Diethyl Aminoethyl Hexanoate Increase Relay Strip Intercropping Soybean Grain by Optimizing Photosynthesis Aera and Delaying Leaf Senescence

Insufficient and unbalanced biomass supply inhibited soybean [Glycine max (L.) Merr.] yield formation in the maize-soybean relay strip intercropping (IS) and monoculture soybean (SS). A field experiment was conducted to explore the soybean yield increase mechanism of DA-6 in IS and SS treatments. In this 2-year experiment, compact maize “Denghai 605” and shade-tolerant soybean “Nandou 25” were selected as cultivated materials. DA-6 with four concentrations, i.e., 0 mg/L (CK), 40 mg/L (D40), 60 mg/L (D60), and 80 mg/L (D80), were sprayed on soybean leaves at the beginning of flowering stage of soybean. Results showed that DA-6 treatments significantly (p < 0.05) increased soybean grain yield, and the yield increase ratio was higher in IS than SS. The leaf area index values and net photosynthesis rate of IS peaked at D60 and were increased by 32.2–49.3% and 24.1–27.2% compared with the corresponding CK. Similarly, DA-6 treatments increased the aboveground dry matter and the amount of soybean dry matter accumulation from the R1 stage to the R8 stage (VDMT) and highest at D60 both in IS and SS. D60 increased the VDMT by 29.0–47.1% in IS and 20.7–29.2% in SS. The TRG at D60 ranged 72.4–77.6% in IS and 61.4–62.5% in SS. The MDA content at D60 treatment was decreased by 38.3% in IS and 25.8% in SS. The active grain-filling day in IS was about 7 days longer than in SS. In D60 treatment, the Vmean and Vmax increased by 6.5% and 6.5% in IS and 5.7% and 4.3% in SS compared with the corresponding CK. Although the pod number and hundred-grain weight were significantly (p < 0.05) increased by DA-6 treatments, the grains per pod were maintained stable. The pod number and hundred-grain weight were increased by 30.1–36.8% and 4.5–6.7% in IS and 6.3–13% and 3.6–5.6% in SS. Thus, the grain yield at D60 was increased by 36.7–38.4% in IS and 21.7–26.6% in SS. DA-6 treatments significantly (p < 0.05) increased soybean grain yield and peaked D60 treatments both in IS and SS.

Rendimiento de la planta de frijol caupí [Vigna unguiculata (L.) Walp] y calidad nutricional en los sistemas de cultivo intercalado de frijol caupí y sorgo

In traditional row and strip cowpea-sorghum intercropping systems, cowpea forage yield reduces significantly due to intense competition and dominance of sorghum in acquiring growth resources. This field study evaluated novel mixed strip intercropping systems of forage cowpea and sorghum having different number of crops rows arranged under different spatial arrangements. Cowpea was intercropped with sorghum in 8, 12 and 16 rows strips with row-row spacing of 30, 45 and 60 cm. In each strip, equal number of rows of cowpea and sorghum were maintained. Factorial arrangement of randomized complete block design with three replicates was used to execute the field trials during summer seasons of 2013 and 2014. Strips having 12 rows and 60 cm row-row spacing positively affected all agronomic variables of cowpea which led to maximum forage yield (22.2 and 23.7 t ha-1 during 2013 and 2014 respectively) and dry matter biomass (6.63 and 6.94 t ha-1 during 2013 and 2014 respectively). In contrast, 8-rows strips having line spacing of 30 cm outperformed other intercropping systems by yielding the maximum herbage yield and dry matter biomass of sorghum. The intercropping system comprising of 12-rows strips with 60 cm row-row spacing remained superior in recording the maximum crude protein, fats and total ash along with the minimum fiber content of cowpea. In addition, this intercropping system under rest of spatial arrangements also remained unmatched, while 16-rows strips under all planting geometries remained inferior to other intercropping systems. Thus, cowpea intercropping with sorghum in 12-rows strips having 60 cm spacing offers biologically viable solution to improve biomass and forage quality of cowpea in intercropping with sorghum.

Productivity of Phosphorus Fertilization in Cowpea-Maize Strip Intercropping under Rainfed Conditions

Crop yields are declined due to low soil fertility, insufficient soil water availability and poorly managed cropping systems in Limpopo province of South Africa. Phosphorus (P) is a major essential nutrient element required by crops for enhanced growth and development. Interactions between different rates of P fertilization and strip intercropping system have not been studied in detail under rainfed conditions in semi-arid region of Limpopo province. Therefore, this study was conducted to assess the performance of four cowpea varieties at four levels (0, 15, 30, 45 kg P ha-1) of P fertilization in a cowpea-maize intercropping system in a split-split plot design during two seasons. Significant interactions were obtained between variety and phosphorus application as well as variety and cropping system for 90% physiological maturity, root mass and grain yield in both seasons. P levels significantly influenced and enhanced grain yield, land equivalent ratio, profit and benefit cost ratio achieved. PAN311 and TVu13464 matured earlier across P levels and they were selected promising cowpea varieties based on their early maturity and high yield. Land equivalent ratio values were greater than 1.0, which indicated performance and advantage of an intercropping system over monocropping system in land utilisation. The optimum P level for cowpea-maize strip intercropping was at 30 kg P ha-1 based on yield and financial return. The results showed that P application enhanced the productivity of the cowpea varieties in cowpea-maize strip intercropping in the semi-arid environment of Limpopo province. © 2021 Friends Science Publishers

Soil Nitrate Nitrogen Content and Grain Yields of Organically Grown Cereals as Affected by a Strip Tillage and Forage Legume Intercropping

Reducing tillage intensity and increasing crop diversity by including perennial legumes is an agrotechnical practice that strongly affects the soil environment. Strip tillage may be beneficial in the forage legume–cereals intercropping system due to more efficient utilization of biological nitrogen. Field experiments were conducted on a clay loam Cambisol to determine the effect of forage legume–winter wheat strip tillage intercropping on soil nitrate nitrogen (N-NO3) content and cereal productivity in various sequences of rotation in organic production systems. Forage legumes (Medicago lupulina L., Trifolium repens L., T. alexandrinum L.) grown in pure and forage legume–winter wheat (Triticum aestivum L.) strip tillage intercrops were studied. Conventional deep inversion tillage was compared to strip tillage. Nitrogen supply to winter wheat was assessed by the change in soil nitrate nitrogen content (N-NO3) and total N accumulation in yield (grain and straw). Conventional tillage was found to significantly increase N-NO3 content while cultivating winter wheat after forage legumes in late autumn (0–30 cm layer), after growth resumption in spring (30–60 cm), and in autumn after harvesting (30–60 cm). Soil N-NO3 content did not differ significantly between winter wheat strip sown in perennial legumes or oat stubble. Winter wheat grain yields increased with increasing N-NO3 content in soil. The grain yield was not significantly different when comparing winter wheat–forage legume strip intercropping (without mulching) to strip sowing in oat stubble. In forage legume–winter wheat strip intercropping, N release from legumes was weak and did not meet wheat nitrogen requirements.