Root Development of Bell Pepper (Capsicum annuum L.) as Affected by Water Salinity and Sink Strength.

Fruits are the dominant sinks for assimilates. At optimal conditions, assimilates supply can meet the demand of fruits and those of the vegetative organs; however, extreme circumstances such as strong sink strength or an environmental stress may disturb this fine balance. While most studies focus on aboveground parameters, information regarding root growth dynamics under variable sink strength are scarce. The objective of this study was to evaluate the effect of sink strength (represented by fruit load) and salinity on bell-pepper root development. Three levels of fruit load were combined with two salinity levels in plants grown in an aeroponic system. Root growth was determined both by root capacitance and destructive measurements. Salinity and sink strength significantly affected root, shoot and fruit growth dynamics. Root growth was less affected by fruit load. Salinity stress was negatively associated with shoot growth, but after an acclimation period, salinity enhanced root development. Additionally, this study shows for the first time that root capacitance is a valid approach for non-destructive measurement of root development in aeroponic systems. The good correlation measured by us (r2 0.86) opens new opportunities for continuous root growth monitoring in aeroponic systems in the future.

Biochar potential in intensive cultivation of Capsicum annuum L. (sweet pepper): crop yield and plant protection.

BACKGROUND: The influence of various biochars on crop yield and disease resistance of Capsicum annuum L. (sweet pepper) under modern, high input, intensive net house cultivation was tested over the course of 2011-2014 in the Arava desert region of Israel. A pot experiment with Lactuca sativa L. (lettuce) grown in the absence of fertilizer employed the 3-year-old field trial soils to determine if biochar treatments contributed to soil intrinsic fertility. RESULTS: Biochar amendments resulted in a significant increase in the number and weight of pepper fruits over 3 years. Concomitant with the increased yield, biochar significantly decreased the severity of powdery mildew (Leveillula taurica) disease and broad mite (Polyphagotarsonemus latus) pest infestation. Biochar additions resulted in increased soil organic matter but did not influence the pH, electrical conductivity or soil or plant mineral nutrients. Intrinsic fertility experiments with lettuce showed that two of the four biochar-treated field soils had significant positive impacts on lettuce fresh weight and total chlorophyll, carotenoid and anthocyanin contents. CONCLUSION: Biochar-based soil management can enhance the functioning of intensive, commercial, net house production of peppers under the tested conditions, resulting in increased crop yield and plant resistance to disease over several years. © 2017 Society of Chemical Industry.

Pepper Rootstock Graft Compatibility and Response to Meloidogyne javanica and M. incognita.

Resistance of pepper species (Capsicum annuum, C. baccatum, C. chinense, C. chacoense, and C. frutescens), cultivars and accessions to the root-knot nematodes Meloidogyne incognita race 2 and M. javanica, and their graft compatibility with commercial pepper varieties as rootstocks were evaluated in growth chamber and greenhouse experiments. Most of the plants tested were highly resistant to M. javanica but susceptible to M. incognita. Capsicum annuum AR-96023 and C. frutescens accessions as rootstocks showed moderate and relatively high resistance to M. incognita, respectively. In M. incognita-infested soil in a greenhouse, AR-96023 supported approximately 6-fold less nematode eggs per gram root and produced about 2-fold greater yield compared to a nongrafted commercial variety. The commercial variety grafted on AR-96023 produced a yield as great as the non-grafted variety in the root-knot nematode-free greenhouse. Some resistant varieties and accessions used as rootstocks produced lower yields (P < 0.01) than that of the non-grafted variety in the noninfested greenhouse. Use of rootstocks with nematode-resistance and graft compatibility may be effective for control of root-knot nematodes on susceptible pepper.