Stewart Reed

Plastic Mulches and Row Covers on Growth and Production of Summer Squash

ABSTRACT Row covers and colored plastic mulch are used routinely throughout the United States to grow vegetables but are rarely used in conjunction to produce a crop. Summer squash (Cucurbita pepo L.), cv. Prelude II, was grown on an Orangeburg sandy loam soil in Shorter, AL. The summer squash was direct seeded in single rows. The experiment consisted of 12 treatments including: (1) black plastic mulch (BPM)+spunbonded row cover (RC), (2) BPM alone, (3) white plastic mulch (WPM)+RC, (4) WPM alone, (5) red plastic mulch (RPM)+RC, (6) RPM alone, (7) bare soil (BS)+RC, (8) BS alone, (9) silver plastic mulch (SPM)+RC, (10) SPM alone, (11) blue plastic mulch (BLUPM)+RC, and (12) BLUPM alone. Year and mulch color affected all variables, row cover affected plant height and stem diameter, and the mulch color × row cover interaction affected yield variables. Mulch color and year significantly affected air and soil temperatures and row cover significantly affected air temperature. Soil temperatures were more than 5°C lower than air temperatures in all treatments and air temperatures were 2–5°C higher with row covers than without. Increased soil and air temperatures did not always result in yield increases. Colored plastic mulch with or without row covers did not increase early fruit yield in squash. Lack of a mulch/row cover induced temperature effect on yield was attributed to the relatively high mean air temperatures that may have masked treatment temperature effects.

Nitrogen Fertilization Effects on Recovery of Bush Beans from Flooding

ABSTRACT Nitrogen loss can be a serious problem to vegetable growers in flood-prone areas. In south Florida, waterlogged soil can cause plant N stress through nitrate leaching, denitrification, and reduced N uptake and assimilation. The Comprehensive Everglades Restoration Project will increase water flow into Everglades National Park, resulting in frequent flooding on adjacent agricultural lands. A greenhouse study was conducted to determine effects of nitrogen application method on recovery from flood damage in bush beans (Phaseolus vulgaris L.). There were three fertilizer treatments: 1) normal: ½ N applied preplant, ½ applied at flowering; 2) liquid: daily liquid applications with irrigation water; and 3) foliar: normal fertility treatment plus two foliar spray treatments applied after flooding. Plants were flooded to 1 cm above the soil surface for 2 or 4 days, drained, and allowed to continue to grow under normal greenhouse conditions. At harvest, plants receiving the liquid treatment had a greater pod fresh weight (FW) than those receiving normal and foliar fertility treatments. From planting through recovery from flooding (day 45), the liquid fertility treatment tended to maintain chlorophyll levels either equal to or greater than those of the foliar and normal treatments. Plants receiving liquid fertilizer tended to have a net photosynthetic rate higher than the other fertility methods and recovered faster, and to higher photosynthetic levels, after flooding. Plants flooded for 2 days and receiving the liquid treatment appeared to have a denser root system and a larger leaf area than the other treatment. These plants probably resisted flood damage longer and were better able to recover from injury, and this likely resulted in higher pod FW than the other treatments. Daily liquid fertility treatments (fertigation) may be an acceptable strategy to mitigate certain effects of flood damage to beans.

Flooding Influences on Growth and Development of Bush Bean Under Greenhouse Conditions

Abstract Crop production in humid climates is often limited by severe thunderstorms that may leave soil flooded or waterlogged for several days. In 2001, a greenhouse study was initiated to determine the tolerance of bush beans (Phaseolus vulgaris L.) to flooding of various durations and at different growth stages. Plants were subjected to eleven flooding treatments lasting from one to eleven days. Flood treatments were initiated when plants reached either early vegetative growth stage (second true leaf open), early reproductive stage (first flower open on the main stem) or late reproductive stage (green seeds fills 1/2 of the pod cavity). In Study 1 flooding during the early vegetative growth stage for one, two and five days resulted in both the number of pods produced and pod fresh weight being statistically similar to that of the non-flooded control. The remaining flood treatments resulted in pod fresh weights 73% or less than the control weight. The number of surviving plants had more influence on the pod fresh weight than did flood duration. The number of pods produced per plant was correlated to pod fresh weight (r2 = 0.90). Only one plant grown to either the early or late reproductive growth stage survived flooding for >24 h. There was a 21% yield reduction for plants flooded for 24 h during the early reproductive growth stage. Flooding for 24 h at the late reproductive stage resulted in a 50% yield reduction. In Study 2 plants flooded during early vegetative growth stage did not flower. Flooding during the late vegetative and flowering growth stages caused a 70% and 49% reduction in yield, respectively. Pod production slowed with increasing flood duration. Yield could be correlated to several plant physical characteristics. We found linear relationships between yield components (pod number and weight) and flood duration, flood timing and leaf area. Greenhouse data indicate that yield reduction can be estimated from changes in plant characteristics resulting from flooding.

Evaluation Of Composted Insect Rearing Waste As A Potting Substrate For Radish, Squash And Green Bean

A study was initiated to determine the potential for composted solid and semi-solid insect rearing waste as a growth substrate for plants. The substrate consisted of fruit fly colony waste (CW) prepared by washing an agar-based larval diet through a vermiculite pupation substrate, which was then composted for six weeks prior to use. Radish (Raphanus sativus L.) was grown in either a commercial potting mixture or blends of colony waste (CW) and equal parts compost plus peat (CP). Squash (Cucurbita pepo L.) was grown in different ratios of CW:sand (S) mixtures. Mixes of 80:20 and 100:0 CW:CP had radish germination rates equal to the commercial mix. Radish shoot dry weights from 80, 60 and 40% CW were higher than those from the commercial mix. Squash grown in 20% CW had the highest shoot and root dry weights. No substance in the CW appeared to be detrimental to plant growth. Composted insect rearing waste is a material rich in nutrients and suitable for inclusion in a potting mixture. A mixture of peat and 30-70% CW resulted in plant performance greater than or equal to that observed with a commercial mix.

Phosphorus leaching potential from compost amendments in a carbonatic soil

Composts are applied to carbonatic soils in south Florida to improve their physical characteristics and increase water retention. Blends of biosolids and municipal waste are often combined to increase the nutrient content of the compost. However, the high P content of some compost has led to concerns about the potential for P movement into shallow groundwater. Studies were conducted to determine the potential for P leaching in soil amended with biosolids, clean organic waste, and Bedminster composts. Bedminster was the most suitable of the composts used in terms of a lower potential for P leaching as a result of P sorption in the amended soil. Each compost-amended soil demonstrated a slight decrease in P leaching at 1 pore volume after simulated rainfall (21 cm). Pore volume was defined as the total volume in a column less the volume of solids. The high P content of the composts made it unlikely that additions of these materials to soil would improve P sorption capacity. However, Bedminster and clean organic waste did not significantly increase P leaching above that of the soil. Caution should be exercised when applying these composts because materials themselves contain an enormous amount of P that could be eventually transported into the groundwater.