Sugarcane (Saccharum spp. hybrid) successive planting (also called monoculture) causes serious yield losses and its management is not well studied in Histosols. Based on very few studies in other sugarcane regions, root colonization by harmful soil fungi is considered as a major cause of this yield decline, but there is lack of knowledge on its management in Histosols. A two-year greenhouse study was conducted with soil-drench application of mancozeb, mefenoxam, and azoxystrobin fungicides to determine their effects on early root and shoot growth, soil microbial communities, and nutrient uptake by plants. The study indicated that mancozeb soil application improved sugarcane-shoot and -root dry matter by 3–4 times and shoot-root length, fine-root length, and root surface area by 2–3 times compared to untreated soil. Phospholipid fatty acid (PLFA) analyses of sugarcane rhizosphere soil showed significant reduction in fungal-biomarker abundance with mancozeb and azoxystrobin in comparison to the untreated check or mefenoxam treatments. Bacterial functional-group abundance was reduced by mancozeb and mefenoxam. All fungicides significantly reduced mycorrhizal colonization but not mycorrhizal spore counts. There was a functional relationship between fine-root systems and higher tissue concentration of nitrogen and silicon. The study indicated that application of fungicides to the soil may improve early root and shoot growth and plant-cane establishment that can potentially reduce the yield decline in successively planted sugarcane in histosols. Additional field research is needed in the future to determine the fungicide soil application method, sugarcane growth response in whole crop cycles, and any environmental effects.

Leaf surface area (A) and leaf shape have been demonstrated to be closely correlated with photosynthetic rates. The scaling relationship between leaf biomass (both dry weight and fresh weight) and A has been widely studied. However, few studies have focused on the scaling relationship between leaf shape and A. Here, using more than 3600 leaves from 12 Rosaceae species, we examined the relationships of the leaf-shape indices including the left to right side leaf surface area ratio (AR), the ratio of leaf perimeter to leaf surface area (RPA), and the ratio of leaf width to length (RWL) versus A. We also tested whether there is a scaling relationship between leaf dry weight and A, and between PRA and A. There was no significant correlation between AR and A for each of the 12 species. Leaf area was also found to be independent of RWL because leaf width remained proportional to leaf length across the 12 species. However, there was a negative correlation between RPA and A. The scaling relationship between RPA and A held for each species, and the estimated scaling exponent of RPA versus A approached −1/2; the scaling relationship between leaf dry weight and A also held for each species, and 11 out of the 12 estimated scaling exponents of leaf dry weight versus A were greater than unity. Our results indicated that leaf surface area has a strong scaling relationship with leaf perimeter and also with leaf dry weight but has no relationship with leaf symmetry or RWL. Additionally, our results showed that leaf dry weight per unit area, which is usually associated with the photosynthetic capacity of plants, increases with an increasing A because the scaling exponent of leaf dry weight versus A is greater than unity. This suggests that a large leaf surface area requires more dry mass input to support the physical structure of the leaf.

Proper sowing orientation and spacing are important factors for best crop growth. A field experiment was conducted to study the effect of different planting patterns with and without lentil intercropping on sugarcane growth and yield and farm economics. Each of these treatments were planted as sole crop and intercropped with lentil. Data were collected on plant cane and first ratoon crop. The maximum stripped cane yields (154.36 t/ha and 130.28 t/ha in plant and ratoon crop, respectively) were obtained from sugarcane planted at 120 cm trench planting both as sole as well as lentil intercropped. This treatment also attained 61% and 43% higher total sugar yields compared to traditional 60 cm single rows planting in plant and ratoon crops, respectively. Lentil intercropping did not have any significant effect on sugarcane yield, but trench planting at 120 cm with lentil intercropping had the highest lentil seed yield (598.0 in 2013–2014 and 629.8 kg ha⁻¹ in 2014–2015) along with maximum land equivalent ratio (1.40 and 1.37), net return (Rs.321254/ha), net field benefit (Rs.491703/ha) and benefit cost ratio (2.01). Sugarcane at 120 cm trench planting with lentil intercropping also outperformed other planting patterns in improving economic returns.

The lesser cornstalk borer, Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) is an important pest of sugarcane (a complex hybrid of Saccharum spp.) in southern Florida. Reproductive and life table parameters for E. lignosellus were examined at nine constant temperatures from 13 to 36 °C with sugarcane as the larval food source. The pre- and post-oviposition periods decreased with increasing temperatures and reached their minimums at 33 and 36 °C, respectively. The oviposition period was longest at 27 °C. The mean fecundity, intrinsic rate of increase (r), and finite rate of increase (λ) were greatest at 30 °C and decreased with increasing or decreasing temperature. The net reproductive rate (R₀) was greatest at 27 °C. The Brière-1 model best described the relationship between temperature and r. The generation (T) and population doubling times (DT) were shortest at 33 and 30 °C, respectively. The temperatures around 27 to 30 °C are most favorable for E. lignosellus population growth and significant damage can be expected under these climatic conditions. This data in combination with population monitoring of E. lignosellus under field conditions can be effectively used in population predictions of this pest in field and severe damage can be prevented by timely implementation of control measures. El barrenador menor del tallo de maíz Elasmopalpus lignosellus (Zeller) (Lepidoptera: Pyralidae) es una plaga importante de la caña de azúcar (un híbrido complejo de Saccharum spp.) en el sur de la Florida. Se examinaron los parámetros reproductivos y la tabla de vida para E. lignosellus en nueve temperaturas constantes de 13 a 36 °C, con caña de azúcar como fuente de alimento para las larvas. Los períodos del pre-y de pos-oviposición disminuyeron con el aumento de las temperaturas y alcanzó sus mínimos en 33 y 36 °C, respectivamente. El período de oviposición más largo fue a 27 °C. El promedio de la fecundidad, la tasa intrínseca de crecimiento (r) y la tasa finita de crecimiento (λ) fueron mayores a 30 °C y disminuyeron con el aumento o disminución de la temperatura. La tasa neta de reproducción (R₀) fue mayor a 27 °C. El modelo Brière-1 describe mejor la relación entre la temperatura y r. El tiempo de generación (T) y de duplicación de la población (DT) fueron más cortos a los 33 y 30 °C, respectivamente. Las temperaturas alrededor de 27 a 30 °C son las más favorables para el crecimiento de la población de E. lignosellus y se puede esperar daño significativo bajo estas condiciones climáticas. Estos datos, en combinación con el monitoreo de la población de E. lignosellus, en condiciones de campo puede ser utilizado eficazmente en la predicción de la población de esta plaga y se puede prevenir daño severo por la aplicación puntual de medidas de control.

Sugarcane yields are declining under successive planting (monoculture) compared to other planting systems in Florida Histosols. To evaluate soil properties related to the sugarcane yield decline, an on-farm study was conducted on soil chemical, biological, and microbial indicators variation with soil samples collected from successive green cane or burnt cane harvest, flooded fallow, and rice and sweetcorn rotation planting sites. Overall, harvest residue incorporated in the soil in green cane harvest and corn rotation increased organic matter, total carbon and C:N ratios which resulted in higher microbial biomass parameters and total PLFA biomass. However, successive planting with burnt cane harvest reduced total soil carbon and hence microbial biomass. Findings suggested that these parameters should be considered for further research to determine specific causes of sugarcane yield decline in successive planting.