 217 observational sites across 8 climatic zones from 1963 to 2013 in China. Quantitative trends in 649 time series (1963–2013) of flowering phases and corresponding temperature changes were analyzed. The results indicated that the beginning, peak and ending of flowering were generally advanced by 2.2, 2.3 and 1.4 days decade−1, respectively, as a result of temperature increase. Flowering duration tended to be prolonged, mainly due to higher temperature sensitivity and greater advancement in the beginning of flowering rather than the ending of flowering. Particularly, the most pronounced advancement in flowering time was observed in east China, up to 3.6 days decade−1 as a result of contemporaneous warming. Specifically, flowering time of herbaceous plants displayed an advancing trend by 0.7 day decade−1 per degree of increasing latitude. Furthermore, early-flowering species tended to flower earlier than late-flowering ones did. Wind-pollinated and herb species showed greater phenological advancement and temperature sensitivity than insect-pollinated species and other growth forms did. Our results were to some extent different from those in Europe and North America, but played a critical and complementary role at global scale. Our findings and database presented should be powerful complements to address climate-associated flowering shifts and their ecological impacts at global scale.

The law of constant final yield and allometric theory have been seldom used to explore density-dependent yield formation and water use in rainfed farming systems, particularly in ridge-furrow mulching (RFM) system of maize. A two-year RFM field experiment was conducted using maize variety Yuyuan7879 in semiarid Kenya from 2015 to 2016, with four planting densities: 5.2 × 104 (D52, conventional density), 6.0 × 104 (D60), 6.9 × 104 (D69) and 8.5 × 104 (D85) plants per hectare. The grain yield and aboveground biomass per plant were significantly decreased with increasing density across two growing seasons. However, the population grain yield significantly was increased from D52 to D60 (from 3395.1–4471.7 kg ha−1) but declined significantly from D60 to D69 and D85 (p

Allometry is extensively used to describe the scaling relationship between individual size and metabolite allocation. Micro-field rain-harvesting system can improve soil water availability and thus alter the allocation of individual biomass among organs. Yet the eco-physiological mechanism based on allometric scaling theory has been little investigated under various mulching conditions. A field experiment was conducted using maize variety Yuyuan7879 in Juja, Kenya for two growing seasons (cross-year) from 2015 to 2016, and from 2016 to 2017 respectively. Four treatments were designed as ridge-furrow mulching (RFM) with black plastic mulching (RFMB), transparent plastic mulching (RFMT), grass straw mulching (RFMG) and conventional flat planting (CK). We found that RFMB, RFMT and RFMG significantly increased grain yield by 106%, 109% and 32% in 2015, and 101%, 96% and 30% in 2016 respectively, in comparison with CK. Mulching treatments improved soil temperature and moisture and significantly increased crop water productivity (CWP). Mulching treatments drastically changed the allometric relationship between metabolic rate (leaf biomass) and individual size (lgy = αlgx + lgβ), and optimized the size-dependent reproductive allocation. In the relationship between leaf biomass (y-axis) vs aboveground biomass (x-axis), mulching treatments significantly declined the value of α (α

Micro-field rain-harvesting farming system (MRFS) has demonstrated great potentials to enhance field productivity and profitability of dryland wheat (Triticum aestivum L.) in semiarid eastern Asia, yet little is known whether this system results in desired effects in semiarid Africa such as Kenya. A two-year field experiment was conducted during 2012 and 2013 growing seasons to evaluate the effects of introduced MRFS on water availability, field productivity and economic benefits using a local wheat (T. aestivum L.) cultivar DUMA in a semiarid site of Kenya. Five treatments were designed as: 1) ridge and furrow with transparent plastic mulching (RFT); 2) ridge and furrow with black plastic mulching (RFB); 3) ridge and furrow with grass straw mulching (RFS); 4) ridge and furrow without mulching (RF); and 5) traditional flat planting (CK). The results showed that mulching treatments (RFT, RFB and RFS) significantly decreased the evapotranspiration (ET) by 11.4–88.5 mm, increased wheat grain yield by 60%–163%, above-ground biomass by 58%–104% and water use efficiency for grain by 68%–271%, compared with CK over two growing seasons. RFT and RFB treatments resulted in maximal soil water storage at 1-m depth and the greatest harvest index among all treatments. Linkage analyses indicated that grain yield showed significantly positive correlation with plant height, leaf area and major spike components (P ≤ 0.05), suggesting that plant type of wheat was altered for better yield production as a result of MRFS operation. More importantly, economic ratios of output to input were also calculated and compared. The average ratio of output to input for CK was 3.86, slightly lower than 4.28, 4.06, 5.86 and 5.34 for RFT, RFB, RFS and RF, respectively across two growing seasons. In particular, net incomes in MRFS (RFT, RFB, RFS and RF) were increased by 145%, 128%, 117% and 82% respectively, compared with that of CK. In conclusion, on-field rain-harvesting farming system provides an innovative management to boost the productivity and profitability of dryland wheat, and a potential solution to cope with food security in semiarid Kenya.

