Cauliflower Plant Organ Water Status and Nitrogen Translocation From Leaf–Stem Sources to Head Sinks in Its Three Hybrid Cultivars

Abstract

Cauliflower's (Brassica oleracea var. botrytis L.) fresh appearance and high nutritional values may be related to plant organ water holding and nitrogen (N) translocation from leaf-stem sources to head sinks. Cauliflower plant water and N nutrition relations were examined in a two-site field study in Nova Scotia. The objectives of this study were to assess cauliflower plant organ water and N translocation efficiency and to quantify the correlations between cauliflower plant organ water status, N translocation, head size, and fresh yield under various N treatments applied at shoot-tip-straightened stage. The experimental treatments consisted of three cauliflower hybrid cultivars (cvs. Minuteman, Sevilla, and Whistler) and three N combinations (105 + 30 + 0, 105 + 30 + 45, and 105 + 30 + 90 kg·ha −1 ) supplied at transplanting, seedling standing, and shoot straightened stage, respectively. The N treatments were arranged with four replicates in a split-block design in the two fields. Results showed that cauliflower plant N temporal storage in leaves and stems (source N) peaked (10.6 g/plant) at curd initiation. Plant water index was positively correlated with solar irradiance but negatively correlated with normalized difference vegetative index (NDVI). Nitrogen translocation from leaves and stems to heads was only 5% of total N uptake within the first week of the heading process, but the sink N reached 22.3%-24.9% (or 2.28-2.81 g/plant) of whole plant total N uptake within 15 days at head maturity. Mean N concentrations were significantly higher in heads (5.66%) than in leaves and stems (4.97%) at harvest (P < 0.05). The sink/source N ratios varied between 0.29

Variation in the Accumulation of Phytochemicals and Their Bioactive Properties among the Aerial Parts of Cauliflower

“…At harvest, the nitrogen concentration is higher in florets than leaf-stem. In our study, the highest protein content was observed in florets, but the difference between florets and leaf-stem was not as big as suggested by Hong [40]. However, the decrease in nitrogen was reported with the increase of the organ size [39,40].…”

“…In our study, the highest protein content was observed in florets, but the difference between florets and leaf-stem was not as big as suggested by Hong [40]. However, the decrease in nitrogen was reported with the increase of the organ size [39,40]. Thus, the lower protein concentration in florets can be related to its dilution in the vegetable tissue at the harvest stage.…”

“…In our study, the highest content of protein and the lowest content of GLS was noted in florets, confirming this theory. Hong [40] reported that the nitrogen storage is the highest in the leaf-stem at the curd initiation, and then the translocation of water and nitrogen to the floret is observed. At harvest, the nitrogen concentration is higher in florets than leaf-stem.…”

Thiamin stimulates growth, yield quality and key biochemical processes of cauliflower (Brassica oleracea L. var. Botrytis) under arid conditions

“…Like in cauliflower leaves, the head also contains significant amounts of phytochemicals and antioxidants [ 64 ]. However, the fresh appearance of cauliflower’s head and its reasonably promising nutrition levels have been reported to be attributable to plant part water holding capacity and translocation of essential mineral elements including primarily N [ 65 , 66 ]. In fact, N plays a vital role in the synthesis of a variety of amino acids, vitamins and proteins and thus it determines the yield and quality of the cauliflower crop [ 65 , 67 , 68 ].…”

“…However, the fresh appearance of cauliflower’s head and its reasonably promising nutrition levels have been reported to be attributable to plant part water holding capacity and translocation of essential mineral elements including primarily N [ 65 , 66 ]. In fact, N plays a vital role in the synthesis of a variety of amino acids, vitamins and proteins and thus it determines the yield and quality of the cauliflower crop [ 65 , 67 , 68 ]. Like several other inorganic nutrients, an optimal N translocation from the shoot (source) to the head (sink) is believed to determine nutritional quality of cauliflower [ 65 , 68 , 69 ].…”