The objective of the present work was to determine the relationship between spectral reflectance indices (SRI) and yield in spring wheat (Triticum aestivum L.) in NW Mexico in three environments (irrigated, water‐stress, and high‐temperature). The SRI were classified into vegetative indices (three indices) and water indices (five indices). The SRI were determined at booting, heading, and grain‐filling in advanced lines of three trials of the International Maize and Wheat Improvement Centre in Mexico (CIMMYT), Elite Spring Wheat Yield Trial (ESWYT), Semi‐Arid Wheat Yield Trial (SAWYT), and High Temperature Wheat Yield Trial (HTWYT). Two water indices (NWI‐1 and NWI‐3) always provided higher correlations with grain yield when heading and grain filling were combined in SAWYT, ESWYT, and HTWYT. Vegetative indices showed inconsistency in their relationship with grain yield. The water indices gave higher genetic correlations and correlated response with grain yield than the vegetative indices in the three trials in all the environments across years. The relationship between yield and canopy temperature determined at grain filling also showed stronger association with yield. The high‐temperature environment showed the strongest associations between SRI and grain yield. The water indices can be used for breeding purposes for selecting high‐yielding lines in well‐irrigated, water‐stressed, and hot environments, and canopy temperature could complement this selection.

Spectral reflectance indices can be used to estimate the water status of plants in a rapid, non-destructive manner. Water spectral indices were measured on wheat under a range of water-deficit conditions in field-based yield trials to establish their relationship with water relations parameters as well as available volumetric soil water (AVSW) to indicate soil water extraction patterns. Three types of wheat germplasm were studied which showed a range of drought adaptation; near-isomorphic sister lines from an elite/elite cross, advanced breeding lines, and lines derived from interspecific hybridization with wild relatives (synthetic derivative lines). Five water spectral indices (one water index and four normalized water indices) based on near infrared wavelengths were determined under field conditions between the booting and grain-filling stages of crop development. Among all water spectral indices, one in particular, which was denominated as NWI-3, showed the most consistent associations with water relations parameters and demonstrated the strongest associations in all three germplasm sets. NWI-3 showed a strong linear relationship (r2 >0.6–0.8) with leaf water potential (ψleaf) across a broad range of values (–2.0 to –4.0 MPa) that were determined by natural variation in the environment associated with intra- and inter-seasonal affects. Association observed between NWI-3 and canopy temperature (CT) was consistent with the idea that genotypes with a better hydration status have a larger water flux (increased stomatal conductance) during the day. NWI-3 was also related to soil water potential (ψsoil) and AVSW, indicating that drought-adapted lines could extract more water from deeper soil profiles to maintain favourable water relations. NWI-3 was sufficiently sensitive to detect genotypic differences (indicated by phenotypic and genetic correlations) in water status at the canopy and soil levels indicating its potential application in precision phenotyping.

Paprika pepper (Capsicum annuum var. annuum L., `Agridulce SIA') was direct-seeded on raised beds in double rows 0.35 cm apart. Plants were thinned within the row to establish densities ranging from 13,333 to >500,000 plants/ha. Yield of paprika pepper increased as plant density increased, but plant densities >200,000 plants/ha resulted in only small increases in yield. Fruit number and dry fruit weight/plant decreased with increasing plant populations, and weight/fruit decreased slightly. The increase in yield/ha as plant density increased was a result of increased numbers of fruits/ha. Pigment content (ASTA units) declined linearly as plant density increased, whereas moisture content of red fruits at harvest remained unaffected. Plant densities in the range of 150,000 to 200,000 plants/ha were optimal in terms of fruit yield and pigment content.

Canopy reflectanoe plays an inoreasingly important role in orop management and yield prediction at large soale. The relationship of four speotrai refieotance indices with cotton {Gos-sypium hirsutum L.) biomass, leaf area index (LAI), and crop yield were investigated using three cotton varieties and five N rates in the irrigated low desert in Arizona during the 2009 and 2010 growing seasons. Biomass, LAI, and canopy reflectance indices (normalized difference vegetation index [NDVI], simple ratio [SR], near-infrared index [NIR], and ratio vegetation index [RVI]) were determined at different growth stages. The commonly used NDVI and the other three canopy reflectance indices explained over 87% variation in cotton biomass (all R^ > 0.87) and LAI {R^ > 0.93). Indices SR, NIR, and RVI ail had higher coefficients of determination {R^) compared to NDVI because these indices were not saturated at late growth stages. There was no significant relationship between lint yield and the spectral indices measured at eariy growth stages. However, the spectral indices determined at peak bloom showed significant correlations with lint yield. Indices SR, NiR, and RVI explained 56, 60, and 58% of variations in cotton lint yield, respectively, while NDVI only explained 47% of variation in lint yield. This study suggests canopy reflectance indices can be used to predict cotton lint yield at peak bloom and the accuracy of yield prediction can be significantly improved when SR, NIR, and RVI are used.

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Cotton response to fruiting branch removal (FBR) is critical information in estimating plant recovery potential and making management decisions after hail storms or other physical damages. Fruiting branches were removed at first bloom (R8), 2.5‐cm boll (R12) and peak bloom (R16) growth stages. Five FBR treatments were conducted at each of the above three growth stages: 0 %, 25 %, 50 %, 75 % and 100 %. At harvest, five plants were randomly chosen from each plot and branches separated into three groups: vegetative, lower and upper fruiting branches. Lower fruiting branches were from the nodes where FBR treatments were conducted, whereas upper fruiting branches were the new branches developed after FBR. Seed cotton weight, open boll number and node number in each group were recorded. Fruiting branch removal increased boll number, boll size and boll/node on the upper fruiting branches, which compensated yield loss on lower fruiting branches. Generally, FBR at the first bloom reduced cotton yield more than it did at the 2.5‐cm boll and peak bloom growth stages when FBR percentage was lower than 75 %. The removal of all 16 fruiting branches at peak bloom reduced cotton yield by 16.8 %, indicating remarkable compensation ability by cotton plants in climates with a long growing season.

Aqueous solutions of low concentrations of salicylic acid (SA), applied as a spray to the shoots of 3-month-oldPinus patula Schiede ex Schltdl. & Cham seedlings, significantly increased the biomass of the plants. The measurements were taken after nine monthly treatments. Stem diameter and height of the plants were increased by 10-10 and 10-8 M SA. Similarly, applications of 10-8 and 10-6 M SA increased fresh stem weight by 33 and 30%, respectively, and the dry stem weight by 65 and 44%. Increases of 28–30% in gross root length were detected in applications of 10-8 and 10-6 M SA, which were reinforced by increases of 33% in fresh root weight, and of 45 to 54% in dry root weight. South. J. Appl. For. 27(1):52–54.