The extreme climate events such as El Nino seriously threaten crop production and agro-ecological sustainability because of the aggravated environmental stresses worldwide, particularly in sub-Saharan Africa. To address this issue, we investigated the effects of dual plastic film and straw mulching in ridge-furrow (RF) system on wheat productivity, soil carbon and nitrogen stocks in a semiarid area in Kenya from 2015 to 2017. The experimental site represents a typical semiarid continental monsoon climate, and soil type is chromic vertisols. Field experiment with randomized block design consisted of six RF treatments as follows: 1) dual black plastic film and straw mulching (RFbS), 2) dual transparent plastic film and straw mulching (RFtS), 3) sole black plastic film mulching (RFb), 4) sole transparent plastic mulching RF (RFt), 5) sole straw mulching (RFS) and 6) no mulching (CK). The results indicated that seasonal dynamics of rainfall and air temperature fit in with the weather type of El Nino over four growing seasons. RFbS, RFtS, RFb and RFt significantly increased soil water storage (SWS), topsoil temperature, aboveground biomass, grain yield and water use efficiency across four growing seasons (p 0.05) as compared with CK. Among all the treatments, RFbS and RFtS achieved the greatest SWS, AgB, grain yield and WUE, owing to improved soil hydro-thermal status in both treatments. Critically, RFbS and RFtS significantly improved soil organic carbon and total nitrogen, soil bulk density and the C:N ratio following four growing seasons, comparing with other treatments (p 0.05). Besides, RFbS and RFtS gave the highest economic returns among all treatments. For the first time, we found that dual plastic film and straw mulching could serve as a sustainable land management to boost wheat productivity and improve soil quality under El Nino in semiarid areas of SSA.

Conventional polyethylene plastic film mulching has been widely used, but its subsequent plastic residue pollution received widespread concern. Fully biodegradable film mulching is viewed as a potential substitution solution, however, it is generally thought not to be efficient as conventional plastic film mulching in field productivity and economic harvest. A two-year field experiment using a newly produced fully biodegradable film was conducted in semiarid Kenya in 2016 and 2017 respectively. Five treatments were designed as: 1) ridge-furrow mulching (RFM) with transparent plastic film (RFMT), 2) RFM with fully biodegradable film (RFMD), 3) RFM with black plastic film (RFMB), 4) RFM with grass straw (RFMG) and 5) traditional flat planting without mulching (FP) as CK. We found that RFMD achieved the similar evaporation-restricted, yield-increased and water-saving effectiveness as RFMT and RFMB did across two growing seasons. The RFMD lowered evaporation by 58.1 mm, while increasing grain yield by 70.16 %, above-ground biomass by 77.7 % and water use efficiency (in reference to grain yield) (WUEG) by 131.8 % in comparison with CK respectively. Furthermore, RFMD increased net economic income by 49.8 % in 2016 and 42.0 % in 2017 respectively relative to CK, as RFMT and RFMB did. It is noted that the degradable film used in this experiment is a non-polyethylene material and still can be maintained for 60 days in a fine physical state. Also, average soil temperature was significantly elevated by 1.6 °C in 2016 and 1.8 °C in 2017 in RFMD respectively, in comparison with CK, which was beneficial to crop growth and grain filling particularly in relatively cool long rainy season. Considering residual film pollution, the biodegradable film showed reliable advantages in environmental friendliness and field productivity. Therefore, it might be a promising farming solution to boost rainfed maize production and environmental sustainability in east African Plateau.

Inoculation with arbuscular mycorrhizal (AM) fungi can modify stomatal behavior and increase antioxidant enzyme activities and therefore play a pivotal role in plant growth. We hypothesised that inoculation with AM fungi postpones the non-hydraulic root signal and alters physiological and biochemical traits, which enhances drought tolerance and water-use efficiency (WUEB) for plant biomass. Two pot experiments (including progressive soil drying and partial root-zone drying) were conducted to reveal how mycorrhizal colonization altered root signal and its effects on plant growth, biochemical traits and WUEB in maize seedlings in drying soil. In our experiments, inoculation with Funneliformis mosseae improved water absorption and reduced the sensitivity of roots to drought. In addition, it decreased leaf abscisic acid (ABA) content of inoculated plants. Regardless of water conditions, plant biomass production, antioxidant enzyme activity, net photosynthetic rate, stomatal conductance and WUEB were elevated in AM fungal treatments compared to non-AM fungal treatments. Under water-stressed conditions, inoculation with F. mosseae greatly reduced leaf ABA content, and postponed the decline in photosynthetic rate, stomatal conductance and osmotic adjustment. Malondialdehyde (MDA) level was significantly lower in mycorrhizal plants than in non-inoculation plants. However, inoculation with F. mosseae increased antioxidant enzyme activities including peroxidase (POD) and superoxide dismutase (SOD). In this study, inoculation with F. mosseae reduced ABA accumulation that acts as a non-hydraulic root signal and thereby postponed a decline in stomatal conductance and photosynthetic rate, improved water use efficiency and antioxidant enzymes activities, and accordingly reduced proline and MDA content. Thus, inoculation with AM fungi played a role in effective defense for better drought acclimation in water-stressed maize seedlings.